GSCats/loader.s
2023-06-21 20:07:30 -07:00

268 lines
5.8 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 first half of code into bank 0
jsr PRODOS
.byte $ca
.addr fileRead
bne ioError
NATIVE
; Copy code into bank 2
ldx fileReadLen
lda #2
ldy #0
jsr copyBytes
EMULATION
; Load rest of code into bank 0 (needed if code size exceeds BUFFERSIZE)
jsr PRODOS
.byte $ca
.addr fileRead
bne ioError
; Close the file
jsr PRODOS
.byte $cc
.addr fileClose
NATIVE
; Copy rest of code into bank 2 (needed if code size exceeds BUFFERSIZE)
ldx fileReadLen
lda #2
ldy #BUFFERSIZE
jsr copyBytes
EMULATION
;;;;;;;;;;;;;;;;;;;;;
; Open the E1 code file
jsr PRODOS
.byte $c8
.addr fileOpenCodeE1
bne ioError
; Load the code into bank 0
jsr PRODOS
.byte $ca
.addr fileRead
bne ioError
; Close the file
jsr PRODOS
.byte $cc
.addr fileClose
jmp loadData
; Note that we skip E1 code bank loading now. This was used for the
; fill mode terrain renderer, which is disabled until further notice
; There isn't enough safe room in E1 to do everything we wanted and the fill
; mode rendering isn't useful enough to keep
NATIVE
; Copy code into bank E1
ldx fileReadLen
lda #$E1
ldy #$800 ; Must match terrain_e1 .org
jsr copyBytes
; Copy vram table into bank E1
; Note that there's a GS memory manager jump table at 1680 - 16BB
; in E1 that we have to work around. If we step on it, warm reboots and other
; critical things start to fail.
phb
lda #vramRowInvertedSpanLookupEnd-vramRowInvertedSpanLookup-1
ldx #vramRowInvertedSpanLookupEnd-1
ldy #$16C0 + vramRowInvertedSpanLookupEnd-vramRowInvertedSpanLookup-1 ; Must match terrain_e1 vramRowInvertedSpanLookup
mvp $e1,$00 ; Note that ca65 reverses src,dest. Grrr.
plb
EMULATION
ioError:
brk
;;;;;;;;;;;;;;;;;;;;;
loadData:
; 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
ldy #0
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
; This table lives here in the loader because we need to copy
; it to a specific free hole in bank E1
vramRowInvertedSpanLookup:
.word $9d00,$9c60,$9bc0,$9b20,$9a80,$99e0,$9940,$98a0,$9800,$9760,$96c0,$9620,$9580,$94e0,$9440,$93a0,$9300,$9260,$91c0,$9120
.word $9080,$8fe0,$8f40,$8ea0,$8e00,$8d60,$8cc0,$8c20,$8b80,$8ae0,$8a40,$89a0,$8900,$8860,$87c0,$8720,$8680,$85e0,$8540,$84a0
.word $8400,$8360,$82c0,$8220,$8180,$80e0,$8040,$7fa0,$7f00,$7e60,$7dc0,$7d20,$7c80,$7be0,$7b40,$7aa0,$7a00,$7960,$78c0,$7820
.word $7780,$76e0,$7640,$75a0,$7500,$7460,$73c0,$7320,$7280,$71e0,$7140,$70a0,$7000,$6f60,$6ec0,$6e20,$6d80,$6ce0,$6c40,$6ba0
.word $6b00,$6a60,$69c0,$6920,$6880,$67e0,$6740,$66a0,$6600,$6560,$64c0,$6420,$6380,$62e0,$6240,$61a0,$6100,$6060,$5fc0,$5f20
.word $5e80,$5de0,$5d40,$5ca0,$5c00,$5b60,$5ac0,$5a20,$5980,$58e0,$5840,$57a0,$5700,$5660,$55c0,$5520,$5480,$53e0,$5340,$52a0
.word $5200,$5160,$50c0,$5020,$4f80,$4ee0,$4e40,$4da0,$4d00,$4c60,$4bc0,$4b20,$4a80,$49e0,$4940,$48a0,$4800,$4760,$46c0,$4620
.word $4580,$44e0,$4440,$43a0,$4300,$4260,$41c0,$4120,$4080,$3fe0,$3f40,$3ea0,$3e00,$3d60,$3cc0,$3c20,$3b80,$3ae0,$3a40,$39a0
.word $3900,$3860,$37c0,$3720,$3680,$35e0,$3540,$34a0,$3400,$3360,$32c0,$3220,$3180,$30e0,$3040,$2fa0,$2f00,$2e60,$2dc0,$2d20
.word $2c80,$2be0,$2b40,$2aa0,$2a00,$2960,$28c0,$2820,$2780,$26e0,$2640,$25a0,$2500,$2460,$23c0,$2320,$2280,$21e0,$2140,$20a0
vramRowInvertedSpanLookupEnd:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; copyBytes
; Copy data from read buffer in bank 0 to
; offset any other bank. Must be in native mode.
;
; X = Length of data in bytes
; Y = Origin within bank
; A = Bank number of destination
; loadOffet : offset to start of copy destination
;
;TODO: Make this work for copying ALL of a 64k bank of code
;in chunks, as required by loader (which is using a bank 00 buffer)
copyBytes:
sty copyBytesDest+1
sty copyBytesDest2+1
phx
BITS8
sta copyBytesDest+3
sta copyBytesDest2+3
BITS16
plx
txa
and #1
bne copyBytesOdd
copyBytesEven:
dex
dex
copyBytesLoop:
lda LOADBUFFER,x
copyBytesDest:
sta $010000,x
dex
dex
cpx #$fffe ; X will wrap when we're done
bne copyBytesLoop
rts
copyBytesOdd:
dex
BITS8A
lda LOADBUFFER,x
copyBytesDest2:
sta $010000,x
BITS16
bra copyBytesEven
loadOffet:
.word 0
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
fileOpenCode:
.byte 3
.addr codePath
.addr $9200 ; 1k below BASIC.SYSTEM
.byte 0 ; Result (file handle)
.byte 0 ; Padding
fileOpenCodeE1:
.byte 3
.addr codePathE1
.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"
codePathE1:
pstring "/GSAPP/CODEBANKE1"
spritePath:
pstring "/GSAPP/SPRITEBANK"