Middle

; 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     => Middle

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; VecRdLine - Read line from input stream (OSWORD 0 equivalent)

; In    r0 -> buffer for characters
;       r1 = max length of line (excluding carriage return)
;       r2 = lowest character put into buffer
;       r3 = highest character put into buffer
;       wp -> OsbyteVars

; Out   r1 = length of line (excluding carriage return)
;       C=0 => line terminated by return (CR or LF)
;       C=1 => line terminated by ESCAPE

; ReadLine: suggested extensions (available RSN)
;
; are 1) stopping it reflecting control characters/characters not put in the
;        buffer
;     2) making any reflection print a given character (for hiding passwords
;        etc
;
; So, definition is :
;
; Top byte R0 contains flags :
;   Bit 31 set means don't reflect characters that don't go in the buffer
;   Bit 30 set means reflect with the character in R4
; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

VecRdLine ROUT

        Push    "R4-R7"
        AND     R7, R0, #&C0000000      ; extract flags
        AND     R4, R4, #&FF
        ORR     R7, R7, R4              ; got flags, potential echo byte in R7

        BIC     R4, R0, #ARM_CC_Mask-3  ; R4 -> buffer

        MOV     R6, #0                  ; R6 = index into buffer
        STRB    R6, PageModeLineCount   ; reset page lines

        B       %FT10
        LTORG

05
        SWI     XOS_WriteC
        BVS     ReadLine_Vset
10
        SWI     XOS_ReadC
        BVS     ReadLine_Vset
        BCS     %FT70                   ; ESCAPE

        LDRB    R5, WrchDest            ; does output include VDU ?
        TST     R5, #2
        BNE     %FT30                   ; no, then still buffer

        LDRB    R5, VDUqueueItems       ; is VDU queueing ?
        TEQ     R5, #0
        BNE     %BT05                   ; yes, then just print

30
        TEQ     R0, #127                ; is it DELETE ?
        TEQNE   R0, #8                  ; or backspace?
        BNE     %FT40                   ; no, then skip

        TEQ     R6, #0                  ; yes, then have we any chars ?
        BEQ     %BT10                   ; no, then loop
        SUB     R6, R6, #1              ; go back 1 char
        MOV     R0, #127
        B       %BT05                   ; print DEL and loop

40
        TEQ     R0, #21                 ; is it CTRL-U ?
        BNE     %FT50                   ; no, then skip

        TEQ     R6, #0                  ; yes, then have we any chars ?
        BEQ     %BT10                   ; no, then loop

45
        SWI     XOS_WriteI+127          ; print DELs to start of line
        BVS     ReadLine_Vset
        SUBS    R6, R6, #1
        BNE     %BT45
        B       %BT10                   ; then loop

50
        TEQ     R0, #13                 ; is it CR ?
        TEQNE   R0, #10                 ; or LF ?
        MOVEQ   r0, #13                 ; always store CR if so
        STRB    R0, [R4, R6]            ; store byte in buffer
        BEQ     %FT60                   ; Exit if either

        CMP     R6, R1                  ; is buffer full ?
        MOVCS   R0, #7                  ; if so, beep and loop
        BCS     %BT05

        CMP     R0, R2                  ; is char >= min ?
        CMPCS   R3, R0                  ; and char <= max ?
        ADDCS   R6, R6, #1              ; if so, then inc pointer
        BCS     %FT80
        CMP     R7, #0                  ; no reflection
        BMI     %BT10                   ; of non-entered chars

80      TST     R7, #1:SHL:30
        ANDNE   R0, R7, #&FF            ; echo char -> R0

        B       %BT05                   ; echo character

60      SWI     XOS_NewLine
        BVS     ReadLine_Vset

; insert code here to call NetVec with R0 = &0D

70
        CLRV
EndReadLine
        MOVVC   R0, R4                  ; restore R0
        MOV     R5, #0
        LDRB    R5, [R5, #ESC_Status]
        MOVS    R5, R5, LSL #(32-6)     ; shift esc bit into carry

        MOV     R1, R6                  ; R1 := length
        Pull    "R4-R7, lr"             ; Always claiming vector
        BIC     lr, lr, #V_bit :OR: C_bit
        MOV     r12, pc
        AND     r12, r12, #V_bit :OR: C_bit
        ORRS    pc, lr, r12             ; back with C, V affected.

ReadLine_Vset
        SETV
        B       EndReadLine

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI OS_Control (deprecated): set handlers

SCTRL   Push    "R0-R3, lr"

        TEQP    PC, #SVC_mode+I_bit ; need IRQs off to get consistent state
        MOV     R0, #EventHandler
        MOV     R1, R3
        BL      CallCESWI
        STR     R1, [stack, #3*4]

        MOV     R0, #EscapeHandler
        LDR     R1, [stack, #2*4]
        BL      CallCESWI
        STR     R1, [stack, #2*4]

        MOV     R0, #ErrorHandler
        Pull    "R1, R3"
        BL      CallCESWI
        MOV     R0, R1
        MOV     R1, R3

        Pull    "R2, R3, lr"
        ExitSWIHandler


CallCESWI
        Push    lr
        MOV     r2, #0                  ; readonly
        SWI     XOS_ChangeEnvironment
        Pull    pc

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI OS_SetEnv (deprecated): Environment setting

SSTENV  Push    "R0, R1, lr"
        TEQP    PC, #SVC_mode+I_bit     ; no irqs - want consistent set.
        MOV     R0, #AddressExceptionHandler
        MOV     R1, R7
        SWI     XOS_ChangeEnvironment
        MOV     R7, R1

        MOV     R0, #DataAbortHandler
        MOV     R1, R6
        SWI     XOS_ChangeEnvironment
        MOV     R6, R1

        MOV     R0, #PrefetchAbortHandler
        MOV     R1, R5
        SWI     XOS_ChangeEnvironment
        MOV     R5, R1

        MOV     R0, #UndefinedHandler
        MOV     R1, R4
        SWI     XOS_ChangeEnvironment
        MOV     R4, R1

        MOV     R0, #MemoryLimit
        LDR     R1, [stack, #4]
        SWI     XOS_ChangeEnvironment
        STR     R1, [stack, #4]

        MOV     R0, #ExitHandler
        Pull    "R1"
        BL      CallCESWI
        Push    "R1"

        MOV     R12, #0
        LDR     R2, [R12, #RAMLIMIT]    ; this is read-only
        MOV     R3, #0                  ; never any Brazil-type buffering
                                        ; m2 tools will complain if there is!
        Pull    "R0, R1, lr"
        ExitSWIHandler

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; Change user state SWIs
; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

SINTON  BIC     lr, lr, #I_bit
        ExitSWIHandler

SINTOFF ORR     lr, lr, #I_bit
        ExitSWIHandler

SENTERSWI ORR   lr, lr, #SVC_mode
        ExitSWIHandler

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI OS_BreakPt: user breakpoint - unsuitable for debugging SVC mode code!

SBRKPT ROUT

        ADD     sp, sp, #4              ; discard stacked R11
        MOV     r12, #0
        LDR     r12, [r12, #BrkBf]
        SUB     r14, R14, #4
        STR     r14, [r12, #15*4]       ; PC of the SWI put in.
        TST     r14, #SVC_mode
        BNE     %FT01
        STMIA   r12!, {r0}
        MOV     r0, r12
        LDMFD   sp, {r10-r12}

  [ SASTMhatbroken
        STMIA   r0!,{r1-r12}
        STMIA   r0, {r13_usr,r14_usr}^ ; user mode case done.
        SUB     r0, r0, #12*4
  |
        STMIA   r0, {r1-r12, r13_usr, r14_usr}^ ; user mode case done.
        NOP
  ]

10      LDR     stack, =SVCSTK
        MOV     r12, #BrkAd_ws
        LDMIA   r12, {r12, pc}          ; call breakpoint handler


01      TST     r14, #1                 ; SWI mode?
        TSTNE   r14, #2
        BNE     %FT02                   ; [yes]

        STMIA   r12!, {r0}
        MOV     r0, r12
        LDMFD   sp, {r10-r12}           ; Not banked if IRQ mode
        TEQP    pc, R14                 ; get at registers
        NOP
        STMIA   r0, {r1-r14}
        TEQP    pc, #SVC_mode
        B       %BT10


02      MOV     r14, r12                ; supervisor mode. R14 in buffer dead
        LDMFD   sp!, {r10-r12}
        STMIA   r14, {r0-r14}
        B       %BT10

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI OS_UnusedSWI (deprecated): Set the unused SWI handler

SUNUSED Push    "R1, lr"
        MOV     R1, R0
        MOV     R0, #UnusedSWIHandler
        SWI     XOS_ChangeEnvironment
        MOV     R0, R1
        Pull    "R1, lr"
        ExitSWIHandler

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI OS_SetCallBack: Set callback flag

SSETCALL ROUT

        TEQP    pc, #SVC_mode+I_bit
        MOV     r10, #0
        LDRB    r11, [r10, #CallBack_Flag]
        ORR     r11, r11, #CBack_OldStyle
        STRB    r11, [r10, #CallBack_Flag]
        Pull    "r11"
        Pull    "r10-r12"
        MOVS    pc, lr                  ; Do NOT exit via normal mechanism

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI read mouse information
; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

VecMouse
     MOV   R10, #MouseV
     TEQP  PC, #SVC_mode+I_bit ; no irqs
     Push "lr"
     BL    CallVector
     Pull "lr"
     ExitSWIHandler

 [ :LNOT: DriversInKernel
; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI OS_SerialOp when not in kernel
; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

SerialOp ROUT
        MOV     r10, #SerialV
        Push    lr
        BL      CallVector
        Pull    lr
        BICCC   lr, lr, #C_bit
        ORRCS   lr, lr, #C_bit
        B       SLVK_TestV
 ]

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; Supervisor routines to set default handlers
; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

; Reset Error and Escape handlers

DEFHAN LDR  R1, =GeneralMOSBuffer         ; decent length error buffer
       ADR  R0, ERRORH
       ADR  R2, ESCAPH
       MOV  R3, #0
       MOV  R4, R14
       SWI  XOS_Control

       MOV  r0, #UpCallHandler
       ADR  r1, DefUpcallHandler
       MOV  r2, #0
       SWI  XOS_ChangeEnvironment

       MOV  PC, R4

; Reset Exception, Event, BreakPoint, UnusedSWI, Exit and CallBack handlers

DEFHN2 MOV  R12, R14
       MOV  R0, #0
       MOV  R1, #0
       MOV  R2, #0
       ADR  R3, EVENTH
       SWI  XOS_Control
       LDR  R0, =DUMPER
       ADR  R1, NOCALL
       SWI  XOS_CallBack
       ADRL R0, CLIEXIT
       MOV  R1, #0
       MOV  R2, #0
       ADR  R4, UNDEF
       ADR  R5, ABORTP
       ADRL R6, ABORTD
       ADRL R7, ADDREX
       SWI  XOS_SetEnv
       LDR  R0, =DUMPER
       ADR  R1, DEFBRK
       SWI  XOS_BreakCtrl
       ADRL R0, NoHighSWIHandler
       SWI  XOS_UnusedSWI
       MOV  PC, R12

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; system handlers
; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

DefUpcallHandler
ESCAPH
EVENTH  MOV     pc, lr


NOCALL  MOV     r0, #0                  ; default callback routine
        LDR     r14, [r0, #CallBf]
        LDMIA   r14, {r0-r12, r13_usr, r14_usr}^ ; load user's regs
        NOP
        LDR     r14, [r14, #4*15]
        MOVS    pc, r14


ERRORH ROUT

      [ International
        ADR     R0,KernelMessagesBlock+4
        ADR     R1,ErrorToken
        MOV     R2,#0
        SWI     XMessageTrans_Lookup
        MOVVC   R12,R2
        ADRVS   R12,ErrorText

01
        LDRB    R0,[R12],#1
        CMP     R0,#32
        BLT     %FT99
        CMP     R0,#"%"
        SWINE   XOS_WriteC
        BVS     %FT99
        BNE     %BT01

        LDRB    R0,[R12],#1              ; Found a %
        CMP     R0,#32
        BLT     %FT99

        CMP     R0,#"0"
        LDREQ   R0,=GeneralMOSBuffer+8
        BEQ     %FT10
        CMP     R0,#"1"
        BNE     %BT01

        LDR     R3,=GeneralMOSBuffer+4
        LDR     R0,[R3]
        LDR     R1,=MOSConvertBuffer
        MOV     R2,#12
        SWI     XOS_ConvertHex8

02
        LDRB    R1, [R0], #1
        CMP     R1, #"0"
        BEQ     %BT02
        CMP     R1, #0
        SUBEQ   R0, R0, #1
        SUB     R0, R0, #1

10
        SWI     XOS_Write0
        BVC     %BT01

99
        SWI     XOS_NewLine

        MOV     R0, #0
        STRB    R0, [R0, #ErrorSemaphore]                 ; Enable error translation, in case we got here in the
                                                        ; middle of looking up an error

        B       GOSUPV

ErrorToken      =       "Error:"
ErrorText       =       "Error: %0 (Error Number &%1)",0
        ALIGN
      |

        SWI     OS_WriteS
        =       10,13,"Error:",10,13, 0
        ALIGN
        LDR     r0, =GeneralMOSBuffer+4
        BL      PrintError
        B       GOSUPV
      ]


DEFBRK
      [ International
        TEQP    pc, #0
        MOV     r0, r0
        MOV     r13, #0
        LDR     r13, [r13, #BrkBf]
        LDR     r0, [r13, #15*4]
        LDR     r1, =GeneralMOSBuffer
        MOV     r2, #?GeneralMOSBuffer
        SWI     OS_ConvertHex8

; r0 -> address

        MOV     R4,R0
        ADR     R0,KernelMessagesBlock+4
        ADR     R1,BreakToken
        LDR     R2,=GeneralMOSBuffer+16
        MOV     R3,#256-16
        SWI     XMessageTrans_Lookup
        MOVVC   R0,R2
        ADRVS   R0,BreakText
        SWI     OS_Write0
        SWI     OS_NewLine

      |
        SWI     OS_WriteS
        = "Stopped at break point at &", 0
        ALIGN
        TEQP    pc, #0
        MOV     r0, r0
        MOV     r13, #0
        LDR     r13, [r13, #BrkBf]
        LDR     r0, [r13, #15*4]
        LDR     r1, =GeneralMOSBuffer
        MOV     r2, #?GeneralMOSBuffer
        SWI     OS_ConvertHex8
        SWI     OS_Write0
        SWI     OS_NewLine
      ]

Quit_Code
        SWI     OS_Exit

      [ International

BreakToken      =       "BreakPt:"
BreakText       =       "Stopped at break point at &%0",0
        ALIGN

      ]

PrintError
        MOV    R12, R14
        LDR    R10, [R0], #4
        SWI    XOS_Write0
        BVS    %FT02
      [ :LNOT: International
        SWI    XOS_WriteS
        =     " (Error number &", 0
        BVS    %FT02
      ]
        LDR    R1,=GeneralMOSBuffer
        MOV    R2, #&E0
        MOV    R0, R10
        SWI    XOS_ConvertHex8       ; can't fail!
01      LDRB   R1, [R0], #1
        CMP    R1, #"0"
        BEQ    %BT01
        CMP    R1, #0
        SUBEQ  R0, R0, #1
      [ International                   ; We might not have any stack so ..
        SUB    R11,R0, #1               ; R11 -> Error number
        ADR    R0, KernelMessagesBlock+4
        ADR    R1, PrintErrorString
        MOV    R2,#0                    ; Don't copy message
        SWI    XMessageTrans_Lookup
        ADRVS  R2,PrintErrorString+4    ; If no MessageTrans point at english text.
11
        LDRB   R0,[R2],#1
        CMP    R0,#32
        BLT    %FT13
        CMP    R0,#"%"
        SWINE  XOS_WriteC
        BVS    %FT13
        BNE    %BT11

        LDRB    R0,[R2],#1
        CMP     R0,#32
        BLT     %FT13                   ; Just in case the % is the last character !

        CMP     R0,#"0"                 ; We only know about %0
        BNE     %BT11

12
        LDRB    R0,[R11],#1              ; Print error number.
        CMP     R0,#32
        BLT     %BT11
        SWI     XOS_WriteC
        BVC     %BT12

13
      |
        SUB    R0, R0, #1
        SWI    XOS_Write0
        SWIVC  XOS_WriteI+")"
      ]
        SWIVC  XOS_NewLine
02      MOVS   PC, R12

      [ International
PrintErrorString
        =     "Err: (Error number &%0)", 0
        ALIGN
      ]

        LTORG

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; Exception handling

DumpyTheRegisters  ROUT
        LDR     R1, [R0, -R0]         ; PC when exception happened
        STR     R1, [R0, #(15-8)*4]   ; In the right slot now ...
        TST     R1, #SVC_mode
  [ SASTMhatbroken
        STMEQIA R0!,{R8-R12}
        STMEQIA R0, {R13,R14}^        ; user mode case done.
        SUBEQ   R0, R0, #5*4
  |
        STMEQIA R0, {R8-R14}^         ; user mode case done.
  ]
        BEQ     UNDEF1

        TST     R1, #1                ; SWI mode?
        TSTNE   R1, #2
        BNE     %FT02
        ORR     R1, R1, #I_bit :OR: F_bit
                                 ; keep interrupts off until handlers restored
        TEQP    R1, #0                  ; get at registers
        NOP
        STMIA   R0, {R8-R14}
        TEQP    PC, #SVC_mode :OR: I_bit :OR: F_bit
        AND     R1, R1, #SVC_mode
        EORS    R2, R1, #FIQ_mode       ; Was we in FIQ ? Zero if so
        MOVEQ   R3, #IOC
        STREQB  R2, [R3, #IOCFIQMSK]    ; Blow away all FIQ sources
        B       UNDEF1

02      STMIA   R0, {R8-R14}

; ... and fall into

UNDEF1  LDR     sp, =SVCSTK             ; Flatten superstack

 [ ExceptionsAreErrors
        MOV     R0, #0
        LDR     R0, [R0, #ExceptionDump]
        ADD     R1, R0, #10*4           ; point at dumped R10
        LDMIA   R1, {R10-R12}           ; try and put back user registers
        Push    "R10-R12"               ; for error handler to find on stack
        LDR     R1, [R0, #15*4]
        Push    R1

        LDR     R0, BranchThroughZeroInstruction ; load the B RESET1 instr.
        STR     R0, [R1, -R1]           ; and store it at zero again

        BIC     R14, R14, #ARM_CC_Mask
        LDR     R0, =GeneralMOSBuffer+128 ; so can do deviant sharing !

       [ International
        MOV     r10, #0
        LDRB    r10, [r10, #ErrorSemaphore]
        TEQ     r10, #0                 ; if ok to translate error
        MOVEQ   r10, r14
        BEQ     %FT10
       ]

        LDR     r11, [r14], #4          ; Copy error number
        STR     r11, [r0], #4

01      LDRB    r11, [r14], #1          ; Copy error string
        STRB    r11, [r0], #1
        CMP     r11, #"%"               ; Test for "%" near end of string
        BNE     %BT01
10
        SUB     r1, r0, #1              ; point, ready for conversion

        LDR     R2, =GeneralMOSBuffer+?GeneralMOSBuffer
        SUB     r2, r2, r1              ; amount left in buffer

        MOV     R0, #0
        LDR     R0, [R0, #ExceptionDump]
        LDR     R0, [R0, #15*4]         ; saved PC
        BIC     R0, R0, #ARM_CC_Mask
        SWI     XOS_ConvertHex8

      [ International
        MOV     r4, #0
        LDRB    r4, [r4, #ErrorSemaphore]
        TEQ     r4, #0
        LDRNE   R0, =GeneralMOSBuffer+128
        MOVEQ   R4, R0
        MOVEQ   R0, R10
        BLEQ    TranslateError_UseR4
      |
        LDR     R0, =GeneralMOSBuffer+128
      ]

        TEQP    PC, #IRQ_mode+I_bit
        MOV     R1, #0
        STR     R1, [R1, #IRQsema]
        LDR     SPIRQ, =IRQSTK
        SWI     OS_GenerateError
   |
        Push    R14
        BL      DEFHAN
        BL      DEFHN2
        Pull    R0
        TEQP    PC, #IRQ_mode
        NOP
        LDR     SPIRQ, =IRQSTK
        BIC     R0, R0, #ARM_CC_Mask
        SWI     OS_Write0
        B       UNDEF3
    ]

        LTORG

UNDEF ROUT
        TEQP    pc, #F_bit :OR: I_bit :OR: SVC_mode ; FIQ off too
        STR     R14, [R0, -R0]
        MOV     R14, #0
        LDR     R14, [R14, #ExceptionDump]
        STMIA   R14!, {R0-R7}
        MOV     R0, R14
        BL      DumpyTheRegisters
 [ ExceptionsAreErrors
        MakeErrorBlock UndefinedInstruction
 |
        =       "Undefined instruction at ", 0
        ALIGN
 ]

ABORTP ROUT
        TEQP    pc, #F_bit :OR: I_bit :OR: SVC_mode ; FIQ off too
        STR     R14, [R0, -R0]
        MOV     R14, #0
        LDR     R14, [R14, #ExceptionDump]
        STMIA   R14!, {R0-R7}
        MOV     R0, R14
        BL      DumpyTheRegisters

 [ ExceptionsAreErrors
        MakeErrorBlock InstructionAbort
 |
        =       "Abort on instruction fetch at ", 0
        ALIGN
 ]

ABORTD ROUT
        TEQP    pc, #F_bit :OR: I_bit :OR: SVC_mode ; FIQ off too
        STR     R14, [R0, -R0]
        MOV     R14, #0
        LDR     R14, [R14, #ExceptionDump]
        STMIA   R14!, {R0-R7}
        MOV     R0, R14
        BL      DumpyTheRegisters
 [ ExceptionsAreErrors
        MakeErrorBlock DataAbort
 |
        =       "Abort on data transfer at ", 0
        ALIGN
 ]


ADDREX ROUT
        TEQP    pc, #F_bit :OR: I_bit :OR: SVC_mode ; FIQ off too
        STR     R14, [R0, -R0]
        MOV     R14, #0
        LDR     R14, [R14, #ExceptionDump]
        STMIA   R14!, {R0-R7}
        MOV     R0, R14
        BL      DumpyTheRegisters

 [ ExceptionsAreErrors
        MakeErrorBlock AddressException
 |
        =       "Address exception at ", 0
        ALIGN
 ]


; Can branch through zero in any mode

RESET1 ROUT

        STR     R1, [R0, -R0]
        MOV     R1, #0
        LDR     R1, [R1, #ExceptionDump]
        STMIA   R1, {R0-R15}
        LDR     R0, [R0, -R0]
        STR     R0, [R1, #1*4]
        SWI     XOS_EnterOS

 [ ExceptionsAreErrors
        BL      UNDEF1
        MakeErrorBlock BranchThrough0
 |
        LDR     sp, =SVCSTK
        TEQP    PC, #IRQ_mode
        LDR     SPIRQ, =IRQSTK
        TEQP    PC, #0
        BL      DEFHAN
        BL      DEFHN2
        SWI     OS_WriteS
        =      "Entering Supervisor because of branch through 0", 0
        B       UNDEF2
 ]

BranchThroughZeroInstruction
 [ ProcessorVectors
        LDR     PC, .+ProcVec_Branch0
 |
        B       .+(RESET1-0)
 ]


; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI to call the UpCall vector
; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

DoAnUpCall ROUT

        Push    lr                  ; better have one of these to pull later !
        AND     r10, lr, #&F0000000 ; copy user flags (I_bit clear)
        TEQP    r10, #SVC_mode      ; ints on, stay in SVC mode, flags in psr
        MOV     r10, #UpCallV
        BL      CallVector
        Pull    lr
        BIC     lr, lr, #&F0000000
        MOV     R10, PC, LSR #(32-4)
        ORR     lr, lr, R10, LSL #(32-4)
        ExitSWIHandler

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI OS_ChangeEnvironment: Call the environment change vector
; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

ChangeEnvironment ROUT

        Push    lr
        MOV     R10, #ChangeEnvironmentV
        BL      CallVector
        Pull    lr
        B       SLVK_TestV


; ..... and the default handler .....

AdjustOurSet
        TEQP    PC, #SVC_mode+I_bit
        CMP     R0, #MaxEnvNumber
        BHI     AOS_Silly

  [ False
        CMP     r0, #CallBackHandler
        BLEQ    testcallbackpending
  ]

        ADR     R10, AOS_Table
        ADD     R11, R0, R0, LSL #1   ; number * 3
        ADD     R10, R10, R11, LSL #2 ; point at entry

        MOV     R12, R1
        LDR     R11, [R10]
        CMP     R11, #0
        LDRNE   R1,  [R11]
        CMPNE   R12, #0
        STRNE   R12, [R11]

        MOV     R12, R2
        LDR     R11, [R10, #4]
        CMP     R11, #0
        LDRNE   R2,  [R11]
        CMPNE   R12, #0
        STRNE   R12, [R11]

        MOV     R12, R3
        LDR     R11, [R10, #8]
        CMP     R11, #0
        LDRNE   R3,  [R11]
        CMPNE   R12, #0
        STRNE   R12, [R11]

        Pull    pc,,^

AOS_Silly
        ADR     r0, ErrorBlock_BadEnvNumber
      [ International
        BL      TranslateError
      ]
exit_AOS
        Pull    "lr"
        ORRS    pc, lr, #V_bit
        MakeErrorBlock BadEnvNumber

   [ False

testcallbackpending
        CMP     r1, #0                ; OK if only reading
        CMPEQ   r2, #0
        CMPEQ   r3, #0
        LDRNEB  r10, [r0, #CallBack_Flag-CallBackHandler]
        TSTNE   r10, #CBack_OldStyle
        MOVEQ   pc, r14
  SetBorder r0, r14, 15, 0, 0
        ADR     r0, ErrorBlock_CallbackPending
        B       exit_AOS
        MakeErrorBlock CallbackPending
   ]

AOS_Table
        &  MemLimit     ;  MemoryLimit
        &  0
        &  0

        &  UndHan       ; UndefinedHandler
        &  0
        &  0

        &  PAbHan       ; PrefetchAbortHandler
        &  0
        &  0

        &  DAbHan       ; DatabortHandler
        &  0
        &  0

        &  AdXHan       ; AddressExceptionHandler
        &  0
        &  0

        &  0            ; OtherExceptionHandler
        &  0
        &  0

        &  ErrHan       ; ErrorHandler
        &  ErrHan_ws
        &  ErrBuf

        &  CallAd       ; CallBackHandler
        &  CallAd_ws
        &  CallBf

        &  BrkAd        ; BreakPointHandler
        &  BrkAd_ws
        &  BrkBf

        &  EscHan       ; EscapeHandler
        &  EscHan_ws
        &  0

        &  EvtHan       ; EventHandler
        &  EvtHan_ws
        &  0

        &  SExitA       ; ExitHandler
        &  SExitA_ws
        &  0

        &  HiServ       ; UnusedSWIHandler
        &  HiServ_ws
        &  0

        &  ExceptionDump ; ExceptionDumpArea
        &  0
        &  0

        &  AplWorkSize  ; application space size
        &  0
        &  0

        &  Curr_Active_Object
        &  0
        &  0

        &  UpCallHan
        &  UpCallHan_ws
        &  0

        assert (.-AOS_Table)/12 = MaxEnvNumber

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; SWI OS_ReadDefaultHandler

; In    r0 = environment number

ReadDefaultHandler ROUT

        CMP     r0, #(dhte-defhantab)/12
        MOVHS   r0, #0                  ; return wally value
        ADD     r10, r0, r0, LSL #1     ; *3
        ADD     r10, pc, r10, LSL #2    ; *4 (pc = defhantab-4)
        LDMIB   r10, {r1-r3}            ; gives additional +4
        ExitSWIHandler

defhantab
     & 0                ; wally entry
     & 0
     & 0

     & UNDEF            ; UndefinedHandler
     & 0
     & 0

     & ABORTP           ; PrefetchAbortHandler
     & 0
     & 0

     & ABORTD           ; DataAbortHandler
     & 0
     & 0

     & ADDREX           ; AddressExceptionHandler
     & 0
     & 0

     & 0                ; OtherExceptionHandler
     & 0
     & 0

     & ERRORH           ; ErrorHandler
     & 0
     & GeneralMOSBuffer

     & NOCALL           ; CallBackHandler
     & 0
     & DUMPER

     & DEFBRK           ; BreakPointHandler
     & 0
     & DUMPER

     & ESCAPH           ; EscapeHandler
     & 0
     & GeneralMOSBuffer

     & EVENTH           ; EventHandler
     & 0
     & 0

     & CLIEXIT          ; ExitHandler
     & 0
     & 0

     & NoHighSWIHandler ; UnusedSWIHandler
     & 0
     & 0

     & 0                ; exception dump
     & 0
     & 0

     & 0                ; app space size
     & 0
     & 0

     & 0                ; cao pointer
     & 0
     & 0

     & DefUpcallHandler ; upcall handler
     & 0
     & 0

dhte

; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; In    r0 = sysinfo handle

; Out   r0 = sysinfo for r0in

ReadSysInfo_Code ROUT
        CMP     r0, #1
        BCC     %FT00                   ; r0 = 0
        BEQ     %FT10                   ; r0 = 1
        CMP     r0, #3
        BCC     %FT20                   ; r0 = 2
        BEQ     %FT30                   ; R0 = 3
        CMP     r0, #5
        BCC     %FT40                   ; R0 = 4
        BEQ     %FT50                   ; R0 = 5

        ;       R0 > 5, so illegal value

        ADR     r0, ErrorBlock_BadReadSysInfo
      [ International
        Push    "lr"
        BL      TranslateError
        Pull    "lr"
      ]
        ORR     lr, lr, #V_bit
        ExitSWIHandler

        MakeErrorBlock BadReadSysInfo

; ReadSysInfo(0) - return configured screensize in r0

00
        Push    "r1, r2, lr"
        MOV     r0, #ReadCMOS
        MOV     r1, #ScreenSizeCMOS
        SWI     XOS_Byte
        AND     r0, r2, #&7F            ; top bit is reserved
        MOV     r10, #0
        LDR     r10, [r10, #Page_Size]
        MUL     r0, r10, r0
        BL      MassageScreenSize       ; adjust for min and max or default values
        Pull    "r1, r2, lr"
        ExitSWIHandler

; ReadSysInfo(1) - returns configured mode/wimpmode in r0
;                          configured monitortype in r1
;                          configured sync in r2
;                          (all de-autofied)

10
        Push    "r3-r5, lr"
        BL      Read_Configd_Sync
        MOV     r2, r0
 [ ModeSelectors
        LDR     r1, =VduDriverWorkSpace+CurrentMonitorType      ; read current monitortype
        LDR     r1, [r1]
 |
        BL      Read_Configd_MonitorType
        MOV     r1, r0
 ]
        BL      Read_Configd_Mode
        CMP     r0, #-1                         ; if none of the three are auto, don't bother with translation
        CMPNE   r1, #-1
        CMPNE   r2, #-1
        BNE     %FT15
        BL      TranslateMonitorLeadType        ; issue service or work it out ourselves
        CMP     r0, #-1                         ; if mode auto
        MOVEQ   r0, r3                          ; then replace with default
        CMP     r1, #-1                         ; if monitortype auto
        MOVEQ   r1, r4                          ; then replace with default
        CMP     r2, #-1                         ; if sync auto
        MOVEQ   r2, r5                          ; then replace with default
15
        Pull    "r3-r5, lr"
        ExitSWIHandler

; ReadSysInfo(2)
;
; in:   r0 = 2
;
; out:  r0 = hardware configuration word 0
;               bits 0-7 = special functions chip type
;                               0 => none
;                               1 => IOEB
;               bits 8-15 = I/O control chip type
;                               0 => IOC
;                               1 => IOMD
;               bits 16-23 = memory control chip type
;                               0 => MEMC1/MEMC1a
;                               1 => IOMD
;               bits 24-31 = video control chip type
;                               0 => VIDC1a
;                               1 => VIDC20
;       r1 = hardware configuration word 1
;               bits 0-7 = I/O chip type
;                               0 => absent
;                               1 => 82C710/711 or SMC'665 or similar
;               bits 8-31 reserved (set to 0)
;       r2 = hardware configuration word 2
;               bits 0-7 = LCD controller type
;                               0 => absent
;                               1 => present (type 1) eg A4 portable
;                               2 => present (type 2) eg Stork portable
 [ MorrisSupport
;               bits 8-15 = IOMD variant
;                               0 => IOMD
;                               1 => IOMDL ie ARM7500 (Morris)
;               bits 16-23 = VIDC20 variant
;                               0 => VIDC20
;                               1 => VIDC2L ie ARM7500 (Morris)
;               bits 24-31 reserved (set to 0)
 |
;               bits 8-31 reserved (set to 0)
 ]
;       r3 = word 0 of unique machine ID, or 0 if unavailable
;       r4 = word 1 of unique machine ID, or 0 if unavailable

; Bits in IOSystemType

IOST_COMBOMASK  * 7
IOST_82C710     * 1
IOST_82C711     * 2
IOST_37C665     * 3
IOST_37C669     * 4
IOST_UMC669     * 5
IOST_IOEB       * 8     ; On IOMD systems this really means IOMD.
IOST_LC         * 16
 [ MorrisSupport
IOST_7500       * 32    ;Running on ARM7500 (Morris) so actually IOMDL and VIDC2L
IOST_BATMAN     * 64    ;Stork keyboard/battery controller seems to be present
 ]
20
        MOV     r0, #0
        LDR     r3, [r0, #RawMachineID+0]
        LDR     r4, [r0, #RawMachineID+4]
        MOV     r3, r3, LSR #8                  ; lose first 8 bits
        ORR     r3, r3, r4, LSL #24             ; and put bits 0..7 of r3 into bits 24..31 of r2
        MOV     r4, r4, LSL #8                  ; lose CRC bits
        MOV     r4, r4, LSR #16                 ; and move the rest down to the bottom
        LDRB    r0, [r0, #IOSystemType]

        ANDS    r2, r0, #IOST_LC
        MOVNE   r2, #1                          ; make r2 0 or 1
 [ MorrisSupport
        TST     r0, #IOST_BATMAN
        MOVNE   r2, #2                          ;NE, its a Stork portable
        TST     r0, #IOST_7500
        ORRNE   r2, r2, #&00000100              ;NE, Morris based machine with IOMDL
        ORRNE   r2, r2, #&00010000              ;NE, and VIDC2L
 ]
        ANDS    r1, r0, #IOST_COMBOMASK
        MOVNE   r1, #1                          ; make r1 0 or 1

 [ IO_Type = "IOMD"
   [ VIDC_Type = "VIDC20"
        LDR     r0, =&01010100
   |
        LDR     r0, =&00010100
   ]
 |
        ANDS    r0, r0, #IOST_IOEB
        MOVNE   r0, #1                          ; make r1 0 or 1
   [ VIDC_Type = "VIDC20"
        ORR     r0, r0, #&01000000
   ]
 ]
        ExitSWIHandler

; ReadSysInfo(3)
;
; in:   r0 = 3
;
; out:  r0 = I/O chip base features mask                710     711     665     669     UMC669
;               Bits 0..3   Base IDE type               1       1       1       1       1
;               Bits 4..7   Base FDC type               1       1       1       1       1
;               Bits 8..11  Base parallel type          1       1       1       1       1
;               Bits 12..15 Base 1st serial type        1       1       1       1       1
;               Bits 16..19 Base 2nd serial type        0       1       1       1       1
;               Bits 20..23 Base Config type            1       2       3       4       5
;               Bits 24..31 Reserved                    0       0       0       0       0
;
;       r1 = I/O chip extra features mask               710     711     665     669     UMC669
;               Bits 0..3   IDE extra features          0       0       0       0       0
;               Bits 4..7   FDC extra features          0       0       0       0       0
;               Bits 8..11  parallel extra features     0       0       1       1       1
;               Bits 12..15 1st serial extra features   0       0       1       1       1
;               Bits 16..19 2nd serial extra features   0       0       1       1       1
;               Bits 20..23 config extra features       0       0       0       0       0
;               Bits 24..31 Reserved                    0       0       0       0       0
;
;       r2-r4 undefined (reserved for future expansion)
;

30
        MOV     r0, #0                          ; used as index and as default value
        LDRB    r1, [r0, #IOSystemType]
        ANDS    r1, r1, #IOST_COMBOMASK
        TEQ     r1, #IOST_82C710
        LDREQ   r0, =&00101111
        MOVEQ   r1, #0
        TEQ     r1, #IOST_82C711
        LDREQ   r0, =&00211111
        MOVEQ   r1, #0
        CMP     r1, #IOST_37C665
 [ ReassignedIOMDInterrupts
; If the device numbers have been reassigned, we can't really call the devices compatible.
; Also, we've lost the floppy and hard disc interrupts, so mark as not present.
        LDRHS   r0, =&00022200
 |
        LDRHS   r0, =&00011111
 ]
        ORRHS   r0, r0, r1, LSL #20
        LDRHS   r1, =&00011100
        MOV     r2, #0
        MOV     r3, #0
        MOV     r4, #0
        ExitSWIHandler

; OS_ReadSysInfo 4 (SWI &58)
;
; On entry:       r0 = 4 (reason code)
;
; On exit:        r0 = LSW of Ethernet Network Address (or 0)
;                 r1 = MSW of Ethernet Network Address (or 0)
;
; Use:            Code loaded from the dedicated Network Expansion Card or
;                 from a normal Expansion Card should use the value returned
;                 by this call in preference to a locally provided value.

40
        MOV     r0, #0
        LDRB    r1, [ r0, #RawMachineID ]               ; The family byte
        TEQ     r1, #&81                                ; Is this a custom part?
        BNE     ExitNoEthernetAddress
        LDR     r1, [ r0, #RawMachineID+4 ]             ; Acorn's ID and part#
  [  True
        BIC     r1, r1, #&FF000000                      ; Remove the CRC
        LDR     r0, =&0050A4                            ; Acorn's ID is &005
  | ; Version for no checking of Manufacture's ID
        MOV     r1, r1, LSL #20
        MOV     r1, r1, LSR #20                         ; Remove CRC and ID
        LDR     r0, =&0A4
  ]
        TEQ     r1, r0                                  ; Is this one of our chips?
        BNE     ExitNoEthernetAddress
        MOV     r0, #0
        LDR     r0, [ r0, #RawMachineID ]
        MOV     r0, r0, LSR #8                          ; Lose family byte
        LDR     r1, =&0000A4100000                      ; Base Ethernet address
        ADD     r0, r1, r0                              ; Add Dallas part to base
        [ STB
        TST     r0, #1:SHL:23                           ; Check not overflowed into secondary range
        BNE     ExitNoEthernetAddress
        MOV     r1, r0, LSR #24                         ; Check not overflowed out of Acorn's range
        TEQ     r1, #&A4
        BNE     ExitNoEthernetAddress
        ]
        MOV     r1, #0                                  ; Top 16 bits are zero
        ExitSWIHandler

ExitNoEthernetAddress
        [ :LNOT: STB
        MOV     r0, #0
        MOV     r1, #0
        ExitSWIHandler
        |
        Push    "r2,lr"
        MOV     r1, #Service_MachineAddress             ; See if anyone else can provide it
        BL      Issue_Service
        TEQ     r1, #0
        MOVEQ   r1, r2
        BLNE    GetMachineAddressCMOS
        Pull    "r2,lr"
        ExitSWIHandler
        ]

        [ STB
GetMachineAddressCMOS
; Out:  r0 = lower 4 bytes (or 0)
;       r1 = upper 2 bytes (or 0)
;       EQ => valid, NE => invalid
;
	Entry	"r2,r3", 8				; Preserve these

	ADR	r0, NVRAM_TAG_MACAddress		; Read the MAC address
	MOV	r1, sp
	MOV	r2, #6
	SWI	XNVRAM_Read
	MOVVS	r0, #&ffffffff
	TST	r0, #&80000000				; Check for errors
	BNE	%FT10

	ADR	r0, NVRAM_TAG_MACAddressChecksum	; Read the checksum
	ADD	r1, sp, #6
	MOV	r2, #1
	SWI	NVRAM_Read
	MOVVS	r0, #&ffffffff
	TST	r0, #&80000000				; Check for errors
10
	MOV	r0, #0
	MOV	r1, #0
	BNE	%FT20					; Return zero on error

	LDRB	r3, [sp, #0]				; Get the first byte into checksum
	MOV	r1, r3, ASL #8				; Store into result

	LDRB	r2, [sp, #1]				; Get the next byte
	ADD	r3, r3, r2				; Add to the checksum
	ORR	r1, r1, r2, ASL #0			; Store into the result

	LDRB	r2, [sp, #2]				; Get the next byte
	ADD	r3, r3, r2				; Add to the checksum
	MOV	r0, r2, ASL #24				; Store into the result

	LDRB	r2, [sp, #3]				; Get the next byte
	ADD	r3, r3, r2				; Add to the checksum
	ORR	r0, r0, r2, ASL #16			; Store into the result

	LDRB	r2, [sp, #4]				; Get the next byte
	ADD	r3, r3, r2				; Add to the checksum
	ORR	r0, r0, r2, ASL #8			; Store into the result

	LDRB	r2, [sp, #5]				; Get the next byte
	ADD	r3, r3, r2				; Add to the checksum
	ORR	r0, r0, r2, ASL #0			; Store into the result

	LDRB	r2, [sp, #6]				; Get the checksum
	AND	r3, r3, #&FF
	EOR	r3, r3, #&FF
	TEQ	r2, r3					; Check against the computed value
	MOVNE	r0, #0					; Zero the MAC address on failure
	MOVNE	r1, #0

20
	EXITS

NVRAM_TAG_MACAddress
	= "MACAddress", 0
NVRAM_TAG_MACAddressChecksum
	= "MACAddressChecksum", 0
        ]

; OS_ReadSysInfo 5
;
; On entry:       r0 = 5 (reason code)
;
; On exit:        r0 = LSW of Raw data from Dallas Chip
;                 r1 = MSW of Raw data from Dallas Chip

50
        MOV     r0, #0
        LDR     r1, [r0, #RawMachineID+4]
        LDR     r0, [r0, #RawMachineID+0]
        ExitSWIHandler

        LTORG

        END