enhance autorun.sys.

1 files changed, 85 insertions, 32 deletions

diff --git a/autorun.s b/autorun.s
index c7bbac0..dc0f5dd 100644
--- a/autorun.s
+++ b/autorun.s
@@ -1,3 +1,13 @@
+; autorun.s - display an intro screen and a menu from which the user
+; can launch dla.xex or dla2csv.xex, or exit to DOS.
+
+; I was *going* to write this in C, using cc65's exec()... but it
+; turns out to only be implemented on XDOS, which is a rather uncommon
+; DOS. MyDOS has XIO 40 (execute binary file), which is a lot easier
+; to deal with in asm. Other DOSes might support XIO 40, and/or this
+; might support other DOSes someday... Or I could write my own xex
+; file loader (rather not).
+
  .include "atari.inc"
  .include "xex.inc"
 
@@ -8,19 +18,24 @@ old_sdlstl: .res 1
 old_sdlsth: .res 1
 old_color2: .res 1
 old_color1: .res 1
+keycode:    .res 1
 
  .code
 
+ ; this doesn't have to be aligned on a 4K boundary, but it should
+ ; be aligned to 1K.
 loadaddr = $3000
 
  xex_org loadaddr
 screendata:
- .incbin "about.dat"
+ .incbin "about.dat" ; generated from ABOUT.txt, by text2screen.pl
 
+ ; 960 bytes is exactly one GR.0 screen (40x24)
  .if ((* - screendata) <> 960)
    .error .sprintf("%c*** about.dat is %d bytes (should be 960)", 10, * - screendata)
  .endif
 
+ ; bog-standard GRAPHICS 0 display list (except the LMS address)
 dlist:
  .byte DL_BLK8, DL_BLK8, DL_BLK8
  .byte DL_CHR40x8x1 | DL_LMS
@@ -31,14 +46,22 @@ dlist:
  .byte DL_JVB
  .word dlist
 
+ .if ((* / 1024) <> (screendata / 1024))
+  .error .sprintf("%c*** screendata and dlist cross a 1K boundary!", 10)
+ .endif
+
+ .include "io.s"
+ .include "printint.s"
+
 main:
  ; fix things so the Reset key doesn't do a coldstart, see
  ; BOOT? and COLDST in Mapping.
- lda #0
- sta COLDST
- lda #1
- sta BOOTQ
+ ldx #0
+ stx COLDST
+ inx
+ stx BOOTQ
 
+ ; save the OS's colors and display list.
  lda SDLSTL
  sta old_sdlstl
  lda SDLSTH
@@ -48,6 +71,7 @@ main:
  lda COLOR2
  sta old_color2
 
+ ; use our own colors and display list (displays our message).
  lda #$90
  sta COLOR2
  lda #$0e
@@ -57,14 +81,19 @@ main:
  lda #>dlist
  sta SDLSTH
 
-loop:
- ldx CH
- cpx #$ff
- beq loop
+ ; wait for a keypress
+keyloop:
+ lda CH
+ cmp #KEY_NONE
+ beq keyloop
+
+ sta keycode ; got a keypress, save it for later
 
+ ; clear keypress so the loaded program won't see it
  lda #$ff
  sta CH
 
+ ; restore OS's colors and display list (back to regular E:)
  lda old_sdlstl
  sta SDLSTL
  lda old_sdlsth
@@ -74,48 +103,72 @@ loop:
  lda old_color2
  sta COLOR2
 
- cpx #KEY_1
- bne not_1
+ ; see what key was hit
  ldy #0
- beq setup_iocb
-
-not_1:
- cpx #KEY_2
- bne not_2
- ldy #1
- bne setup_iocb
-
-not_2:
- ; 3, or actually any other key
- rts
-
-setup_iocb:
- ldx #$10
- lda #$28 ; MyDOS XIO 40
+keytabloop:
+ lda keytab,y   ; get table entry
+ cmp #KEY_NONE  ; did we hit the end of the table with no match?
+ beq exit       ; yes, we're done
+ cmp keycode    ; no, see if this table entry matches
+ beq load_file  ; yes, use it
+ iny            ; no, look at next entry
+ bne keytabloop ; branch always
+
+ ; load and run the file (Y is index into filename table)
+load_file:
+ ldx #$10 ; IOCB #1
+ lda #$28 ; MyDOS XIO 40. 39 also works (same thing?), neither works on SDX
  sta ICCOM,x
- lda fntab_l,y
+ lda fntab_l,y  ; filename
  sta ICBAL,x
  lda fntab_h,y
  sta ICBAH,x
- lda fnlentab,y
+ lda fnlentab,y ; filename length
  sta ICBLL,x
  lda #0
  sta ICBLH,x
- jsr CIOV
+ jsr CIOV       ; pull the trigger
 
  ; CIOV should never return on success, so if we get here, give up.
- lda #0
- sta COLOR2
-hang: jmp hang
+ tya
+ pha ; save CIO return status (aka error number)
+ lda #<diskerrmsg
+ ldx #>diskerrmsg
+ jsr printmsg ; print error message
+ pla
+ jsr printdecb ; print error number
+ lda #<presskeymsg
+ ldx #>presskeymsg
+ jsr printmsg  ; press a key...
+
+ ; wait for a keypress, to give the user a chance to read the
+ ; error message.
+keyloop2:
+ lda CH
+ cmp #KEY_NONE
+ beq keyloop2
+ lda #KEY_NONE
+ sta CH
+exit:
  rts
 
 dla_filename: .byte "D:DLA.XEX"
 dla_fn_len = * - dla_filename
+
 csv_filename: .byte "D:DLA2CSV.XEX"
 csv_fn_len = * - csv_filename
 
+; these tables only have 2 entries, but could have many more if
+; we ever need them (up to 255).
 fntab_l:  .byte <dla_filename, <csv_filename
 fntab_h:  .byte >dla_filename, >csv_filename
+
 fnlentab: .byte dla_fn_len, csv_fn_len
 
+; KEY_NONE marks the end of this table.
+keytab: .byte KEY_1, KEY_2, KEY_NONE
+
+diskerrmsg:  .byte "I/O Error ",0
+presskeymsg: .byte $9b,"Press any key...",0
+
 xex_run main