prog8/examples/cx16/chunkedfile/mcf.p8

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%import syslib
%import string
; Streaming routine for MCF files (multipurpose chunk format):
; 1. call open()
; 2. set callbacks if needed; set_callbacks()
; 3. set bonk ram (cartridge ram) load buffer, if needed; set_bonkbuffer()
; 4. call stream() in a loop
; 5. call close() if you want to cleanup halfway through for some reason
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mcf {
uword loadlist_buf = memory("loadlist", 256, 0)
uword @zp loadlist_ptr
uword bonkbuffer
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bool needs_loadlist
ubyte file_channel
sub open(str filename, ubyte drive, ubyte channel) -> bool {
cbm.SETNAM(string.length(filename), filename)
cbm.SETLFS(channel, drive, 2)
void cbm.OPEN()
if_cc {
if cbm.READST()==0 {
void cbm.CHKIN(channel)
loadlist_ptr = loadlist_buf
needs_loadlist = true
return true
}
}
close()
return false
}
sub close() {
cbm.CLRCHN()
cbm.CLOSE(file_channel)
}
asmsub set_callbacks(uword getbuffer_routine @R0, uword processchunk_routine @R1) {
%asm {{
lda cx16.r0
ldy cx16.r0+1
sta p8_mcf.p8_stream.getbuffer_call+1
sty p8_mcf.p8_stream.getbuffer_call+2
lda cx16.r1
ldy cx16.r1+1
sta p8_mcf.p8_stream.processchunk_call+1
sty p8_mcf.p8_stream.processchunk_call+2
rts
}}
}
sub set_bonkbuffer(uword buffer) {
; needs to be a buffer of 256 bytes (1 page)
bonkbuffer = buffer
}
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sub stream() {
repeat {
if needs_loadlist {
if not read_loadlist() {
sys.set_carry()
return
}
needs_loadlist = false
}
while (loadlist_ptr-loadlist_buf)<256 {
when @(loadlist_ptr) {
255 -> {
; simply ignore this byte
loadlist_ptr++
}
254 -> {
; End of File
close()
sys.set_carry()
return
}
253 -> {
; pause streaming
cx16.r0 = peekw(loadlist_ptr+1)
loadlist_ptr+=6
sys.clear_carry()
return
}
252 -> {
; load into vram
blockload_vram(peekw(loadlist_ptr+1), peek(loadlist_ptr+3), peekw(loadlist_ptr+4))
loadlist_ptr+=6
}
251 -> {
; load into system ram
blockload_ram(peekw(loadlist_ptr+1), peek(loadlist_ptr+3), peekw(loadlist_ptr+4))
loadlist_ptr+=6
}
250 -> {
; bonk ram (cartridge ram)
; This cannot use MACPTR (because the kernal rom isn't banked in)
; so we have to load it into a buffer and copy it manually.
; Because this will be rarely used, the buffer is not allocated here to save memory, and instead
; the user has to set it with the config routine when the program wants to use this chunk type.
blockload_bonkram(peekw(loadlist_ptr+1), peek(loadlist_ptr+3), peekw(loadlist_ptr+4))
loadlist_ptr+=6
}
249 -> {
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; dummy chunk
blockload_dummy(peekw(loadlist_ptr+1))
loadlist_ptr+=6
}
else -> {
; custom chunk
uword @shared chunksize = peekw(loadlist_ptr+1)
%asm {{
lda (p8_mcf.p8_loadlist_ptr)
ldx p8_chunksize
ldy p8_chunksize+1
getbuffer_call jsr $ffff ; modified
bcc +
rts ; fail - exit as if EOF
+ sta cx16.r1L
stx cx16.r0
sty cx16.r0+1
}}
blockload_ram(chunksize, cx16.r1L, cx16.r0)
loadlist_ptr += 6
%asm {{
processchunk_call jsr $ffff ; modified
bcc +
rts
+
}}
}
}
}
needs_loadlist = true
}
}
sub read_loadlist() -> bool {
blockload_ram(256, cx16.getrambank(), loadlist_buf)
if loadlist_buf[0]!=sc:'L' or loadlist_buf[1]!=sc:'L' or loadlist_buf[2]!=1
return false ; header error
loadlist_ptr = loadlist_buf+4
}
sub blockload_vram(uword size, ubyte bank, uword address) {
cx16.VERA_CTRL = 0
cx16.VERA_ADDR_L = lsb(address)
cx16.VERA_ADDR_M = msb(address)
cx16.VERA_ADDR_H = bank | %00010000 ; enable vera auto increment
while size {
size -= readblock(size, &cx16.VERA_DATA0, true)
}
}
sub blockload_dummy(uword size) {
ubyte buffer
while size {
size -= readblock(size, &buffer, true)
}
}
sub blockload_ram(uword size, ubyte bank, uword address) {
ubyte orig_ram_bank = cx16.getrambank()
cx16.rambank(bank)
cx16.r3 = address
while size {
cx16.r2 = readblock(size, cx16.r3, false)
size -= cx16.r2
cx16.r3 += cx16.r2
}
cx16.rambank(orig_ram_bank)
}
sub blockload_bonkram(uword size, ubyte bonk, uword address) {
ubyte orig_rom_bank = cx16.getrombank()
cx16.r3 = address
while size {
ubyte readsize = 255
if msb(size)==0
readsize = lsb(size)
cx16.r2 = cx16.MACPTR(readsize, bonkbuffer, false) ; can't MACPTR directly to bonk ram
cx16.rombank(bonk)
sys.memcopy(bonkbuffer, cx16.r3, cx16.r2) ; copy to bonk ram
cx16.rombank(orig_rom_bank)
size -= cx16.r2
cx16.r3 += cx16.r2
}
}
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sub readblock(uword size, uword address, bool dontAdvance) -> uword {
if msb(size)>=2
return cx16.MACPTR(0, address, dontAdvance) ; read 512 bytes
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if msb(size)
return cx16.MACPTR(255, address, dontAdvance) ; read 255 bytes
return cx16.MACPTR(lsb(size), address, dontAdvance) ; read remaining number of bytes
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}
}