Increase maximum supported buffer size to 4k

LowFSI: Max_BuffSize define changed.
FileSwBody: Module workspace claim changed to claim Max_BuffSize in addition to the workspace required, so that all the variables in the workspace remain within ADR range.
OSFind: Vetting of acceptable buffer sizes now produced with a WHILE/WEND loop.
StreamBits: Changed to use 'free' flag rather then comparing with 'Nowt'.
MkClean/MkRom: Throwback enabled.

Tested in IOMD ROM, workspace manually inspected as OK.

Version 2.82. Tagged as 'FileSwitch-2_82'

MkClean,fd7

@@ -14,5 +14,4 @@
 |
 Dir <Obey$Dir>
 amu_machine clean
-
-ifthere Run:stripdepnd then stripdepnd <Obey$Dir>.Makefile
+stripdepnd

MkRom,fd7

@@ -13,4 +13,4 @@
 | limitations under the License.
 |
 Dir <Obey$Dir>
-amu_machine rom
+amu_machine rom THROWBACK=-throwback

VersionASM

@@ -11,13 +11,13 @@
                         GBLS    Module_HelpVersion
                         GBLS    Module_ComponentName
                         GBLS    Module_ComponentPath
-Module_MajorVersion     SETS    "2.81"
-Module_Version          SETA    281
+Module_MajorVersion     SETS    "2.82"
+Module_Version          SETA    282
 Module_MinorVersion     SETS    ""
-Module_Date             SETS    "13 Jan 2013"
-Module_ApplicationDate  SETS    "13-Jan-13"
+Module_Date             SETS    "11 Mar 2013"
+Module_ApplicationDate  SETS    "11-Mar-13"
 Module_ComponentName    SETS    "FileSwitch"
 Module_ComponentPath    SETS    "castle/RiscOS/Sources/FileSys/FileSwitch"
-Module_FullVersion      SETS    "2.81"
-Module_HelpVersion      SETS    "2.81 (13 Jan 2013)"
+Module_FullVersion      SETS    "2.82"
+Module_HelpVersion      SETS    "2.82 (11 Mar 2013)"
                         END

VersionNum

-/* (2.81)
+/* (2.82)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  * Last processed by srccommit version: 1.1.
  *
  */
-#define Module_MajorVersion_CMHG        2.81
+#define Module_MajorVersion_CMHG        2.82
 #define Module_MinorVersion_CMHG        
-#define Module_Date_CMHG                13 Jan 2013
+#define Module_Date_CMHG                11 Mar 2013
 
-#define Module_MajorVersion             "2.81"
-#define Module_Version                  281
+#define Module_MajorVersion             "2.82"
+#define Module_Version                  282
 #define Module_MinorVersion             ""
-#define Module_Date                     "13 Jan 2013"
+#define Module_Date                     "11 Mar 2013"
 
-#define Module_ApplicationDate          "13-Jan-13"
+#define Module_ApplicationDate          "11-Mar-13"
 
 #define Module_ComponentName            "FileSwitch"
 #define Module_ComponentPath            "castle/RiscOS/Sources/FileSys/FileSwitch"
 
-#define Module_FullVersion              "2.81"
-#define Module_HelpVersion              "2.81 (13 Jan 2013)"
-#define Module_LibraryVersionInfo       "2:81"
+#define Module_FullVersion              "2.82"
+#define Module_HelpVersion              "2.82 (11 Mar 2013)"
+#define Module_LibraryVersionInfo       "2:82"

hdr/LowFSI

@@ -85,18 +85,13 @@ $label._FSInfoBlock
 
 ; The variable Max_BuffSize determines the maximum permitted value for the
 ;  "natural block size" returned by a Filing System to FileSwitch when
-;  FSEntry_Open is called.
+;  FSEntry_Open is called. The value must be a power of 2.
 ;
 ; In versions of FileSwitch prior to 2.28, this was hard-coded as 1024.
-;
-; The value must be a power of 2, and is set to 2048 in 2.28. This is of
-;  considerable benefit to CDFS, since the sector size on CD-ROMs is
-;  2048 bytes.
-;
-; If any value other than 1024 or 2048 is chosen, code in s.OSFind will also
-;  need to be changed (search for Max_BuffSize and it's obvious).
+; From FileSwitch 2.28 it is 2048, which is of considerable benefit to CDFS.
+; From FileSwitch 2.82 it is 4096, for Advanced Format '4Kn' harddiscs.
 
-Max_BuffSize   *   2048
+Max_BuffSize   *   4096
 
 
 ; Offsets from start of FS information block in a FS module

s/FileSwBody

@@ -395,11 +395,12 @@ streamtable     #       streamtable_size
  ! 0, "Change ShowHeap streamtable to &":CC:(:STR:(:INDEX: streamtable))
  ]
 
- [ sparebuffer
-SpareBufferArea #       Max_BuffSize + 4*4
- ASSERT bcb_size = 4*4
-SpareBuffer     #       4
- ]
+EnvStringAddr   #       4       ; Only needed when we're not bound to kernel
+EnvTimeAddr     #       4
+SVCSTK          #       4
+SysHeapStart    #       4
+
+ptr_DomainId    #       4       ; Pointer to kernel's DomainId var
 
 ; Byte size global variables
 
@@ -409,15 +410,12 @@ copy_n_upcalls  #       1       ; Reference count on UpCallV
  [ StrongARM
 codeflag	#	1	; 0 if data being loaded, 1 if code
  ]
-
-           AlignSpace
-EnvStringAddr   #       4       ; Only needed when we're not bound to kernel
-EnvTimeAddr     #       4
-SVCSTK          #       4
-SysHeapStart    #       4
-
-ptr_DomainId    #       4       ; Pointer to kernel's DomainId var
-
+                #       1       ; Pad
+ [ sparebuffer
+SpareBufferFree #       1       ; Flag, non zero denotes free for use
+           AlignSpace   16
+SpareBufferArea #       0       ; Must be last, it's Max_BuffSize long
+ ]
 
 ; No need to align end of global workspace; saves alloc when rounded!
 
@@ -767,7 +765,13 @@ FileSwitch_Init Entry "r7"
         DLINE "Hard Init"
  ]
         MOV     r0, #ModHandReason_Claim
+ [ sparebuffer
+        LDR     r3, =FileSwitchWorkspace_size + Max_BuffSize + (4*4)
+        ASSERT  bcb_size = (4*4)
+        ASSERT  :INDEX:SpareBufferArea = FileSwitchWorkspace_size
+ |
         LDR     r3, =FileSwitchWorkspace_size
+ ]
         SWI     XOS_Module
         EXIT    VS
 
@@ -842,11 +846,12 @@ fsw_varcount SETA fsw_varcount + 4
         BNE     %BT10
 
  [ sparebuffer
-        ADR     r14, SpareBufferArea    ; Nobody owns this yet
-        STR     r14, SpareBuffer
-        MOV     r14, #Max_BuffSize      ; bufmask for this buffer is permanent
-        SUB     r14, r14, #1
-        STR     r14, SpareBufferArea + :INDEX: bcb_actualsize
+        MVN     r14, #0                 ; Nobody owns this yet
+        STRB    r14, SpareBufferFree
+        ADR     r14, SpareBufferArea
+        MOV     r0, #Max_BuffSize       ; bufmask for this buffer is permanent
+        SUB     r0, r0, #1
+        STR     r0, [r14, #:INDEX:bcb_actualsize]
  ]
  [ debuginittime
         Pull    "r1"

s/OSFind

@@ -663,14 +663,12 @@ StuffTheStreamInfo Entry "r1"
         ORREQ   r14, r14, #scb_unbuffered
         STR     r14, scb_status ; Store access mode, buffer state, EOF clear
 
- [ Max_BuffSize >= 2048
-        TEQNE   r2, #2048       ; vital for efficient CDFS access
- ]
-        TEQNE   r2, #1024       ; Limited range of sensible buffer sizes
-        TEQNE   r2, #512
-        TEQNE   r2, #256
-        TEQNE   r2, #128
-        TEQNE   r2, #64         ; Below this seems senseless !
+        GBLA    buffsize
+buffsize SETA   Max_BuffSize
+        WHILE   buffsize >= 64  ; Below this seems senseless !
+        TEQNE   r2, #buffsize   ; Range of sensible buffer sizes
+buffsize SETA   buffsize / 2
+        WEND
         BNE     %FA85           ; Deallocate stream if failed
 
 ; Store the path strings for this object

s/StreamBits

@@ -385,10 +385,11 @@ ClaimBuffer Entry "r0-r3, bufmask"
         EXIT    NE
 
  [ sparebuffer
-        LDR     bcb, SpareBuffer        ; Try our spare buffer
-        TEQ     bcb, #Nowt
-        MOVNE   r14, #Nowt
-        STRNE   r14, SpareBuffer        ; Claim it
+        LDRB    r14, SpareBufferFree    ; Try our spare buffer
+        TEQ     r14, #0
+        MOVNE   r14, #0
+        STRNEB  r14, SpareBufferFree    ; Claim it
+        ADRNE   bcb, SpareBufferArea
  [ debugstream
  BEQ %FT00
  DREG bcb,"Using SpareBuffer:"
@@ -538,7 +539,8 @@ DeallocateBuffer EntryS "r2"
  [ sparebuffer
         ADR     r14, SpareBufferArea    ; Freeing our spare ?
         CMP     r14, r2                 ; VClear
-        STREQ   r14, SpareBuffer
+        MVNEQ   r14, #0
+        STREQB  r14, SpareBufferFree
         BLNE    SFreeArea
  |
         BL      SFreeArea