bsnes/higan/gb/apu/wave/wave.cpp

103 lines
2.0 KiB
C++
Executable File

#ifdef APU_CPP
void APU::Wave::run() {
if(period && --period == 0) {
period = 2 * (2048 - frequency);
pattern_sample = pattern[++pattern_offset];
}
uint4 sample = pattern_sample >> volume_shift;
if(enable == false) sample = 0;
output = sample;
}
void APU::Wave::clock_length() {
//if(counter && length) {
// if(--length == 0) enable = false;
//}
if(enable && counter) {
if(++length == 0) enable = false;
}
}
void APU::Wave::write(unsigned r, uint8 data) {
if(r == 0) { //$ff1a NR30
dac_enable = data & 0x80;
if(dac_enable == false) enable = false;
}
if(r == 1) { //$ff1b NR31
//length = 256 - data;
length = data;
}
if(r == 2) { //$ff1c NR32
switch((data >> 5) & 3) {
case 0: volume_shift = 4; break; // 0%
case 1: volume_shift = 0; break; //100%
case 2: volume_shift = 1; break; // 50%
case 3: volume_shift = 2; break; // 25%
}
}
if(r == 3) { //$ff1d NR33
frequency = (frequency & 0x0700) | data;
}
if(r == 4) { //$ff1e NR34
bool initialize = data & 0x80;
counter = data & 0x40;
frequency = ((data & 7) << 8) | (frequency & 0x00ff);
if(initialize) {
enable = dac_enable;
period = 2 * (2048 - frequency);
pattern_offset = 0;
//if(length == 0) length = 256;
}
}
}
void APU::Wave::write_pattern(unsigned p, uint8 data) {
p <<= 1;
pattern[p + 0] = (data >> 4) & 15;
pattern[p + 1] = (data >> 0) & 15;
}
void APU::Wave::power() {
enable = 0;
dac_enable = 0;
volume_shift = 0;
frequency = 0;
counter = 0;
random_lfsr r;
for(auto &n : pattern) n = r() & 15;
output = 0;
length = 0;
period = 0;
pattern_offset = 0;
pattern_sample = 0;
}
void APU::Wave::serialize(serializer &s) {
s.integer(enable);
s.integer(dac_enable);
s.integer(volume_shift);
s.integer(frequency);
s.integer(counter);
s.array(pattern);
s.integer(output);
s.integer(length);
s.integer(period);
s.integer(pattern_offset);
s.integer(pattern_sample);
}
#endif