# HG changeset patch
# User robertgault
# Date 1316005956 0
# Node ID 538be58c2c2dea8adba39459162fa3e4c23ac224
# Parent  2e7092ed1e104b635d5e08ddcc31c2530bf62518
Support for DD.BIT has been added. The buffer for the bit map is calculated on the fly instead of being hard coded. To prevent parameter corruption by memory expansion, the parameters are copied into the data area.
The above means very large disks can be supported. R.Gault

diff -r 2e7092ed1e10 -r 538be58c2c2d level1/cmds/os9gen.asm
--- a/level1/cmds/os9gen.asm	Wed Sep 14 13:10:54 2011 +0000
+++ b/level1/cmds/os9gen.asm	Wed Sep 14 13:12:36 2011 +0000
@@ -28,12 +28,24 @@
 *
 *  12      2006/05/09  Christopher R. Hawks
 * Weren't clearing -e option, so all os9boot files were extended.
+*
+*  13      2011/09/13  Robert Gault
+* A flexible buffer is now used to hold the FAT map.
+* The boot file name is now copied into the data space for which
+* 160 bytes are reserved. F$Mem trashes parameter space.
+* DD.BIT can now be used to obtain a reasonably sized FAT with large drives.
+* Added error message if not enough room for bit map.
+* Replace sectbuff with bitmbuff for all FAT (DD.MAP) work.
+* Moved common code in ABMClear & ABMSet to subroutine.
 
          nam   OS9Gen
          ttl   OS-9 bootfile generator
 
 * Disassembled 02/07/06 13:11:11 by Disasm v1.6 (C) 1988 by RML
 
+*Needed for stand alone compile
+*LEVEL    equ   2
+
          IFP1
          use   defsfile
          ENDC
@@ -76,6 +88,7 @@
 sngldrv  rmb   1
 bootdev  rmb   32
 lsn0     rmb   26
+btfstr   rmb   160
 u007B    rmb   2
 u007D    rmb   1
 sectbuff rmb   1024
@@ -83,6 +96,8 @@
 u048E    rmb   1
 u048F    rmb   7
 u0496    rmb   7018
+
+bitmbuf	 equ   .
 size     equ   .
 
 name     fcs   /OS9Gen/
@@ -107,6 +122,12 @@
 ErrWrit  fcb   C$LF
          fcc   "Error writing kernel track"
          fcb   C$CR
+MemErr	 fcb   C$LF
+	 fcc   "Not enough memory for bit map"
+	 fcb   C$CR
+TrkErr	 fcb   C$LF
+	 fcc   "Can't read data"
+	 fcb   C$CR
          IFEQ  DOHD
 HDGen    fcb   C$LF
          fcc   "Error - cannot gen to hard disk"
@@ -179,8 +200,8 @@
          leas  >u047E,u		point stack pointer to u047e
          pshs  u
          tfr   y,d			copy pointer to top of our mem in D
-         subd  ,s++			D = Y-u047e
-         subd  #u047E
+         subd  ,s++			D = Y-u047e = 7039
+         subd  #u047E			D = 5889 = $1701 What is it? R.G.
          clrb  
          std   <u0011
          lda   #PDELIM
@@ -215,14 +236,22 @@
          cmpd  #84*256+61	does D = 'T='
          lbne  SoftExit
          leay  1,y			point past =
-         sty   <btfname		save pointer to boottrack filename
+*         sty   <btfname	save pointer to boottrack filename R.G.
          sta   <btflag
+         pshs  x		copy btfname into data space
+         leax  btfstr,u		making room to expand the data space R.G.
+         stx   btfname,u
 * Skip over non-spaces and non-CRs
 SkipNon  lda   ,y+
          cmpa  #C$CR
-         beq   getdev
+         beq   getdev2		we must recover regX
          cmpa  #C$SPAC
-         bne   SkipNon
+         beq   parseopt2	""
+         sta   ,x+
+         bra   SkipNon
+getdev2	 puls  x
+         bra   getdev
+parseopt2 puls x
          bra   parseopt
 remboot  inc   <rflag		remove bootfile reference from LSN0 flag
          bra   parsein
@@ -513,16 +542,27 @@
          lbcs  Bye
          ldd   #$0001
          lbsr  Seek2LSN
-         leax  sectbuff,u
+*        leax  sectbuff,u		R.G. Expand memory to hold buffer
+	 ldd	<lsn0+DD.MAP,u
+	 addd	#bitmbuf+256		expand memory by DD.MAP+256 bytes
+	 os9	F$Mem
+	 leax	MemErr,pcr
+	 lbcs	WritExit
+	 tfr	y,s			relocate stack
+
+*        leax  sectbuff,u
+	 leax	bitmbuf,u
          ldy   <lsn0+DD.MAP,u	get number of bytes in device's bitmap
          lda   <devpath
-         os9   I$Read   
-         lbcs  Bye
-         ldd   #Bt.Track*256	boot track
+         os9   I$Read   	read the FAT into the bitmbuf
+         leax	TrkErr,pcr
+         lbcs  WritExit
+
+         ldd   #Bt.Track*256	boot track regD=$2200
          ldy   #$0004			four bits
-         lbsr  ABMClear
+         lbsr  ABMClear		this should test for clear not clear it
          bcc   L0520
-         ldd   #Bt.Track*256	boot track
+         ldd   #Bt.Track*256	boot track, as it was not clear
          lbsr  Seek2LSN			seek to it
          leax  <u0017,u
          ldy   #$0007
@@ -531,35 +571,37 @@
          lbcs  Bye
          leax  <u0017,u
          ldd   ,x
-         cmpd  #79*256+83		OS ??
-         lbne  WarnUser
+         cmpd  #256*'O+'S		is this an OS-9 boot track
+         lbne  WarnUser			go if not
 *         cmpb  #'O
 *         lbne  WarnUser
 *         cmpb  #'S
 *         lbne  WarnUser
          lda   $04,x
-         cmpa  #$12
+         cmpa  #$12			also check for NOP
          beq   L0512
          ldd   #Bt.Track*256+15	boot track, sector 16
          ldy   #$0003			sectors 16-18
          lbsr  ABMClear
          lbcs  WarnUser
 L0512    clra  
-         ldb   <lsn0+DD.TKS,u	get number of tracks in D
+         ldb   <lsn0+DD.TKS,u	get number of sectors in D
          tfr   d,y
          ldd   #Bt.Track*256	boot track
          lbsr  ABMSet
          bra   L0531
 L0520    ldd   #Bt.Track*256+4	boot track
          ldy   #$000E		sectors 5-18
-         lbsr  ABMClear
+         lbsr  ABMClear		test rest of track
          lbcs  WarnUser
          bra   L0512
 
+* Write altered map back to disk
 L0531
          ldd   #$0001
          lbsr  Seek2LSN
-         leax  sectbuff,u
+*         leax  sectbuff,u
+	 leax	bitmbuf,u
          ldy   <lsn0+DD.MAP,u	get number of bytes in device's bitmap
          lda   <devpath
          os9   I$Write  		write out the bitmap
@@ -675,46 +717,97 @@
 *         leas  $01,s
          rts   
 
-* Bitmap conversion from bit to byte
-* Entry: X = pointer to bitmap
-*        D = bit
-* Exit:  A = bit mask
-*        X = pointer to byte represented by bit D
-L05AA    pshs  y,b
-         lsra  		divide D by 8
-         rorb  
-         lsra  
-         rorb  
-         lsra  
-         rorb  
-         leax  d,x
-         puls  b
-         leay  <BitMask,pcr
-         andb  #$07
-         lda   b,y
-         puls  pc,y
+* Determine bit shift from DD.BIT R.G.
+* Return shift in regY needed for division
+FShift
+	 ldd	lsn0+DD.BIT,u		get sectors per cluster
+         ldy	#-1
+* This finds number of bit shifts for DD.BIT R.G.
+SF1      lsra
+         rorb
+         leay	1,y
+         cmpd	#0
+         bne	SF1
+         rts
+
 
-BitMask  fcb   $80,$40,$20,$10,$08,$04,$02,$01
+* Returns bit in bitmap corresponding to LSN in regA
+* X=bitmap buffer, on exit X points to bitmap byte of our LSN
+L05AA    
+* We need to divide by DD.BITx8 R.G.
+	 pshs y,d
+	 bsr	FShift
+         ldd	,s		recover LSN
+         cmpy	#0
+         beq	GBB3
+* Divide LSN by DD.BIT R.G.
+GBB2     lsra
+         rorb
+         leay	-1,y
+         bne	GBB2
+GBB3     stb	,s		save lsb
+	 andb	#7		Make sure offset within table
+	 stb	1,s		save table mask
+         ldy	#3
+* Now regY is the number of right shifts required for 8 R.G.
+         ldb	,s		recover the lsb
+GBB4     lsra
+         rorb
+         leay	-1,y
+         bne	GBB4
+* Now regD is the byte number in the FAT
+         leax	d,x		point regX at the byte
+	 puls	d
+         leay	<BitTable,pcr	Point to bit table
+         lda 	b,y		Get bit from table
+         puls	pc,y		Restore regY and return
+
+BitTable    fcb   $80,$40,$20,$10,$08,$04,$02,$01	Bitmap bit table
+
+* Common routine used by ABMSet & ABMClear  R.G.
+Initcalc bsr   AbsLSN		convert A:B to LSN
+*         leax  sectbuff,u	R.G.
+	 leax	bitmbuf,u
+         bsr   L05AA		getbitmapbit
+         pshs	d,y
+	 bsr	FShift		R.G. code to include DD.BIT
+	 cmpy	#0
+	 bne	ABM2
+	 puls	d,y
+	 bra	ABM3
+ABM2	 ldd	2,s		recover regY sector count
+* Divide sector count by DD.BIT
+ABMlp    lsra
+	 rorb
+	 leay	-1,y
+	 bne	ABMlp
+	 cmpd	#0
+	 bne	ABMnz
+	 incb			should never be zero bits
+ABMnz	 tfr	d,y		regY has been divided by DD.BIT
+	 ldd	,s		recover content
+	 leas	4,s		clean stack
+	 rts
+ABM3	 equ	*
 
 * Clear bits in the allocation bitmap
 * Entry: A = Track, B = Sector, Y = number of bits to clear
 ABMClear pshs  x,y,b,a
-         bsr   AbsLSN		convert A:B to LSN
-         leax  sectbuff,u
-         bsr   L05AA
-         sta   ,-s
-         bmi   L05EA
+	 bsr   Initcalc
+* Back to older code
+         sta   ,-s		save map bit
+         bmi   L05EA		go if bit #7
 L05D3    lda   ,x			get byte in bitmap
          sta   u007D,u
-L05D9    anda  ,s			and with byte on stack
-         bne   L0616
-         leay  -1,y
+L05D9    anda  ,s			test byte on stack
+         bne   L0616		go if already set
+         leay  -1,y		next bit to test
          beq   L0612
          lda   u007D,u
          lsr   ,s
          bcc   L05D9
          leax  $01,x
-L05EA    lda   #$FF
+L05EA    lda   #$FF		
          sta   ,s
          bra   L05FA
 L05F0    lda   ,x
@@ -743,9 +836,8 @@
 * Set bits in the allocation bitmap
 * Entry: A = Track, B = Sector, Y = number of bits to set
 ABMSet   pshs  y,x,b,a
-         lbsr  AbsLSN
-         leax  sectbuff,u
-         bsr   L05AA
+	 lbsr   Initcalc
+* Back to old code
          sta   ,-s
          bmi   L063A
          lda   ,x