# HG changeset patch
# User Tormod Volden <debian.tormod@gmail.com>
# Date 1583613150 -3600
# Node ID d80acb6d104b836ff6189d52bb3e0036bad9dadc
# Parent  359e2f4b5b9191e1706eb4d670f3cd7baa771ee3
os9gen: Fix bitmap check/update where boot sector is non-zero

And on builds where the boot track is zero, most likely for
Dragon, don't check or update the bitmap because the boot
track should be reserved already.

Ideally all this should be a run-time checks of the disk
parameters and not depend on the build target. Later.

diff -r 359e2f4b5b91 -r d80acb6d104b level1/cmds/os9gen.asm
--- a/level1/cmds/os9gen.asm	Sat Mar 07 20:29:51 2020 +0100
+++ b/level1/cmds/os9gen.asm	Sat Mar 07 21:32:30 2020 +0100
@@ -572,11 +572,13 @@
          leax  TrkErr,pcr
          lbcs  WritExit
 
-         ldd   #Bt.Track*256	boot track regD=$2200
+* if boot track is on track zero (i.e. Dragon) skip bitmap check/update
+       IFNE Bt.Track
+         ldd   #Bt.Track*256+Bt.Sec	boot track (regD=$2200 for CoCo)
          ldy   #$0004			four bits
          lbsr  ABMClear		this should test for clear not clear it
          bcc   L0520
-         ldd   #Bt.Track*256	boot track, as it was not clear
+         ldd   #Bt.Track*256+Bt.Sec	read boot track, as it was not clear
          lbsr  Seek2LSN			seek to it
          leax  <u0017,u
          ldy   #$0007
@@ -594,18 +596,22 @@
          lda   $04,x
          cmpa  #$12			also check for NOP
          beq   L0512
-         ldd   #Bt.Track*256+15	boot track, sector 16
-         ldy   #$0003			sectors 16-18
+         ldd   #Bt.Track*256+Bt.Sec+15	boot track, sector 16
+* boldly assume Bt.Sec is nowhere higher than 3 !
+         ldy   #$0003-Bt.Sec			sectors 16-18
          lbsr  ABMClear
          lbcs  WarnUser
 L0512    clra  
          ldb   <lsn0+DD.TKS,u	get number of sectors in D
+        IFNE Bt.Sec
+         subb  #Bt.Sec
+        ENDC
          tfr   d,y
-         ldd   #Bt.Track*256	boot track
+         ldd   #Bt.Track*256+Bt.Sec	boot track
          lbsr  ABMSet
          bra   L0531
-L0520    ldd   #Bt.Track*256+4	boot track
-         ldy   #$000E		sectors 5-18
+L0520    ldd   #Bt.Track*256+Bt.Sec+4	boot track
+         ldy   #$000E-Bt.Sec		sectors 5-18
          lbsr  ABMClear		test rest of track
          lbcs  WarnUser
          bra   L0512
@@ -620,6 +626,7 @@
          lda   <devpath
          os9   I$Write  		write out the bitmap
          lbcs  Bye
+       ENDC
 
 * Code added to write alternate boottrack file
 * BGP - 2003/06/26
@@ -662,7 +669,7 @@
          lbcs  Bye
          os9   I$Close		close path to boot track
          lbsr  GetDest
-         ldd   #Bt.Track*256	boot track
+         ldd   #Bt.Track*256+Bt.Sec	boot track
          lbsr  Seek2LSN
          bra   WrBTrack
 
@@ -688,14 +695,14 @@
          subd  u007B,u
          addd  #$0001
          tfr   d,y
-         ldd   #Bt.Track*256	boot track
+         ldd   #Bt.Track*256+Bt.Sec	boot track
          lbsr  Seek2LSN
          ldx   u007B,u
 
          ELSE
 
 * OS-9 Level One: Write out boot track data
-         ldd   #Bt.Track*256
+         ldd   #Bt.Track*256+Bt.Sec
          lbsr  Seek2LSN
          ldx   #Bt.Start
          ldy   #Bt.Size