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; Copyright 1996 Acorn Computers Ltd
;
; Licensed under the Apache License, Version 2.0 (the "License");
; you may not use this file except in compliance with the License.
; You may obtain a copy of the License at
;
;     http://www.apache.org/licenses/LICENSE-2.0
;
; Unless required by applicable law or agreed to in writing, software
; distributed under the License is distributed on an "AS IS" BASIS,
; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
; See the License for the specific language governing permissions and
; limitations under the License.
;
        TTL   => ChangeDyn

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        ; OS_ChangeDynamicArea optimisations:

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        GBLL  FastCDA_Bulk ; Do all cache/TLB maintenance in bulk instead of on a per-page basis
FastCDA_Bulk SETL {TRUE}
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        GBLL  FastCDA_FIQs ; Don't thrash ClaimFIQ/ReleaseFIQ in DoTheGrowPagesSpecified
FastCDA_FIQs SETL {TRUE}

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        GBLL  FastCDA_Unnecessary ; Avoid unnecessary cache cleaning in DoTheGrowPagesSpecified
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FastCDA_Unnecessary SETL {TRUE}

        ; DoTheGrowPagesSpecified profiling code
        ; Written to use Cortex-A8 cycle count performance counter - will need modifying for other CPUs!

        GBLL  FastCDA_Prof
FastCDA_Prof SETL {FALSE}

      [ FastCDA_Prof
        ; Squeeze profiling workspace into "free space after envstring"
                                 ^ ExtendedROMFooter+4
        ! 0, "FastCDA_Prof workspace at ":CC::STR:@
FastCDA_Prof_DoTheGrowInit           # 4
FastCDA_Prof_MarkRequired            # 4
FastCDA_Prof_PagesUnsafe             # 4
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FastCDA_Prof_DoublyRemoveCacheability # 4
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FastCDA_Prof_DoublyMovePages         # 4
FastCDA_Prof_FindSpare               # 4
FastCDA_Prof_ClaimFIQ                # 4
FastCDA_Prof_AccessPhysical          # 4
FastCDA_Prof_CopyPage                # 4
FastCDA_Prof_ReleasePhysical         # 4
FastCDA_Prof_MoveReplacement         # 4
FastCDA_Prof_MoveNeeded              # 4
FastCDA_Prof_ReleaseFIQ              # 4
FastCDA_Prof_PagesSafe               # 4
FastCDA_Prof_CallPreGrow             # 4
FastCDA_Prof_CallPostGrow            # 4
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FastCDA_Prof_MMUChangingCached       # 4 ; MMU_ChangingUncached followed by Cache_CleanInvalidateaAll
FastCDA_Prof_MMUChangingUncached     # 4 ; MMU_ChangingUncached followed by nothing
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FastCDA_Prof_ChangingEntry           # 4
        ASSERT @ <= &500
      ]

        MACRO
        FastCDA_ProfInit $temp
      [ FastCDA_Prof
        MVN     $temp,#0
        MCR     p15,0,$temp,c9,c12,2
        MOV     $temp,#1<<31
        MCR     p15,0,$temp,c9,c12,1
        MOV     $temp,#7
        MCR     p15,0,$temp,c9,c12,0
      ]
        MEND

        MACRO
        FastCDA_ProfStart $var,$temp,$temp2,$temp3,$cc
      [ FastCDA_Prof
        LDR$cc  $temp,=ZeroPage+FastCDA_Prof_$var
        LDR$cc  $temp2,[$temp]
        MRC$cc  p15,0,$temp3,c9,c13,0
        SUB$cc  $temp2,$temp2,$temp3
        STR$cc  $temp2,[$temp]
      ]
        MEND

        MACRO
        FastCDA_ProfEnd $var,$temp,$temp2,$temp3,$cc
      [ FastCDA_Prof
        MRC$cc  p15,0,$temp3,c9,c13,0
        LDR$cc  $temp,=ZeroPage+FastCDA_Prof_$var
        LDR$cc  $temp2,[$temp]
        ADD$cc  $temp2,$temp2,$temp3
        STR$cc  $temp2,[$temp]
      ]
        MEND

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;******************************************************************************
; ChangeDynamic SWI
; In  : R0 =  0 => System Heap,
;             1 => RMA
;             2 => Screen
;             3 => Sprite area
;             4 => Font cache
;             5 => RAM disc
;             6 => Free pool
;       R1 = no of bytes to change by
;
; Out : V set if CAO in AplWork or couldn't move all the bytes requested.
;       R1 set to bytes moved.
;******************************************************************************

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; OS access privileges (OSAP_ to differentiate from AP_ used in Hdr:MEMM.*)
OSAP_Full * 0 ; user r/w/x, priv r/w/x
OSAP_Read * 1 ; user r/x, priv r/w/x
OSAP_None * 2 ; user none, priv r/w/x
OSAP_ROM  * 3 ; user r/x, priv r/x

; Corresponding values for OS_Memory 24
; (n.b. - XN flag is inverted)
CMA_ROM  * CMA_Partially_UserR+CMA_Partially_UserXN+CMA_Partially_PrivR+CMA_Partially_PrivXN
CMA_Read * CMA_ROM+CMA_Partially_PrivW
CMA_Full * CMA_Read+CMA_Partially_UserW
CMA_None * CMA_Partially_PrivR+CMA_Partially_PrivW+CMA_Partially_PrivXN

; Convenience macro for defining DA/page flags and corresponding CMA value
        MACRO
$area   DefAreaFlags $ap, $extra
AreaFlags_$area * OSAP_$ap :OR: ($extra + 0)
CMA_$area * CMA_$ap
        MEND

; Flags for kernel-managed DAs
AppSpace         DefAreaFlags Full
SysHeap          DefAreaFlags Full
RMA              DefAreaFlags Full
Screen           DefAreaFlags Full, DynAreaFlags_NotCacheable :OR: DynAreaFlags_DoublyMapped :OR: DynAreaFlags_NeedsSpecificPages
Sprites          DefAreaFlags Full
FontArea         DefAreaFlags None
RAMDisc          DefAreaFlags None, DynAreaFlags_NotCacheable
RAMDisc_SA       DefAreaFlags None ; StrongARM-specific (~CB gives poor performance for current StrongARMs)
FreePool         DefAreaFlags None, DynAreaFlags_NotCacheable :OR: DynAreaFlags_NotBufferable :OR: DynAreaFlags_PMP

; Flags for other kernel managed areas

Duff                 DefAreaFlags None, DynAreaFlags_NotCacheable :OR: DynAreaFlags_NotBufferable
CursorChunkCacheable DefAreaFlags Read, PageFlags_Unavailable ; Should be OSAP_None?
CursorChunk          DefAreaFlags Read, PageFlags_Unavailable :OR: DynAreaFlags_NotCacheable
L2PT                 DefAreaFlags None, DynAreaFlags_NotCacheable :OR: DynAreaFlags_NotBufferable
L1PT                 DefAreaFlags None, DynAreaFlags_NotCacheable :OR: DynAreaFlags_NotBufferable :OR: PageFlags_Unavailable
HALWorkspace         DefAreaFlags Read, PageFlags_Unavailable
HALWorkspaceNCNB     DefAreaFlags None, DynAreaFlags_NotCacheable :OR: DynAreaFlags_NotBufferable :OR: PageFlags_Unavailable
ZeroPage             DefAreaFlags Read, PageFlags_Unavailable
ScratchSpace         DefAreaFlags Read, PageFlags_Unavailable
DCacheClean          DefAreaFlags None ; ideally, svc read only, user none but hey ho
CAM                  DefAreaFlags None, PageFlags_Unavailable
SVCStack             DefAreaFlags Read, PageFlags_Unavailable
IRQStack             DefAreaFlags None, PageFlags_Unavailable
ABTStack             DefAreaFlags None, PageFlags_Unavailable
UNDStack             DefAreaFlags None, PageFlags_Unavailable
Kbuffs               DefAreaFlags Read, PageFlags_Unavailable
DebuggerSpace        DefAreaFlags Read, PageFlags_Unavailable
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  [ DA_Batman
ChangeDyn_Batcall    * -3               ; special DA number to select Batman usage of OS_ChangeDynamicArea
  ]
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ChangeDyn_FreeAndApl * -2               ; special reason code for when we're sucking out of free pool and apl space
ChangeDyn_AplSpace   * -1
ChangeDyn_SysHeap    * 0
ChangeDyn_RMA        * 1
ChangeDyn_Screen     * 2
ChangeDyn_SpriteArea * 3
ChangeDyn_FontArea   * 4
ChangeDyn_RamFS      * 5
ChangeDyn_FreePool   * 6
ChangeDyn_MaxArea    * 6

; Number of entries in page block on stack

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NumPageBlockEntries *   63
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PageBlockSize   *       NumPageBlockEntries * 12
PageBlockChunk  *       NumPageBlockEntries * 4096

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;
; mjs - performance enhancements (from Ursula, merged into HALised kernel June 2001)
; Workspace for acceleration of operations on a DA, by reducing need to traverse DA list.
;
; - accelerates allocating non-quick DA numbers to O(n) instead of laughable O(n*n), where n is no. of DAs
; - accelerates enumeration to O(n) instead of laughable O(n*n)
; - allocation of a quick handle (DA number) is O(1)
; - access of a DA node from a quick handle is O(1)
; - access of a DA node from a non-quick handle is O(1), if it repeats the most recent non-quick handle access (else O(n))
;
; - creation of a DA still has some O(n) work (requires search for address space), but is now rather quicker
; - removal of a DA is still O(n) (requires traversal of list in order to get previous node)
; - other uses of a DA with a quick handle (eg. get info, change size) avoid any O(n) work
;
; - all system handles will be quick.
; - non-system handles will be quick, except for very large numbers of DAs, or silly modules like the Wimp who insist on
;   their own silly DA number (the latter can still benefit from LastTreacleHandle - see below)
;
; Limitations:
; - does not allow anyone to choose their own DA number that clashes with the quick handle set - should not
;   be a problem since choosing own number reserved for Acorn use
; - does not allow anyone to renumber a DA with a quick handle - again, reserved for system use
; - DA names will be truncated to a maximum of 31 characters (or as defined below)
;
                                  GBLL DynArea_QuickHandles
DynArea_QuickHandles              SETL {TRUE}
;
      ;various bad things happen if DynArea_QuickHandles is FALSE (eg. some new API disappears)
      ;should remove FALSE build option to simplify source code next time kernel is updated (kept for reference/testing now)
      ASSERT DynArea_QuickHandles

                                  GBLL DynArea_NullNamePtrMeansHexString
DynArea_NullNamePtrMeansHexString SETL {TRUE} :LAND: DynArea_QuickHandles
;
  [ DynArea_QuickHandles
DynArea_MaxNameLength     * 31                      ;maximum length of DA name, excluding terminator (multiple of 4, -1)
DynArea_NumQHandles       * 256                     ;maximum no. of non-system quick handles available simultaneously
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DynArea_AddrLookupBits    * 8                       ;LUT covers entire 4G logical space, so 4G>>8 = 16M granularity
DynArea_AddrLookupSize    * 1<<(32-DynArea_AddrLookupBits) ; Address space covered by each entry
DynArea_AddrLookupMask    * &FFFFFFFF-(DynArea_AddrLookupSize-1)
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;
                          ^  0,R11
DynArea_TreacleGuess      # 4                       ;guess for next non-quick handle to allocate, if needed, is TreacleGuess+1
DynArea_CreatingHandle    # 4                       ;handle proposed but not yet committed, during DynArea_Create, or -1 if none
DynArea_CreatingPtr       # 4                       ;ptr to proposed DANode during DynArea_Create (invalid if CreatingHandle = -1)
DynArea_LastTreacleHandle # 4                       ;last non-quick handle accessed by a client (usually the Wimp), or -1 if none
DynArea_LastTreaclePtr    # 4                       ;ptr to DANode for last non-quick handle accessed (invalid if LastTreacleHandle = -1)
DynArea_LastEnumHandle    # 4                       ;last handle enumerated, or -1 if none
DynArea_LastEnumPtr       # 4                       ;ptr to DANode for last handle enumerated (invalid if LastEnumHandle = -1)
DynArea_ShrinkableSubList # 4                       ;sub list of dynamic areas that are Shrinkable (0 if none)
DynArea_OD6Signature      # 4                       ;signature of changes to non-system DAs since last call to OS_DynamicArea 6
                                                    ;bit  0 = 1 if any DAs have been created
                                                    ;bit  1 = 1 if any DAs have been removed
                                                    ;bit  2 = 1 if any DAs have been resized (excluding grow or shrink at creation or removal)
                                                    ;bit  3 = 1 if any DAs have been renumbered
                                                    ;bits 4-30   reserved (0)
                                                    ;bit 31 = 1 if next resize is not to update signature (used during create, remove)
DynArea_OD6PrevSignature  # 4                       ;previous signature, used to distinguish single from multiple changes
DynArea_OD6Handle         # 4                       ;handle of last DA that affected signature
DynArea_OD8Clamp1         # 4                       ;clamp value on area max size for OS_DynamicArea 0 with R5 = -1
                                                    ;(default -1, set by R1 of OS_DynamicArea 8)
DynArea_OD8Clamp2         # 4                       ;clamp value on area max size for OS_DynamicArea 0 with R5 > 0 (not Sparse)
                                                    ;(default -1, set by R2 of OS_DynamicArea 8)
DynArea_OD8Clamp3         # 4                       ;clamp value on area max size for OS_DynamicArea 0 for a Sparse area
                                                    ;(default 4G-4k, set by R3 of OS_DynamicArea 8)
DynArea_SortedList        # 4                       ;alphabetically sorted list of non-system areas, or 0 if none
DynArea_SysQHandleArray   # 4*(ChangeDyn_MaxArea+1) ;for system areas 0..MaxArea, word = ptr to DANode, or 0 if not created yet
DynArea_FreeQHandles      # 4                       ;index of first free quick handle, starting at 1 (or 0 for none)
DynArea_QHandleArray      # 4*DynArea_NumQHandles   ;1 word per quick handle
                                                    ; - if free, word = index of next free quick handle (or 0 if none)
                                                    ; - if used, word = ptr to DANode (must be > DynArea_NumQHandles)
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DynArea_AddrLookup        # 4<<DynArea_AddrLookupBits ; Lookup table for fast logaddr -> dynarea lookup
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;
DynArea_ws_size           *  :INDEX:@               ;must be multiple of 4
;
            ASSERT DynArea_QHandleArray = DynArea_FreeQHandles +4
  ]
;


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;        InsertDebugRoutines
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; Exit from ChangeDynamicArea with error Not all moved

failure_IRQgoingClearSemaphore
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        LDR     r0, =ZeroPage
      [ ZeroPage = 0
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        STR     r0, [r0, #CDASemaphore]
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      |
        MOV     r10, #0
        STR     r10, [r0, #CDASemaphore]
      ]
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failure_IRQgoing
        ADR     r0, ErrorBlock_ChDynamNotAllMoved
ChangeDynamic_Error
        MOV     r10, #0
        STR     r0, [stack]
        LDR     lr, [stack, #4*10]
        ORR     lr, lr, #V_bit
        STR     lr, [stack, #4*10]
CDS_PostServiceWithRestore
      [ International
        LDR     r0, [stack]
        BL      TranslateError
        STR     r0, [stack]
      ]

; and drop thru to ...

CDS_PostService
        MOV     r1, #Service_MemoryMoved
        MOV     r0, r10                 ; amount moved
        MOVS    r2, r11                 ; which way was transfer?
        BMI     %FT47                   ; [definitely a grow]
        CMP     r11, #ChangeDyn_FreePool
        BNE     %FT48                   ; [definitely a shrink]
        CMP     r12, #ChangeDyn_AplSpace
        BEQ     %FT48                   ; [a shrink]
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        RSB     r0, r0, #0             ; APLwork or free was source
        MOV     r2, r12                ; r2 = area indicator
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        BL      Issue_Service

        MOV     r1, r10                ; amount moved

        Pull    "r0, r2-r9, r10, lr"
        ExitSWIHandler

        MakeErrorBlock ChDynamNotAllMoved

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; in:   r0 = logical address where page is now

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GetPageFlagsForR0IntoR6 Entry "R0-R2, R4-R5, R7"
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;
; code from MoveCAMatR0toR3
;
        LDR     r5, =L2PT
        ADD     r4, r5, r0, LSR #10             ; r4 -> L2PT for log addr r0
        MOV     r2, r4, LSR #12
        LDR     r2, [r5, r2, LSL #2]            ; r2 = L2PT entry for r4
        TST     r2, #3                          ; if no page there
        BEQ     %FT90                           ; then cam corrupt

        LDR     r4, [r4]                        ; r4 = L2PT entry for r0
        TST     r4, #3                          ; check entry is valid too
        BEQ     %FT91
        MOV     r4, r4, LSR #12                 ; r4 = phys addr >> 12

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        LDR     r2, =ZeroPage
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        LDR     r6, [r2, #MaxCamEntry]
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        ADD     r5, r2, #PhysRamTable
      [ ZeroPage <> 0
        MOV     r2, #0
      ]
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        CMP     r2, r6                          ; if page we've got to is > max
        BHI     %FT92                           ; then corrupt
        LDMIA   r5!, {r7, lr}                   ; get phys.addr, size
        SUB     r7, r4, r7, LSR #12             ; number of pages into this bank
        CMP     r7, lr, LSR #12                 ; if too many
        ADDCS   r2, r2, lr, LSR #12             ; then advance physical page no.
        BCS     %BT10                           ; and loop

        ADD     r2, r2, r7                      ; add on number of pages within bank
;
; code from BangCamUpdate
;
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        LDR     r1, =ZeroPage
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        LDR     r1, [r1, #CamEntriesPointer]
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        ADD     r1, r1, r2, LSL #CAM_EntrySizeLog2 ; point at cam entry (logaddr, PPL)
        ASSERT  CAM_LogAddr=0
        ASSERT  CAM_PageFlags=4
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        LDMIA   r1, {r0, r6}                    ; r0 = current logaddress, r6 = current PPL
        EXIT

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        ADR     lr, NoL2ForPageBeingRemovedError ; NB don't corrupt r0 yet - we need that in block as evidence
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        STR     lr, [sp]                        ; update returned r0
        BL      StoreDebugRegs
        PullEnv                                 ; seriously broken memory
        SETV
        MOV     pc, lr

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        ADR     lr, PageBeingRemovedNotPresentError
        B       %BT95

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        ADR     lr, PhysicalAddressNotFoundError
        B       %BT95


; MoveCAMatR0toR3
; in:   r0 = old logaddr
;       r3 = new logaddr
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;       r9 = offset from 1st to 2nd copy of doubly mapped area (either source or dest, but not both)
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;       r11 = page protection level
;
; out:  r2 = physical page number of page moved, unless there was a serious error
;       r0,r1,r3,r6-r12 preserved
;       r4,r5 corrupted

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MoveCAMatR0toR3 Entry "r0,r1,r6,r7"
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        LDR     r5, =L2PT
        ADD     r4, r5, r0, LSR #10             ; r4 -> L2PT for log addr r0
        MOV     r2, r4, LSR #12
        LDR     r2, [r5, r2, LSL #2]            ; r2 = L2PT entry for r4
        TST     r2, #3                          ; if no page there
        BEQ     %FT90                           ; then cam corrupt

        LDR     r4, [r4]                        ; r4 = L2PT entry for r0
        TST     r4, #3                          ; check entry is valid too
        BEQ     %FT91
        MOV     r4, r4, LSR #12                 ; r4 = phys addr >> 12

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        LDR     r2, =ZeroPage
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        LDR     r6, [r2, #MaxCamEntry]
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        ADD     r5, r2, #PhysRamTable
      [ ZeroPage <> 0
        MOV     r2, #0
      ]
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        CMP     r2, r6                          ; if page we've got to is > max
        BHI     %FT92                           ; then corrupt
        LDMIA   r5!, {r7, lr}                   ; get phys.addr, size
        SUB     r7, r4, r7, LSR #12             ; number of pages into this bank
        CMP     r7, lr, LSR #12                 ; if too many
        ADDCS   r2, r2, lr, LSR #12             ; then advance physical page no.
        BCS     %BT10                           ; and loop

        ADD     r2, r2, r7                      ; add on number of pages within bank
        BL      BangCamUpdate
        CLRV
        EXIT

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        ADR     lr, NoL2ForPageBeingRemovedError ; NB don't corrupt r0 yet - we need that in block as evidence
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        STR     lr, [sp]                        ; update returned r0
        BL      StoreDebugRegs
        PullEnv                                 ; seriously broken memory
        SETV
        MOV     pc, lr

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        ADR     lr, PageBeingRemovedNotPresentError
        B       %BT95

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        ADR     lr, PhysicalAddressNotFoundError
        B       %BT95

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StoreDebugRegs ; Note: Corrupts R0,R1
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        Push    "lr"
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        LDR     lr, =ZeroPage+CamMapCorruptDebugBlock
        STMIA   lr, {r0-r12}
        STR     sp, [lr, #13*4]!
        LDMIA   sp, {r0,r1}                     ; reload stacked LR & return R0 (error pointer)
        STMIB   lr, {r0,r1}                     ; LR -> LR, error -> PC
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        Pull    "pc"

NoL2ForPageBeingRemovedError
        &       0
        =       "Memory Corrupt: No L2PT for page being removed", 0
        ALIGN

PageBeingRemovedNotPresentError
        &       0
        =       "Memory Corrupt: Page being removed was not present", 0
        ALIGN

PhysicalAddressNotFoundError
        &       0
        =       "Memory Corrupt: Physical address not found", 0
        ALIGN

CamMapBroke
        &       0
        =       "!!!! CAM Map Corrupt !!!!", 0
        ALIGN
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; Call_CAM_Mapping
; in:   r2 = physical page number
;       r3 = logical address (2nd copy of doubly mapped area)
;       r9 = offset from 1st to 2nd copy of doubly mapped area (either source or dest, but not both)
;       r11 = PPL + CB bits
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Call_CAM_Mapping
        Push    "r0, r1, r4, r6, lr"
        BL      BangCamUpdate
        Pull    "r0, r1, r4, r6, pc"

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  [ FastCDA_Bulk
; RemoveCacheabilityR0ByMinusR2
; Make a range of pages (temporarily) uncacheable prior to (re)moving them
; Doesn't perform any cache/TLB maintenance
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; in:   r0 = end of area
;       r2 = size of area (must be nonzero)
; out:  r6 has DynAreaFlags_NotCacheable set if entire region noncacheable
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;              Flag clear if at least one page was cacheable
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;       r0 points to start of area
;
;       4K page size assumed!
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RemoveCacheabilityR0ByMinusR2 ROUT
        Entry   "r1-r5"
        MOV     r5, #DynAreaFlags_NotCacheable
        MOV     r1, #-1
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        SUB     r0, r0, #4096
        BL      GetPageFlagsForR0IntoR6
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        TST     r6, #DynAreaFlags_NotCacheable
        BNE     %FT90
        ; Work out required page flags - use cached flags from last page if possible
        CMP     r1, r6
        BEQ     %FT20
        LDR     r3, =ZeroPage
        MOV     r1, r6
        LDR     r3, [r3, #MMU_PCBTrans]
        GetTempUncache r4, r6, r3, lr
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        ; Update the current L2PT entry
        LDR     r3, =L2PT
        LDR     lr, =TempUncache_L2PTMask
        LDR     r5, [r3, r0, LSR #10]
        BIC     r5, r5, lr
        ORR     r5, r5, r4
        STR     r5, [r3, r0, LSR #10]
        ; Clear the flag from R5
        MOV     r5, #0
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        SUBS    r2, r2, #4096
        BNE     %BT10
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        MOV     r6, r5
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        EXIT
  ]
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; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; In    r0 bits 0..6 = area number
;       r0 bit 7 set => return max area size in r2 (implemented 13 Jun 1990)
;                       this will return an error if not implemented
; Out   r0 = address of area
;       r1 = current size of area
;       r2 = max size of area if r0 bit 7 set on entry (preserved otherwise)

; TMD 19-May-93: When this is updated to new CDA list, change meaning as follows:

; r0 in range 0..&7F    return address, size of area r0
;             &80..&FF  return address, size, maxsize of area (r0-&80)
;             &100..    return address, size, maxsize of area r0

; TMD 20-Aug-93: New bit added - if r0 = -1 on entry, then returns info on application space
; r0 = base address (&8000)
; r1 = current size (for current task)
; r2 = maximum size (eg 16M-&8000)

ReadDynamicArea ROUT

readdyn_returnR2bit     *       &80
        ASSERT  ChangeDyn_MaxArea < readdyn_returnR2bit

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        CMP     r0, #ChangeDyn_AplSpace         ; if finding out about app space
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      [ ZeroPage = 0
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        LDREQ   r1, [r0, #AplWorkSize+1]        ; then r1 = current size
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      |
        LDREQ   r1, =ZeroPage
        LDREQ   r1, [r1, #AplWorkSize]
      ]
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        LDREQ   r2, =AplWorkMaxSize             ; and r2 = max size
        MOVEQ   r0, #&8000                      ; r0 = base address
        SUBEQ   r1, r1, r0                      ; adjust size and maxsize
        SUBEQ   r2, r2, r0                      ; to remove bottom 32K
        ExitSWIHandler EQ

; first check if it's one of the new ones

        Push    "r1,lr"
        CMP     r0, #&100                       ; if area >= &100
        MOVCS   r1, r0                          ; then just use area
        BICCC   r1, r0, #readdyn_returnR2bit    ; else knock off bit 7
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  [ DynArea_QuickHandles
        BL      QCheckAreaNumber                ; out: r10 -> node
  |
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        BL      CheckAreaNumber                 ; out: r10 -> node
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  ]
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        Pull    "r1,lr"
        BCC     %FT05                           ; [not a new one, so use old code]

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        LDR     r11, [r10, #DANode_Flags]
        TST     r11, #DynAreaFlags_PMP
        BNE     %FT01
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        CMP     r0, #&80                        ; CS => load maxsize into R2
                                                ; (do this either if bit 7 set, or area >=&100)
        LDRCS   r2, [r10, #DANode_MaxSize]
        LDR     r1, [r10, #DANode_Size]         ; r1 = current size
        LDR     r0, [r10, #DANode_Base]         ; r0 -> base
        TST     r11, #DynAreaFlags_DoublyMapped
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        SUBNE   r0, r0, r1                      ; if doubly mapped then return start of 1st copy for compatibility
        ExitSWIHandler
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        ; Convert physical parameters into byte counts
        CMP     r0, #&80
        BCC     %FT02
        LDR     r2, [r10, #DANode_PMPMaxSize]
        CMP     r2, #DynArea_PMP_BigPageCount
        MOVLO   r2, r2, LSL #12
        LDRHS   r2, =DynArea_PMP_BigByteCount
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        LDR     r1, [r10, #DANode_PMPSize]
        CMP     r1, #DynArea_PMP_BigPageCount
        MOVLO   r1, r1, LSL #12
        LDRHS   r1, =DynArea_PMP_BigByteCount
        LDR     r0, [r10, #DANode_Base]
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        ExitSWIHandler
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        ADRL    r0, ErrorBlock_BadDynamicArea
      [ International
        Push    "lr"
        BL      TranslateError
        Pull    "lr"
      ]
        B       SLVK_SetV

        MakeErrorBlock  BadDynamicArea

; *************************************************************************
; User access to CAM mapping
; ReadMemMapInfo:
; returns R0 = pagsize
;         R1 = number of pages in use  (= R2 returned from SetEnv/Pagesize)
; *************************************************************************

ReadMemMapInfo_Code
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      LDR      R10, =ZeroPage
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      LDR      R0, [R10, #Page_Size]
      LDR      R1, [R10, #RAMLIMIT]    ; = total memory size
      ADRL     R11, PageShifts-1
      LDRB     R11, [R11, R0, LSR #12]
      MOV      R1, R1, LSR R11
      ExitSWIHandler

; ************************************************************************
; SWI ReadMemMapEntries: R0 pointer to list.
;  Entries are three words long, the first of which is the CAM page number.
;  List terminated by -1.
; Returns pagenumber (unaltered)/address/PPL triads as below
; ************************************************************************

ReadMemMapEntries_Code  ROUT
        Push    "r0,r14"
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        LDR     r14, =ZeroPage
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        LDR     r10, [r14, #CamEntriesPointer]
        LDR     r14, [r14, #MaxCamEntry]
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        LDR     r12, [r0], #4                   ; page number
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        CMP     r12, r14
        Pull    "r0,r14", HI
        ExitSWIHandler HI
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   [ ChocolateAMB
        ;may need AMB to make mapping honest (as if not lazy), if page is in currently mapped app
        Push    "r0, lr"
        MOV     r0, r12                         ; page number to make honest
        BL      AMB_MakeHonestPN
        Pull    "r0, lr"
   ]

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        ADD     r11, r10, r12, LSL #CAM_EntrySizeLog2
        ASSERT  CAM_LogAddr=0
        ASSERT  CAM_PageFlags=4
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        LDMIA   r11, {r11, r12}
        STMIA   r0!, {r11, r12}
        B       %BT01

; ************************************************************************
; SWI FindMemMapEntries:
; In:  R0 -> table of 12-byte page entries
;       +0      4       probable page number (0..npages-1) (use 0 if no idea)
;       +4      4       logical address to match with
;       +8      4       undefined
;       terminated by a single word containing -1
;
; Out: table of 12-byte entries updated:
;       +0      4       actual page number (-1 => not found)
;       +4      4       address (preserved)
;       +8      4       page protection level (3 if not found)
;       terminator preserved
;
; ************************************************************************

FindMemMapEntries_Code  ROUT

; Code for expanded CAM map version

        Push    "r0, r9, r14"
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        LDR     r14, =ZeroPage
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        LDR     r9, [r14, #MaxCamEntry]
        LDR     r14, [r14, #CamEntriesPointer]  ; r14 -> start of cam map
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        ADD     r9, r14, r9, LSL #CAM_EntrySizeLog2 ; r9 -> first word of last entry in cam map
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        LDR     r10, [r0, #0]                   ; r10 = guess page number (or -1)
        CMP     r10, #-1                        ; if -1 then end of list
        Pull    "r0, r9, r14", EQ               ; so restore registers
        ExitSWIHandler EQ                       ; and exit

        LDR     r11, [r0, #4]                   ; r11 = logical address
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   [ ChocolateAMB
        ;may need AMB to make mapping honest (as if not lazy), if page is in currently mapped app
        Push    "r0, lr"
        MOV     r0, r11                         ; logical address to make honest
        BL      AMB_MakeHonestLA                ; note, quickly dismisses non app space addresses
        Pull    "r0, lr"
   ]

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        ADD     r10, r14, r10, LSL #CAM_EntrySizeLog2 ; form address with 'guess' page
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        CMP     r10, r9                         ; if off end of CAM
        BHI     %FT20                           ; then don't try to use the guess

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        LDR     r12, [r10, #CAM_LogAddr]        ; load address from guessed page
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        TEQ     r11, r12                        ; compare address
        BEQ     %FT60                           ; if equal, then guessed page was OK
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; for now, cheat by looking in L2PT, to see if we can speed things up

        Push    "r5-r8"                         ; need some registers here!
        LDR     r10, =L2PT
        MOV     r8, r11, LSR #12                ; r8 = logical page number
        ADD     r8, r10, r8, LSL #2             ; r8 -> L2PT entry for log.addr
        MOV     r5, r8, LSR #12                 ; r5 = page offset to L2PT entry for log.addr
        LDR     r5, [r10, r5, LSL #2]           ; r5 = L2PT entry for L2PT entry for log.addr
        TST     r5, #3                          ; if page not there
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        SUBEQ   r10, r9, #CAM_EntrySizeLog2     ; then invalid page so go from last one
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        BEQ     %FT45
        LDR     r8, [r8]                        ; r8 = L2PT entry for log.addr
        MOV     r8, r8, LSR #12                 ; r8 = physaddr / 4K

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        LDR     r5, =ZeroPage+PhysRamTable
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        SUB     r10, r14, #CAM_EntrySize
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        CMP     r10, r9                         ; have we run out of RAM banks?
        BCS     %FT40                           ; then fail
        LDMIA   r5!, {r6,r7}                    ; load next address, size
        SUB     r6, r8, r6, LSR #12             ; number of pages into this bank
        CMP     r6, r7, LSR #12                 ; if more than there are
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        ASSERT  CAM_EntrySizeLog2 <= 16
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        BICCS   r7, r7, #&F00
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        ADDCS   r10, r10, r7, LSR #12-CAM_EntrySizeLog2 ; then advance CAM entry position
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        BCS     %BT30                           ; and loop to next bank

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        ADD     r10, r10, r6, LSL #CAM_EntrySizeLog2 ; advance by 2 words for each page in this bank
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        SUBCS   r10, r9, #CAM_EntrySize         ; search from last one, to fail quickly (if CS)
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        Pull    "r5-r8"
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        CMP     r10, r9                         ; if not just done last one,
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        ASSERT  CAM_LogAddr=0
        LDRNE   r12, [r10, #CAM_EntrySize]!     ; then get logical address
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        TEQNE   r11, r12                        ; compare address
        BNE     %BT50                           ; loop if not same and not at end

; either found page or run out of pages

        TEQ     r11, r12                        ; see if last one matched
                                                ; (we always load at least one!)
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        LDREQ   r12, [r10, #CAM_PageFlags]      ; if match, then r12 = PPL
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        SUBEQ   r10, r10, r14                   ; and page number=(r10-r14)>>3
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        MOVEQ   r10, r10, LSR #CAM_EntrySizeLog2
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        MOVNE   r10, #-1                        ; else unknown page number indicator
        MOVNE   r12, #3                         ; and PPL=3 (no user access)

        STMIA   r0!, {r10-r12}                  ; store all 3 words
        B       %BT10                           ; and go back for another one

;**************************************************************************
; SWI SetMemMapEntries: R0 pointer to list of CAM page/address/PPL triads,
;  terminated by -1.
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; address of -1 means "put the page out of the way"
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; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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; note, if ChocolateAMB, no MakeHonest consideration here, this SWI just
; changes the mapping of pages regardless of their current mapping, and
; assumes the caller knows what he is doing (ho ho)
;

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SetMemMapEntries_Code  ROUT
        Push    "r0-r6, r9, lr"
        MOV     r12, r0

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; BangCamUpdate takes entry no in r2, logaddr to set to in r3, r11 = PPL
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; corrupts r0,r1,r4,r6

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        LDR     r9, =ZeroPage
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        LDR     r5, [r9, #MaxCamEntry]
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        LDR     r9, [r9, #CamEntriesPointer]
        ADD     r9, r9, #CAM_PageFlags
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        LDR     r2, [r12], #4
        CMP     r2, r5
        BHI     %FT02                   ; finished
        LDMIA   r12!, {r3, r11}
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 [ {FALSE}
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        AND     r11, r11, #3
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        CMP     r3, #-1
        LDRHS   r3, =DuffEntry
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        MOVHS   r11, #AreaFlags_Duff
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        ; Ensure PMP membership flag is retained - just in case caller doesn't
        ; know what he's doing
        LDR     r0, [r9, r2, LSL #CAM_EntrySizeLog2]
        AND     r0, r0, #DynAreaFlags_PMP
        BIC     r11, r11, #DynAreaFlags_PMP
        ORR     r11, r11, r0
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        BL      BangCamUpdate
        B       %BT01
02
        Pull    "r0-r6, r9, lr"
        ExitSWIHandler

        LTORG



;**************************************************************************
;
;       DynamicAreaSWI - Code to handle SWI OS_DynamicArea
;
; in:   r0 = reason code
;       Other registers depend on reason code
;
; out:  Depends on reason code
;

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DynArea_NewAreas *      &100            ; Allocated area numbers start here
DynArea_NewAreasBase *  &04000000       ; Allocated area addresses start here
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DynArea_PMP_BigPageCount * 1:SHL:(31-12) ; If PMP has >= this many pages...
DynArea_PMP_BigByteCount * &7FFFF000     ; Then convert to this byte value
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;
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; Internal page flags (note - may overlap DA flags)
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;
TempUncacheableShift            * 16
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PageFlags_TempUncacheableBits   * 15 :SHL: TempUncacheableShift    ; temporary count of uncacheability, used by DMA mgr (via OS_Memory 0)
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PageFlags_Required              *  1 :SHL: 21                      ; physical page asked for by handler (only set temporarily)

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;
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; Temporary flags only used by kernel (note - may overlap DA flags)
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;
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PageFlags_Unsafe                *  1 :SHL: 31                      ; skip cache/TLB maintenance in BangCamUpdate. flag not saved to CAM map.

; Mask to convert DANode_Flags to page flags
DynAreaFlags_AccessMask * DynAreaFlags_APBits :OR: DynAreaFlags_NotBufferable :OR: DynAreaFlags_NotCacheable :OR: DynAreaFlags_DoublyMapped :OR: DynAreaFlags_CPBits :OR: DynAreaFlags_PMP
; PMP LogOp can specify these flags
DynAreaFlags_PMPLogOpAccessMask * (DynAreaFlags_AccessMask :OR: PageFlags_Unavailable) :AND: :NOT: (DynAreaFlags_DoublyMapped :OR: DynAreaFlags_PMP)
; PMP PhysOp can specify these flags
DynAreaFlags_PMPPhysOpAccessMask * PageFlags_Unavailable
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DynamicAreaSWI Entry
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        BL      DynAreaSub
        PullEnv
        ORRVS   lr, lr, #V_bit
        ExitSWIHandler

DynAreaSub
        CMP     r0, #DAReason_Limit
        ADDCC   pc, pc, r0, LSL #2
        B       DynArea_Unknown
        B       DynArea_Create
        B       DynArea_Remove
        B       DynArea_GetInfo
        B       DynArea_Enumerate
        B       DynArea_Renumber
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 [ ShrinkableDAs
        B       DynArea_ReturnFree
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 |
        B       DynArea_Unknown
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 [ DynArea_QuickHandles
        B       DynArea_GetChangeInfo
        B       DynArea_EnumerateInfo
        B       DynArea_SetClamps
 |
        B       DynArea_Unknown
        B       DynArea_Unknown
        B       DynArea_Unknown
 ]
 [ DA_Batman
        B       DynArea_SparseClaim
        B       DynArea_SparseRelease
 |
        B       DynArea_Unknown
        B       DynArea_Unknown
 ]
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        B       DynArea_Unknown ; 11
        B       DynArea_Unknown ; |
        B       DynArea_Unknown ; |
        B       DynArea_Unknown ; |
        B       DynArea_Unknown ; |--Reserved for ROL
        B       DynArea_Unknown ; |
        B       DynArea_Unknown ; |
        B       DynArea_Unknown ; |
        B       DynArea_Unknown ; 19
        B       DynArea_Locate
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        B       DynArea_PMP_PhysOp
        B       DynArea_PMP_LogOp
        B       DynArea_PMP_Resize
        B       DynArea_PMP_GetInfo
        B       DynArea_PMP_GetPages
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;
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; unknown OS_DynamicArea reason code
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;
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DynArea_Unknown
        ADRL    r0, ErrorBlock_HeapBadReason
DynArea_TranslateAndReturnError
      [ International
        Push    lr
        BL      TranslateError
        Pull    lr
      ]
DynArea_ReturnError
        SETV
        MOV     pc, lr

;**************************************************************************
;
;       DynArea_Create - Create a dynamic area
;
;       Internal routine called by DynamicAreaSWI and by reset code
;
; in:   r0 = reason code (0)
;       r1 = new area number, or -1 => RISC OS allocates number
;       r2 = initial size of area (in bytes)
;       r3 = base logical address of area, or -1 => RISC OS allocates address space
;       r4 = area flags
;               bits 0..3 = access privileges
;               bit  4 = 1 => not bufferable
;               bit  5 = 1 => not cacheable
;               bit  6 = 0 => area is singly mapped
;                      = 1 => area is doubly mapped
;               bit  7 = 1 => area is not user draggable in TaskManager window
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;               bit  8 = 1 => area may require specific physical pages
;               bit  9 = 1 => area is shrinkable (only implemented if ShrinkableDAs)
;               bit 10 = 1 => area may be sparsely mapped (only implemented if DA_Batman)
;               bit 11 = 1 => area is bound to client application (allows areas to be overlayed in address space)
;                             not implemented yet, but declared in public API for Ursula
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;               bits 12..14 => cache policy (if bits 4 or 5 set)
;               bit 15 = 1 => area requires DMA capable pages (is bit 12 in ROL's OS!)
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;               bits 16-19 used by ROL
;               bit 20 = 1 => area is backed by physical memory pool
;               other bits reserved for future expansion + internal page flags (should be 0)
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;
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;       r5 = maximum size of logical area, or -1 for total RAM size
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;       r6 -> area handler routine
;       r7 = workspace pointer for area handler (-1 => use base address)
;       r8 -> area description string (null terminated) (gets copied)
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;       r9 = initial physical area size limit, in pages (physical memory pools), otherwise ignored
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;
; out:  r1 = given or allocated area number
;       r3 = given or allocated base address of area
;       r5 = given or allocated maximum size
;       r0, r2, r4, r6-r9 preserved
;       r10-r12 may be corrupted
;

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DynArea_Create Entry "r2,r6-r8"
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        CMP     r1, #-1         ; do we have to allocate a new area number
        BEQ     %FT10

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  [ DynArea_QuickHandles
        CMP     r1, #DynArea_NewAreas
        BLO     %FT06
        CMP     r1, #DynArea_NewAreas+DynArea_NumQHandles
        BLO     %FT08           ; can't choose your own quick handle
  ]

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  [ DynArea_QuickHandles
        BL      QCheckAreaNumber ; see if area number is unique
  |
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        BL      CheckAreaNumber ; see if area number is unique
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  ]
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        BCC     %FT20           ; didn't find it, so OK

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        ADR     r0, ErrorBlock_AreaAlreadyExists
DynArea_ErrorTranslateAndExit
        PullEnv
        B       DynArea_TranslateAndReturnError

        MakeErrorBlock  AreaAlreadyExists
        MakeErrorBlock  AreaNotOnPageBdy
        MakeErrorBlock  OverlappingAreas
        MakeErrorBlock  CantAllocateArea
        MakeErrorBlock  CantAllocateLevel2
        MakeErrorBlock  UnknownAreaHandler
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        MakeErrorBlock  BadDynamicAreaOptions
        MakeErrorBlock  BadPageNumber
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; we have to allocate an area number for him

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  [ DynArea_QuickHandles
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        LDR     r11, =ZeroPage
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        LDR     r11, [r11, #DynArea_ws ]
        LDR     r1, DynArea_FreeQHandles          ;get index of next available quick handle, if any free
        CMP     r1, #0
        ADDNE   r1, r1, #DynArea_NewAreas-1       ;compute quick handle from index
        BNE     %FT20
        LDR     r1, DynArea_TreacleGuess          ;last non-quick number allocated
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        ADD     r1, r1, #1                        ; increment for next guess (collisions should be *very* rare)
        CMP     r1, #DynArea_NewAreas+DynArea_NumQHandles
        MOVLO   r1, #DynArea_NewAreas+DynArea_NumQHandles
        BL      QCheckAreaNumber
        BCS     %BT12                             ; and try again
  |
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        MOV     r1, #DynArea_NewAreas
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        BL      CheckAreaNumber
        ADDCS   r1, r1, #1      ; that area number already exists, so increment
        BCS     %BT12           ; and try again
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  ]

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; Check PMP settings
; If PMP is requested:
; * Must require specific pages
; * Mustn't be sparse
; * Mustn't be doubly mapped
; * Mustn't be requesting DMA auto-alloc
; * Must be zero initial size
; * Must have handler code
; Some of these restrictions may be lifted in future (e.g. if not requesting specific pages, kernel could implement OS_ChangeDynamicArea?)
        TST     r4, #DynAreaFlags_PMP
        BEQ     %FT21
        LDR     r11, =DynAreaFlags_DoublyMapped+DynAreaFlags_NeedsSpecificPages+DynAreaFlags_SparseMap+DynAreaFlags_NeedsDMA
        AND     r11, r4, r11
        TEQ     r11, #DynAreaFlags_NeedsSpecificPages
        TEQEQ   r2, #0
        ADRNE   r0, ErrorBlock_BadDynamicAreaOptions
        BNE     DynArea_ErrorTranslateAndExit
        TEQ     r6, #0
        ADREQ   r0, ErrorBlock_BadDynamicAreaOptions
        BEQ     DynArea_ErrorTranslateAndExit
21

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; now validate maximum size of area

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  [ DynArea_QuickHandles
    ;
    ; apply clamps on max size, as set by last call to OS_DynamicArea 8
    ;
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        LDR     r11, =ZeroPage
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        LDR     r11, [r11, #DynArea_ws]
    [ DA_Batman
        TST     r4, #DynAreaFlags_SparseMap
        BEQ     DAC_notsparse
        LDR     r10, DynArea_OD8Clamp3   ; clamp for sparse dynamic area
        CMP     r5, r10                  ; if requested max size is > relevant clamp
        MOVHI   r5, r10                  ; then clamp it!
        LDR     r10, [sp]                ; requested initial size, from stack
        CMP     r5, r10
        MOVLO   r5, r10                  ; we must try to honour initial size (allowed to break clamp)
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        LDR     r10, =ZeroPage
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        LDR     r11, [r10, #Page_Size]
        B       DAC_roundup
DAC_notsparse
    ]
        CMP     r5, #-1
        LDREQ   r10, DynArea_OD8Clamp1   ; clamp for max size requested of -1
        LDRNE   r10, DynArea_OD8Clamp2   ; clamp for max size requested of some specific value
        CMP     r5, r10                  ; if requested max size is > relevant clamp
        MOVHI   r5, r10                  ; then clamp it!
        LDR     r10, [sp]                ; requested initial size, from stack
        CMP     r5, r10
        MOVLO   r5, r10                  ; we must try to honour initial size (allowed to break clamp)
  ]

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        LDR     r10, =ZeroPage
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        LDR     r11, [r10, #Page_Size]
        LDR     r10, [r10, #RAMLIMIT]   ; get total RAM size
        CMP     r5, r10                 ; if requested maximum size is > total
        MOVHI   r5, r10                 ; then set max to total (NB. -1 passed in always yields HI)

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DAC_roundup
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        SUB     r10, r11, #1            ; also round up to a page multiple
        ADD     r5, r5, r10
        BIC     r5, r5, r10

; now see if we have to allocate a logical address space
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        TEQ     r5, #0                  ; If no logical size (i.e. purely physical PMP)
        MOVEQ   r3, #0                  ; Then set base addr to 0
        BEQ     %FT41                   ; And skip straight to claiming the DANode
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        CMP     r3, #-1                 ; if we are to allocate the address space
        BEQ     %FT30                   ; then go do it

; otherwise we must check that the address does not clash with anything else

        TST     r3, r10                         ; does it start on a page boundary
        ADRNE   r0, ErrorBlock_AreaNotOnPageBdy ; if not then error
        BNE     DynArea_ErrorTranslateAndExit

        BL      CheckForOverlappingAreas        ; in: r3 = address, r4 = flags, r5 = size; out: if error, r0->error, V=1
        BVC     %FT40
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        PullEnv
        B       DynArea_ReturnError

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        BL      AllocateAreaAddress             ; in: r4 = flags, r5 = size of area needed; out: r3, or V=1, r0->error
        BVS     %BT25
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        BL      AllocateBackingLevel2           ; in: r3 = address, r4 = flags, r5 = size; out: VS if error
        BVS     %BT25

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        Push    "r0,r1,r3"
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  [ DynArea_QuickHandles
    ;we save work and reduce stress on system heap by claiming only one block, consisting of node followed by
    ;string space (always maximum length, but typically not overly wasteful compared to 2nd block overhead)
    ;
        MOV     r3, #DANode_NodeSize + DynArea_MaxNameLength + 1
  |
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        MOV     r3, #DANode_NodeSize
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  ]
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        BL      ClaimSysHeapNode                ; out: r2 -> node
        STRVS   r0, [sp]
        Pull    "r0,r1,r3"
        BVS     %BT25                           ; failed to claim node

; now store data in node (could probably use STM if we shuffled things around)

        CMP     r7, #-1                         ; if workspace ptr = -1
        MOVEQ   r7, r3                          ; then use base address

        STR     r1, [r2, #DANode_Number]
        STR     r3, [r2, #DANode_Base]
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  [ DA_Batman
        ;disallow some awkward flag options if SparseMap set (no error), and temporarily create as not sparse
        ;also disallow a DA handler
        TST     r4, #DynAreaFlags_SparseMap
        STREQ   r4, [r2, #DANode_Flags]
        BICNE   r7, r4, #DynAreaFlags_DoublyMapped + DynAreaFlags_NeedsSpecificPages + DynAreaFlags_Shrinkable + DynAreaFlags_SparseMap
        ORRNE   r7, r7, #DynAreaFlags_NotUserDraggable
        STRNE   r7, [r2, #DANode_Flags]
        MOVNE   r6, #0
        MOVNE   r7, #0
  |
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        STR     r4, [r2, #DANode_Flags]
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  ]
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        STR     r5, [r2, #DANode_MaxSize]
        STR     r6, [r2, #DANode_Handler]
        STR     r7, [r2, #DANode_Workspace]
        MOV     r7, #0                          ; initial size is zero
        STR     r7, [r2, #DANode_Size]          ; before we grow it
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        TST     r4, #DynAreaFlags_PMP
        STR     r7, [r2, #DANode_PMP]
        STREQ   r7, [r2, #DANode_PMPMaxSize]
        STR     r7, [r2, #DANode_PMPSize]
        BEQ     %FT44
        STR     r3, [r2, #DANode_SparseHWM]
        TEQ     r9, #0
        STR     r9, [r2, #DANode_PMPMaxSize]
        BEQ     %FT44
        ; Allocate and initialise PMP for this DA
        Push    "r0-r3"
        LDR     r0, =ZeroPage
        LDR     r0, [r0, #MaxCamEntry]
        CMP     r9, r0
        ADDHI   r9, r0, #1
        MOV     r3, r9, LSL #2
        BL      ClaimSysHeapNode
        BVS     %FT43
        MOV     r10, r2
        MOV     r0, #-1
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        SUBS    r3, r3, #4
        STR     r0, [r2], #4
        BNE     %BT42
        Pull    "r0-r3"
        STR     r10, [r2, #DANode_PMP]
        B       %FT44
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        STR     r0, [sp]
        LDR     r2, [sp, #8]
        BL      FreeSysHeapNode
        Pull    "r0-r3"
        SETV
        B       %BT25
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        ; update lower limit on IO space growth, if this DA exceeds previous limit
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      [ ZeroPage <> 0
        LDR     r7, =ZeroPage
      ]
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        LDR     r6, [r7, #IOAllocLimit]
        ADD     lr, r3, r5
        CMP     lr, r6
        STRHI   lr, [r7, #IOAllocLimit]

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; now make copy of string - first find out length of string

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  [ DynArea_QuickHandles

        ADD     r7, r2, #DANode_NodeSize
        STR     r7, [r2, #DANode_Title]
        Push    "r0"
        MOV     r0, #DynArea_MaxNameLength
        TEQ     r8, #0
    [ DynArea_NullNamePtrMeansHexString
        ASSERT  DynArea_MaxNameLength > 8
        BNE     %FT45
        Push    "r1, r2"
        MOV     r0, r1                          ;string is 8-digit hex of DA number
        MOV     r1, r7
        MOV     r2, #DynArea_MaxNameLength+1
        SWI     XOS_ConvertHex8
        Pull    "r1, r2"
        B       %FT55
    |
        BEQ     %FT50                           ;assume NULL ptr to mean no DA name
    ]
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        LDRB    r6, [r8], #1
        STRB    r6, [r7], #1
        SUB     r0, r0, #1
        TEQ     r6, #0
        TEQNE   r0, #0
        BNE     %BT45
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        MOV     r0, #0
        STRB    r0, [r7], #1
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        Pull    "r0"

  |

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        MOV     r7, r8
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        LDRB    r6, [r7], #1
        TEQ     r6, #0
        BNE     %BT45

        Push    "r0-r3"
        SUB     r3, r7, r8                      ; r3 = length inc. term.
        BL      ClaimSysHeapNode
        STRVS   r0, [sp]
        MOV     r7, r2
        Pull    "r0-r3"
        BVS     StringNodeClaimFailed

        STR     r7, [r2, #DANode_Title]
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        LDRB    r6, [r8], #1                    ; copy string into claimed block
        STRB    r6, [r7], #1
        TEQ     r6, #0
        BNE     %BT50

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 ] ;DynArea_QuickHandles

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; now put node on list - list is sorted in ascending base address order

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        LDR     r8, =ZeroPage+DAList
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        LDR     r6, [r2, #DANode_Base]
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        MOV     r7, r8
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        ASSERT  DANode_Link = 0                 ; For picking up pointer to first real node
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        LDR     r8, [r7, #DANode_Link]          ; get next node
        TEQ     r8, #0                          ; if no more
        BEQ     %FT70                           ; then put it on here
        LDR     lr, [r8, #DANode_Base]
        CMP     lr, r6                          ; if this one is before ours
        BCC     %BT60                           ; then loop

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        STR     r8, [r2, #DANode_Link]
        STR     r2, [r7, #DANode_Link]

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  [ DynArea_QuickHandles
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        LDR     r11, =ZeroPage
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        LDR     r11, [r11, #DynArea_ws]
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        BL      AddDAToAddrLookupTable
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        ;so XOS_ChangeDynamicArea can pick up the node we are still creating
        STR     r1, DynArea_CreatingHandle
        STR     r2, DynArea_CreatingPtr
        ;so initial grow won't leave resize signature
        LDR     lr, DynArea_OD6Signature
        ORR     lr, lr, #&80000000
        STR     lr, DynArea_OD6Signature
  ]

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; now we need to grow the area to its requested size

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        Push    "r0, r1, r2"
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        LDR     r0, [r2, #DANode_Number]
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        LDR     r1, [sp, #3*4]                  ; reload requested size off stack
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        CMP     r1, #0                          ; skip redundant SWI
        SWINE   XOS_ChangeDynamicArea           ; deal with error - r0,r1,r2 still stacked
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        BVS     %FT90
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        Pull    "r0, r1, r2"

  [ DynArea_QuickHandles
;
; Now put node on alphabetically sorted list
;
        Push    "r3,r4,r5,r7,r8,r9"
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        LDR     r11, =ZeroPage
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        LDR     r11, [r11, #DynArea_ws]
        ADR     r8, DynArea_SortedList - DANode_SortLink ;so that [r8, #DANode_SortLink] addresses list header)
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        MOV     r7, r8                       ; previous
        LDR     r8, [r7, #DANode_SortLink]
        TEQ     r8, #0
        BEQ     %FT78
        ;ho hum, UK case insensitive string compare
        LDR     r3, [r2, #DANode_Title]
        LDR     r9, [r8, #DANode_Title]
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        LDRB    r4, [r3],#1
        uk_LowerCase r4,r11
        LDRB    r5, [r9],#1
        uk_LowerCase r5,r11
        CMP     r4, r5
        BNE     %FT77
        CMP     r4, #0
        BNE     %BT76
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        BHI     %BT75
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        STR     r2, [r7, #DANode_SortLink]
        STR     r8, [r2, #DANode_SortLink]
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        Pull    "r3,r4,r5,r7,r8,r9"
  ] ;DynArea_QuickHandles

  [ DA_Batman
        TST     r4, #DynAreaFlags_SparseMap
        LDRNE   r11, [r2, #DANode_Flags]
        ORRNE   r11, r11, #DynAreaFlags_SparseMap ; set this in node now (after initial grow)
        STRNE   r11, [r2, #DANode_Flags]
        LDRNE   r11, [r2, #DANode_Size]
        LDRNE   lr,  [r2, #DANode_Base]
        ADDNE   r11, r11, lr
        STRNE   r11, [r2, #DANode_SparseHWM]      ; initial high water mark
  ]

  [ DynArea_QuickHandles
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        LDR     r11, =ZeroPage
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        LDR     r11, [r11, #DynArea_ws]

        TST     r4, #DynAreaFlags_Shrinkable
        LDRNE   lr, DynArea_ShrinkableSubList
        STRNE   lr, [r2, #DANode_SubLink]
        STRNE   r2, DynArea_ShrinkableSubList   ;link onto front of Shrinkable sublist if Shrinkable

        MOV     lr, #-1
        STR     lr, DynArea_CreatingHandle      ;invalidate this now
        CMP     r1, #ChangeDyn_MaxArea
        BHI     %FT72
        ADR     lr, DynArea_SysQHandleArray
        STR     r2, [lr, r1, LSL #2]            ;system handle - store ptr to node for quick reference
        B       %FT80
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        LDR     lr, DynArea_OD6Signature
        STR     lr, DynArea_OD6PrevSignature
        ORR     lr, lr, #1
        STR     lr, DynArea_OD6Signature
        STR     r1, DynArea_OD6Handle
        CMP     r1, #DynArea_NewAreas
        BLO     %FT80
        CMP     r1, #DynArea_NewAreas+DynArea_NumQHandles
        BHS     %FT74
        SUB     r10, r1, #DynArea_NewAreas
        ADR     lr, DynArea_QHandleArray
        LDR     r6, [lr, r10, LSL #2]           ;pick up index of next free quick handle
        STR     r6, DynArea_FreeQHandles        ;store as index of first free quick handle
        STR     r2, [lr, r10, LSL #2]           ;store ptr to node for quick reference
        B       %FT80
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        LDR     r10, DynArea_TreacleGuess
        ADD     r10, r10, #1
        STR     r10, DynArea_TreacleGuess       ;non-quick handle allocated, increment for next allocate
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  ] ;DynArea_QuickHandles

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; Now issue service to tell TaskManager about it

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        Push    "r0, r1, r2"
        MOV     r2, r1                          ; r2 = area number
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        MOV     r1, #Service_DynamicAreaCreate
        BL      Issue_Service
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        Pull    "r0, r1, r2"
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