GSCats/loader.s
2017-10-08 16:46:35 -07:00

161 lines
2.5 KiB
ArmAsm

;
; loader
; A very simplistic code loader designed to manage
; GS code under ProDOS 8 (if it's good enough for Will Harvey...)
;
; Created by Quinn Dunki on 7/29/17
;
.include "equates.s"
.include "macros.s"
LOADBUFFER = $1000 ; Clear of this loader code
BUFFERSIZE = $8200 ; About max size we can fit between buffer and this loader code
MAINENTRY = $020000
.org $800
main:
OP8 ; We launch in emulation. Stay there for now
; Open the main code file
jsr PRODOS
.byte $c8
.addr fileOpenCode
bne ioError
; Load the code into bank 0
jsr PRODOS
.byte $ca
.addr fileRead
bne ioError
; Close the file
jsr PRODOS
.byte $cc
.addr fileClose
NATIVE
; Copy code into bank 2
ldx fileReadLen
lda #2
jsr copyBytes
EMULATION
; Open the sprite bank file
jsr PRODOS
.byte $c8
.addr fileOpenSprites
bne ioError
; Load the compiled sprites into bank 0
jsr PRODOS
.byte $ca
.addr fileRead
bne ioError
; Close the file
jsr PRODOS
.byte $cc
.addr fileClose
NATIVE
; Copy sprites into bank 3
ldx fileReadLen
lda #3
jsr copyBytes
; Set up a long jump into bank 2, and
; a way for game code to get back here to exit
; properly to ProDOS 8
lda #returnToProDOS
sta PRODOSRETURN
jml MAINENTRY
returnToProDOS:
SYNCDBR
EMULATION
rts
ioError:
brk
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; copyBytes
; Copy data from read buffer in bank 0 to
; bottom of any other bank. Must be in native mode.
;
; X = Length of data in bytes
; A = Bank number of destination
;
copyBytes:
phx
BITS8
sta copyBytesDest+3
sta copyBytesDest2+3
BITS16
plx
txa
and #1
bne copyBytesOdd
copyBytesEven:
dex
dex
copyBytesLoop:
lda LOADBUFFER,x
copyBytesDest:
sta $010000,x
dex
dex
bpl copyBytesLoop
rts
copyBytesOdd:
dex
BITS8A
lda LOADBUFFER,x
copyBytesDest2:
sta $010000,x
BITS16
bra copyBytesEven
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
fileOpenCode:
.byte 3
.addr codePath
.addr $9200 ; 1k below BASIC.SYSTEM
.byte 0 ; Result (file handle)
.byte 0 ; Padding
fileRead:
.byte 4
.byte 1 ; File handle (we know it's gonna be 1)
.addr LOADBUFFER
.word BUFFERSIZE
fileReadLen:
.word 0 ; Result (bytes read)
fileClose:
.byte 1
.byte 1 ; File handle (we know it's gonna be 1)
fileOpenSprites:
.byte 3
.addr spritePath
.addr $9200 ; 1k below BASIC.SYSTEM
.byte 0 ; Result (file handle)
.byte 0 ; Padding
codePath:
pstring "/GSAPP/CODEBANK"
spritePath:
pstring "/GSAPP/SPRITEBANK00"