GSCats/loader.s

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;
; 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
;
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.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
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MAINENTRY = $020000
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.org $800
main:
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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
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.addr fileRead
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bne ioError
; Close the file
jsr PRODOS
.byte $cc
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.addr fileClose
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NATIVE
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; Copy code into bank 2
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ldx fileReadLen
lda #2
jsr copyBytes
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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
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; 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
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sta PRODOSRETURN
jml MAINENTRY
returnToProDOS:
SYNCDBR
EMULATION
rts
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ioError:
brk
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; 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
BITS16
plx
dex
dex
copyBytesLoop:
lda LOADBUFFER,x
copyBytesDest:
sta $010000,x
dex
dex
bpl copyBytesLoop
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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fileOpenCode:
.byte 3
.addr codePath
.addr $9200 ; 1k below BASIC.SYSTEM
.byte 0 ; Result (file handle)
.byte 0 ; Padding
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fileRead:
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.byte 4
.byte 1 ; File handle (we know it's gonna be 1)
.addr LOADBUFFER
.word BUFFERSIZE
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fileReadLen:
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.word 0 ; Result (bytes read)
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fileClose:
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.byte 1
.byte 1 ; File handle (we know it's gonna be 1)
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fileOpenSprites:
.byte 3
.addr spritePath
.addr $9200 ; 1k below BASIC.SYSTEM
.byte 0 ; Result (file handle)
.byte 0 ; Padding
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codePath:
pstring "/GSAPP/CODEBANK"
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spritePath:
pstring "/GSAPP/SPRITEBANK00"