gistfile1.asm

namespace mute	
// FLG register
flag:
	dw $000f		// length of the code
	lda #$6c
	sta $f2
	lda #$20		// unmute, disable_echo
	sta $f3
	cmp $f3, #$20
	bne flag

	// Lower Left Output Echo Volume
left:
	lda #$2c
	sta $f2
	lda $f3		// read current volume
	cmp #$10	// already at lowest?
	beq right
	dec		// decrement it
	sta $f3		// and write it back
	cmp $f3
	bne left

	// Lower Right Output Echo Volume
right:
	lda #$3c
	sta $f2
	lda $f3
	cmp #$10
	beq loop
	dec
	sta $f3
	cmp $f3
	bne right

loop:
	bra loop


namespace unmute
// FLG register
flag:
	dw $000f		// length of the code
	lda #$6c
	sta $f2
	lda #$20		// unmute, disable_echo
	sta $f3
	cmp $f3, #$20
	bne flag

	// Lower Left Output Echo Volume
left:
	lda #$2c
	sta $f2
	lda $f3		// read current volume
	cmp #$23	// already at desired volume?
	beq right
	inc		// increment it
	sta $f3		// and write it back
	cmp $f3
	bne left

	// Lower Right Output Echo Volume
right:
	lda #$3c
	sta $f2
	lda $f3
	cmp #$23
	beq loop
	inc
	sta $f3
	cmp $f3
	bne right

loop:
	bra loop