Teach FileCore_LayoutStructure and Service_IdentifyDisc how to do 1 zone fixed discs.

From the change logs it was last fixed sometime around FileCore 2.50 era, but has been long broken.
The boot block was in the right place, but was overwritten by the root directory, and the wrong size entry was claimed in the map, amongst other errors.
Free'd up R6 in LayoutFreeSpaceMap to avoid having to keep reevaluating the number of zones - makes it a bit more readable. Corrected inaccurate comments. Checked the code paths for new map with and without boot block, with and without long filenames.
Test app 'Make1Zone' generates a small disc image which can be inspected in a hex editor for correctness.
In the identify code, be more strict about looking for a boot block only on fixed discs since they cannot occur on floppies (saves time, wasn't necessarily wrong).
The concept of a boot block at &C00 only works when 2 copies of the map can be fitted underneath that address, for future 2k and 4k sector sizes these do not fit and it is likely that 1 zone fixed discs are forbidden (a drive with 4k sectors would typically be > 512GB and 1 zone would be ~32MB so spilling into a second zone would waste < 0.01%).
Other minor changes:
* Free command now groups the 'K' with 'bytes' to match OS_ConvertFileSize.
* FileCore20 debug didn't assemble.
* FileCore33 beefed up comments.
* GenSWIs debug didn't assemble.
Tested with a special cut of RAMFS manually loading various 1 zone images into its dynamic area and checking they mount, have a sensible *MAP and *FREE result, can be written to, and don't have broken directories.

Version 3.46. Tagged as 'FileCore-3_46'

Resources/Germany/Messages

@@ -24,8 +24,8 @@ DC1:| hat einen Defekt an Position %0.|M|J
 AreYouSure:Sind Sie sicher (J/N)?
 FC0:Bytes frei    &%0 = %1|M|J
 FC1:Bytes benutzt &%0 = %1|M|J
-FCK0:Bytes frei &%0 = %1K bytes|M|J
-FCK1:Bytes benutzt &%0 = %1K bytes|M|J
+FCK0:Bytes frei &%0 = %1 Kbytes|M|J
+FCK1:Bytes benutzt &%0 = %1 Kbytes|M|J
 MC0:(   Start,  Länge) altes Organisationsformat, alte Verzeichnisse|M|J
 MC1:(   Start,  Länge) altes Organisationsformat, neue Verzeichnisse|M|J
 MC2:(   Start,  Länge) neues Organisationsformat, alte Verzeichnisse|M|J

Resources/UK/Messages

@@ -28,8 +28,8 @@ DC1:| has defect at offset %0|M|J
 AreYouSure:Are you sure (Y/N) ?
 FC0:Bytes free &%0 = %1|M|J
 FC1:Bytes used &%0 = %1|M|J
-FCK0:Bytes free &%0 = %1K bytes|M|J
-FCK1:Bytes used &%0 = %1K bytes|M|J
+FCK0:Bytes free &%0 = %1 Kbytes|M|J
+FCK1:Bytes used &%0 = %1 Kbytes|M|J
 MC0:(   start,  length) old map, old directories|M|J
 MC1:(   start,  length) old map, new directories|M|J
 MC2:(   start,  length) new map, old directories|M|J

VersionASM

@@ -11,13 +11,13 @@
                         GBLS    Module_HelpVersion
                         GBLS    Module_ComponentName
                         GBLS    Module_ComponentPath
-Module_MajorVersion     SETS    "3.45"
-Module_Version          SETA    345
+Module_MajorVersion     SETS    "3.46"
+Module_Version          SETA    346
 Module_MinorVersion     SETS    ""
-Module_Date             SETS    "14 Oct 2011"
-Module_ApplicationDate  SETS    "14-Oct-11"
+Module_Date             SETS    "25 Nov 2011"
+Module_ApplicationDate  SETS    "25-Nov-11"
 Module_ComponentName    SETS    "FileCore"
 Module_ComponentPath    SETS    "castle/RiscOS/Sources/FileSys/FileCore"
-Module_FullVersion      SETS    "3.45"
-Module_HelpVersion      SETS    "3.45 (14 Oct 2011)"
+Module_FullVersion      SETS    "3.46"
+Module_HelpVersion      SETS    "3.46 (25 Nov 2011)"
                         END

VersionNum

-/* (3.45)
+/* (3.46)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  * Last processed by srccommit version: 1.1.
  *
  */
-#define Module_MajorVersion_CMHG        3.45
+#define Module_MajorVersion_CMHG        3.46
 #define Module_MinorVersion_CMHG        
-#define Module_Date_CMHG                14 Oct 2011
+#define Module_Date_CMHG                25 Nov 2011
 
-#define Module_MajorVersion             "3.45"
-#define Module_Version                  345
+#define Module_MajorVersion             "3.46"
+#define Module_Version                  346
 #define Module_MinorVersion             ""
-#define Module_Date                     "14 Oct 2011"
+#define Module_Date                     "25 Nov 2011"
 
-#define Module_ApplicationDate          "14-Oct-11"
+#define Module_ApplicationDate          "25-Nov-11"
 
 #define Module_ComponentName            "FileCore"
 #define Module_ComponentPath            "castle/RiscOS/Sources/FileSys/FileCore"
 
-#define Module_FullVersion              "3.45"
-#define Module_HelpVersion              "3.45 (14 Oct 2011)"
-#define Module_LibraryVersionInfo       "3:45"
+#define Module_FullVersion              "3.46"
+#define Module_HelpVersion              "3.46 (25 Nov 2011)"
+#define Module_LibraryVersionInfo       "3:46"

s/Defns

@@ -277,20 +277,16 @@ Check1          # 1     ;checksum on sector 1
 
 ; New map
 
+ZoneDiscRecSz   * 60    ;reserve additional bytes
+Zone0Bits       * ZoneDiscRecSz*8
+                ASSERT ZoneDiscRecSz >= SzDiscRec
+
                 ^ 0
 ZoneCheck       # 1
 FreeLink        # 2     ;15 bit free space start link
 CrossCheck      # 1     ;EORing this byte for all zones should yield &FF
-
-DummyLenBit     bit 31  ;always set
-
-ZoneDiscRecSz   * 60    ;reserve additional bytes
-                ASSERT ZoneDiscRecSz>=SzDiscRec
-
 ZoneHead        # ZoneDiscRecSz
 
-Zone0Bits       * ZoneDiscRecSz*8
-
 ;zones are followed in RAM by table of one byte of flags per zone
 
 ZoneValid       bit 0
@@ -479,7 +475,7 @@ BigDirTailSize          * -@
 
 BigDirMaxNameLen        * 255   ; maximum name length is 255 chars
 
-BigDirMinSize           * 2048
+BigDirMinSize           * &800
 BigDirMaxSize           * 4*1024*1024
 
  ]

s/FileCore20

@@ -125,7 +125,7 @@ WhatDiscCommon
         BL      SetVOnR0
  [ Debug4 :LOR: DebugL
 
-        LDR     lr, [r3, #RootDir]
+        LDR     lr, [r3, #DiscRecord_Root]
         DREG    lr, "RootDir on Exit WhatDisc is: "
 
         DREG    R1, "<WhatDisc(Drv=",cc

s/FileCore33

@@ -659,13 +659,13 @@ MapDiscAdd ROUT
  |
         Push    "R0,LR"
  ]
-        MOV     R0, #8
-        MOV     R0, R0, LSL R7
+        MOV     R0, #8                  ; bits in a byte
+        MOV     R0, R0, LSL R7          ; bits in a zone
         LDR     LR, [R5,#DiscRecord_ZoneSpare-2]
-        SUB     R0, R0, LR, LSR #16     ;bits used in a zone
-        MOVS    LR, R9, LSR #1          ;zone containing map
+        SUB     R0, R0, LR, LSR #16     ; bits used in a zone
+        MOVS    LR, R9, LSR #1          ; zone containing map
         MULS    R2, R0, LR
-        SUBNE   R2, R2, #Zone0Bits
+        SUBNE   R2, R2, #Zone0Bits      ; adjust for zone 0 disc record
         LDRB    R0, [R5,#DiscRecord_Log2bpmb]
         LDR     LR, [R5,#DiscRecord_Root]
         AND     LR, LR,#DiscBits
@@ -962,7 +962,7 @@ MapPtrToDiscAdd ROUT
         LDRB    LR, [R10,#ZoneHead+DiscRecord_Log2bpmb]
 
 ; when we get here, we have the disc address in units map bits.  Just shift
-; left by lg2bpmb, and if bigdisc also adjust for the sector size
+; left by log2bpmb, and if bigdisc also adjust for the sector size
 
  [ BigDisc
         LDRB    R10,[R10,#ZoneHead+DiscRecord_Log2SectorSize]   ; log2 sector size
@@ -1028,7 +1028,7 @@ MapPtrToZoneBase ROUT
         LDRB    LR, [R10,#ZoneHead+DiscRecord_Log2bpmb]
 
 ; when we get here, we have the disc address in units map bits.  Just shift
-; left by lg2bpmb, and if bigdisc also adjust for the sector size
+; left by log2bpmb, and if bigdisc also adjust for the sector size
 
         LDRB    R10,[R10,#ZoneHead+DiscRecord_Log2SectorSize]   ; log2 sector size
         SUBS    LR,LR,R10               ; get overall shift

s/GenSWIs

@@ -461,6 +461,11 @@ DO64_R2Offset * 4
         ORR     R2,R1,R2,LSL #(32-3)    ; sector addr
         EOR     R2, R2, #bit31          ; Convert to internal drive numbering
 
+ [ DebugL :LOR: Debug2D
+        DREG    R2, "Original address : "
+        DREG    R3, "Log2SectorSize : "
+ ]
+
         Pull    "R1,R3"
  [ DebugL :LOR: Debug2D
         DREG    r1, "DriveOp(",cc
@@ -473,10 +478,6 @@ DO64_R2Offset * 4
 ;       LDR     LR,DiscOp_ByteAddr      ; get end addr
         LDRB    R5,[R5,#DiscRecord_Log2SectorSize]
         LDR     R1,[SP, #DO64_R2Offset]
- [ DebugL :LOR: Debug2D
-        DREG    R2, "Original address : "
-        DREG    R3, "Log2SectorSize : "
- ]
         BIC     R2,R2,#DiscBits
         RSB     LR,R5,#32
         MOV     LR,R2,LSR LR

s/Identify

@@ -18,7 +18,7 @@
 
 ; change log:
 
-; 15 May 1997: SBP: Changed SanityCheckEDiscRecord to support LinkBits up to 16.
+; 15 May 1997: SBP: Changed SanityCheckEDiscRecord to support idlen up to 16.
 
 
 ; ============
@@ -153,7 +153,7 @@ IdentifyFileCoreDisc ROUT
         MOV     R12, R13
         DREG    R12, ","
  ]
-       MOV     r12, r8
+        MOV     r12, r8
  [ DebugL
         DREG    r8, "r8 in is "
         DREG    r12, "Meaning ws is "
@@ -755,7 +755,7 @@ SanityCheckEDiscRecord ROUT
         CMP     r0, #0
  [ DebugL
         BNE     %FT01
-        DLINE   "Failed on LinkBits = 0"
+        DLINE   "Failed on idlen = 0"
 01
  ]
         BEQ     %FT85
@@ -788,7 +788,7 @@ SanityCheckEDiscRecord ROUT
         MOVS    r14, r1, LSR r0
  [ DebugL
         BEQ     %FT01
-        DLINE   "Failed on 2^LinkBits < Max Total objects"
+        DLINE   "Failed on 2^idlen < Max Total objects"
 01
  ]
         BNE     %FT85                   ; If shifting right by idlen leaves a non-0
@@ -800,7 +800,7 @@ SanityCheckEDiscRecord ROUT
         LDRB    r2, [sp, #DiscRecord_IdLen]
 
  [ BigMaps
-        ; if BigMaps then idlen can be more than MaxFreeLink, so test agains
+        ; if BigMaps then idlen can be more than MaxFreeLink, so test against
         ; MaxFreeLink (we're being paranoid here, since maximum sector is 1024
         ; bytes, needing 13 link bits)
 
@@ -851,7 +851,7 @@ SanityCheckEDiscRecord ROUT
         LDRB    r1, [sp, #DiscRecord_NZones]
  ]
         MOV     r1, r1, ASL #1
-        LDRB    r0, [sp, #DiscRecord_BigMap_ShareSize]    ; factor in sharesize
+        LDRB    r0, [sp, #DiscRecord_BigMap_ShareSize]  ; factor in sharesize
         MOV     lr, #1
         ADD     r1, r1, lr, LSL r0
         SUB     r1, r1, #1
@@ -861,8 +861,8 @@ SanityCheckEDiscRecord ROUT
         LDR     r0, [sp, #DiscRecord_Root]
         TEQ     r0, r1
  |
-        ; Check RootDir is sensible:
-        ; Must be &000002nn where nn=2*Zones+1
+        ; Check RootDir is sensible: must be &000002nn
+        ; where nn = (2*Zones) + 1
  [ BigMaps
         LDRB    r1, [sp, #DiscRecord_NZones]
         LDRB    r0, [sp, #DiscRecord_BigMap_NZones2]    ; r0 due to be corrupted
@@ -883,20 +883,28 @@ SanityCheckEDiscRecord ROUT
  ]
         BEQ     %FT10
 
-        ; or, if Zones == 1, then &000002nn where nn = (&e00 + 1<<DiscRecord_Log2SectorSize - 1)>>DiscRecord_Log2SectorSize + 1
-        LDRB    r1, [sp, #DiscRecord_NZones]
-        TEQ     r1, #1
+        ; or, another last ditch attempt if Zones=1 and density=0
+        ; where nn = ((bootblock + bootblocksize + (1<<DiscRecord_Log2SectorSize) - 1) >> DiscRecord_Log2SectorSize) + 1
  [ BigMaps
-        LDREQB  r1, [sp, #DiscRecord_BigMap_NZones2]
-        TEQEQ   r1, #0          ; have to also check that Zones2 is 0
+        LDRB    r1, [sp, #DiscRecord_NZones]
+        LDRB    r14, [sp, #DiscRecord_BigMap_NZones2]
+        ORR     r1, r1, r14, LSL #8
+ |
+        LDRB    r1, [sp, #DiscRecord_NZones]
  ]
+        LDRB    r14, [sp, #DiscRecord_Density]
+        ORR     r14, r1, r14, LSL #16
+        TEQ     r14, #1                                 ; EQ iff density=0 zones=1
         BNE     %FT85
 
+ [ DebugL
+        DLINE   "Might be a 1 zone fixed disc"
+ ]
         MOV     r14, #1
         LDRB    r1, [sp, #DiscRecord_Log2SectorSize]
         MOV     r14, r14, ASL r1
-        ADD     r14, r14, #DefectListDiscAdd + SzDefectList
         SUB     r14, r14, #1
+        ADD     r14, r14, #DefectListDiscAdd + SzDefectList
         MOV     r14, r14, LSR r1
         ADD     r14, r14, #1
         ORR     r14, r14, #&200
@@ -1084,11 +1092,11 @@ SanityCheckNewMap ROUT
         LDRB    r9, [r5, #DiscRecord_NZones]
         LDRB    r7, [r5, #DiscRecord_BigMap_NZones2]
         ADD     r9, r9, r7, LSL #8
-        LDRB    r7, [r5, #DiscRecord_Log2SectorSize]
  |
-        LDRB    r7, [r5, #DiscRecord_Log2SectorSize]
         LDRB    r9, [r5, #DiscRecord_NZones]
  ]
+        LDRB    r7, [r5, #DiscRecord_Log2SectorSize]
+
         BL      MapDiscAdd
         MOV     r7, r2
 
@@ -1188,10 +1196,12 @@ SanityCheckNewMap ROUT
         BNE     %FT85
 
         ; Try on the second map copy
-        LDRB    r8, [r5, #DiscRecord_NZones]
  [ BigMaps
+        LDRB    r8, [r5, #DiscRecord_NZones]
         LDRB    r0, [r5, #DiscRecord_BigMap_NZones2]
         ADD     r8, r8, r0, LSL #8
+ |
+        LDRB    r8, [r5, #DiscRecord_NZones]
  ]
         LDRB    r0, [r5, #DiscRecord_Log2SectorSize]
  [ BigDisc