example.rs

enum voiceRegisters {
    v_voll = 0x00,
    v_volr = 0x01,
    v_pitchl = 0x02,
    v_pitchh = 0x03,
    v_srcn = 0x04,
    v_adsr0 = 0x05,
    v_adsr1 = 0x06,
    v_gain = 0x07,
    v_envx = 0x08,
    v_outx = 0x09,
}

//using this as a basis
fn update_voice_vol(addr: isize, state: &mut State) {
  let mut l = state.regs[addr + voiceRegisters::v_voll];
  let mut r = state.regs[addr + voiceRegisters::v_volr];
  if l*r < state.surround_threshold {
    //signs differ, so negate those that are negative
    l ^= l >> 7;
    r ^= r >> 7;
  }
  let &mut v:Voice = state.voices[addr >> 4];
  let enabled:isize = v.enabled;
  v.volume[0] = l & enabled;
  v.volume[1] = r & enabled;
}