bsnes/sfc/dsp/echo.cpp

136 lines
3.2 KiB
C++

#ifdef DSP_CPP
int DSP::calc_fir(int i, bool channel) {
int s = state.echo_hist[channel][state.echo_hist_pos + i + 1];
return (s * (int8)REG(fir + i * 0x10)) >> 6;
}
int DSP::echo_output(bool channel) {
int output = (int16)((state.t_main_out[channel] * (int8)REG(mvoll + channel * 0x10)) >> 7)
+ (int16)((state.t_echo_in [channel] * (int8)REG(evoll + channel * 0x10)) >> 7);
return sclamp<16>(output);
}
void DSP::echo_read(bool channel) {
unsigned addr = state.t_echo_ptr + channel * 2;
uint8 lo = smp.apuram[(uint16)(addr + 0)];
uint8 hi = smp.apuram[(uint16)(addr + 1)];
int s = (int16)((hi << 8) + lo);
state.echo_hist[channel].write(state.echo_hist_pos, s >> 1);
}
void DSP::echo_write(bool channel) {
if(!(state.t_echo_disabled & 0x20)) {
unsigned addr = state.t_echo_ptr + channel * 2;
int s = state.t_echo_out[channel];
smp.apuram[(uint16)(addr + 0)] = s;
smp.apuram[(uint16)(addr + 1)] = s >> 8;
}
state.t_echo_out[channel] = 0;
}
void DSP::echo_22() {
//history
state.echo_hist_pos++;
if(state.echo_hist_pos >= echo_hist_size) state.echo_hist_pos = 0;
state.t_echo_ptr = (uint16)((state.t_esa << 8) + state.echo_offset);
echo_read(0);
//FIR
int l = calc_fir(0, 0);
int r = calc_fir(0, 1);
state.t_echo_in[0] = l;
state.t_echo_in[1] = r;
}
void DSP::echo_23() {
int l = calc_fir(1, 0) + calc_fir(2, 0);
int r = calc_fir(1, 1) + calc_fir(2, 1);
state.t_echo_in[0] += l;
state.t_echo_in[1] += r;
echo_read(1);
}
void DSP::echo_24() {
int l = calc_fir(3, 0) + calc_fir(4, 0) + calc_fir(5, 0);
int r = calc_fir(3, 1) + calc_fir(4, 1) + calc_fir(5, 1);
state.t_echo_in[0] += l;
state.t_echo_in[1] += r;
}
void DSP::echo_25() {
int l = state.t_echo_in[0] + calc_fir(6, 0);
int r = state.t_echo_in[1] + calc_fir(6, 1);
l = (int16)l;
r = (int16)r;
l += (int16)calc_fir(7, 0);
r += (int16)calc_fir(7, 1);
state.t_echo_in[0] = sclamp<16>(l) & ~1;
state.t_echo_in[1] = sclamp<16>(r) & ~1;
}
void DSP::echo_26() {
//left output volumes
//(save sample for next clock so we can output both together)
state.t_main_out[0] = echo_output(0);
//echo feedback
int l = state.t_echo_out[0] + (int16)((state.t_echo_in[0] * (int8)REG(efb)) >> 7);
int r = state.t_echo_out[1] + (int16)((state.t_echo_in[1] * (int8)REG(efb)) >> 7);
state.t_echo_out[0] = sclamp<16>(l) & ~1;
state.t_echo_out[1] = sclamp<16>(r) & ~1;
}
void DSP::echo_27() {
//output
int outl = state.t_main_out[0];
int outr = echo_output(1);
state.t_main_out[0] = 0;
state.t_main_out[1] = 0;
//TODO: global muting isn't this simple
//(turns DAC on and off or something, causing small ~37-sample pulse when first muted)
if(REG(flg) & 0x40) {
outl = 0;
outr = 0;
}
//output sample to DAC
audio.sample(outl, outr);
}
void DSP::echo_28() {
state.t_echo_disabled = REG(flg);
}
void DSP::echo_29() {
state.t_esa = REG(esa);
if(!state.echo_offset) state.echo_length = (REG(edl) & 0x0f) << 11;
state.echo_offset += 4;
if(state.echo_offset >= state.echo_length) state.echo_offset = 0;
//write left echo
echo_write(0);
state.t_echo_disabled = REG(flg);
}
void DSP::echo_30() {
//write right echo
echo_write(1);
}
#endif