sound.fab

vars /sound
    UU tri_pitch = 0
    UU sq1_pitch = 0
    U sq1_duty = 0
    U sq1_vol = $0
    UU sq2_pitch = 0
    U sq2_duty = 0
    U sq2_vol = $0

fn reset_audio()

// we need to handle sq pitch separately because setting high resets
// the duty cycle.

fn set_sq1_timbre()
    fence
    {SQ1_VOL}((sq1_duty << 6) | %110000 | (sq1_vol & $F))
    fence
    
fn set_sq1_pitch()
    fence
    {SQ1_LO}(sq1_pitch.a)
    {SQ1_HI}(sq1_pitch.b & %111)
    fence

fn set_sq2_timbre()
    fence
    {SQ2_VOL}((sq2_duty << 6) | %110000 | (sq2_vol & $F))
    fence
    
fn set_sq2_pitch()
    fence
    {SQ2_LO}(sq2_pitch.a)
    {SQ2_HI}(sq2_pitch.b & %111)
    fence

// works like normal, plays note for exactly one frame
fn play_tri()
    fence
    {TRI_LINEAR}($04) // play for one frame
    {TRI_LO}(tri_pitch.a)
    {TRI_HI}(tri_pitch.b & %111)
    fence