MSX PSG

/*
zcc +msx -lndos -create-app tone.c
bload"cas:",r
*/

# include <stdio.h>
# include <psg.h>

# define BOOL int
# define FALSE 0
# define TRUE 1

int snsmat(int line)
{
# asm
 ld a, l
 call $0141 ; SNSMAT
 ld l, a
 ld h, 0
# endasm
}

void main()
{
 BOOL press = FALSE;

 psg_init();
 sound(7, 076); // ch.A tone enable

 puts("Press A key.\n");

 for (;;) {
 int bits = snsmat(2);
 if (bits & 0x40) {
 if (press) {
 sound(8, 0);
 press = FALSE;
 }
 } else {
 if (! press) {
 sound(0, 0xfe);
 sound(1, 0);
 sound(8, 12);
 press = TRUE;
 }
 }
 }
}