Write an asm sub in a .s file (then add to project makefile etc):

.globl CDDA_command CDDA_command: move.w 6(a7), d0 movem.l d2-d7/a2-a6, -(a7) jsr 0xc0056a movem.l (a7)+, d2-d7/a2-a6 rts
Declare it somewhere in a .h file:
void CDDA_command(ushort cmd);
I'm not sure if the bios call scraps the registers, registers push/pop around the call might be unnecessary.


Staying in C, it should be something looking like:
__asm__ ( "move.l %0, %%d0 \n" "movem.l %%d2-%%d7/%%a2-%%a6, -(%%a7) \n" "jsr 0xc0056a \n" "movem.l (%%a7)+, %%d2-%%d7/%%a2-%%a6 \n" : :"r"(/*CDDA code expression*/) :"d0", "d1", "a0", "a1", "cc" );I hardly ever use this method tho, so it might need some corrections.