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;
; In most cases where the SID file is known this might work:
;
.comment
*= $1000
music .binary "music.sid", $7e; skip header and load
*= $0801 ; C64 BASIC header
.word (+), 2021
.null $9e, format("%4d", start)
+ .word 0
start lda #0
jsr music ; initialize
lp bit $d011
bpl lp
- bit $d011
bmi -
jsr music+3 ; call play every frame
jmp lp
.endc
;
; However SID files can have all sorts of load/init/play addresses
; and might not always have the same length of header either.
;
; So the following function tries to figure these details out.
loadsid .function _data : binary; use binary() for this parameter
_data_at := _data[[$7,$6]] ; data offset (big endian)
_load := _data[[$9,$8]] ; load address (big endian)
_init := _data[[$b,$a]] ; init address (big endian)
_play := _data[[$d,$c]] ; play address (big endian)
; dump music data after the header (and the optional loading address)
_sid .text _data[_data_at + (_load != 0 ? 0 : 2):]
; if load address is zero then it's the first 2 bytes of music data
_sid.load = _load != 0 ? _load : _data[_data_at + [0, 1]]
_sid.init = _init != 0 ? _init : _load
_sid.play = _play ; put results into constants
.endf _sid ; and return them
; There's a lot more information in the header, however that would make
; this example unnecessary complicated so it's left as an exercise
; to the reader.
;
*= music.load ; set PC to load address
music #loadsid "music.sid" ; load this file as music
* = $0801 ; C64 BASIC header
.word (+), 2021
.null $9e, format("%4d", start)
+ .word 0
start lda #0
jsr music.init ; initialize
lp bit $d011
bpl lp
- bit $d011
bmi -
jsr music.play ; call play every frame
jmp lp
|
