401 lines
9.1 KiB
C++
401 lines
9.1 KiB
C++
//
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// NES 2A03
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//
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#include <assert.h>
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#include "nes_apu.h"
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namespace xgm
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{
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void NES_APU::sweep_sqr (int i)
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{
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int shifted = freq[i] >> sweep_amount[i];
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if (i == 0 && sweep_mode[i]) shifted += 1;
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sfreq[i] = freq[i] + (sweep_mode[i] ? -shifted : shifted);
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//DEBUG_OUT("shifted[%d] = %d (%d >> %d)¥n",i,shifted,freq[i],sweep_amount[i]);
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}
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void NES_APU::FrameSequence(int s)
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{
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//DEBUG_OUT("FrameSequence(%d)¥n",s);
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if (s > 3) return; // no operation in step 4
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// 240hz clock
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for (int i=0; i < 2; ++i)
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{
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bool divider = false;
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if (envelope_write[i])
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{
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envelope_write[i] = false;
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envelope_counter[i] = 15;
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envelope_div[i] = 0;
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}
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else
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{
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++envelope_div[i];
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if (envelope_div[i] > envelope_div_period[i])
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{
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divider = true;
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envelope_div[i] = 0;
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}
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}
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if (divider)
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{
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if (envelope_loop[i] && envelope_counter[i] == 0)
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envelope_counter[i] = 15;
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else if (envelope_counter[i] > 0)
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--envelope_counter[i];
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}
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}
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// 120hz clock
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if ((s&1) == 0)
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for (int i=0; i < 2; ++i)
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{
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if (!envelope_loop[i] && (length_counter[i] > 0))
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--length_counter[i];
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if (sweep_enable[i])
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{
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//DEBUG_OUT("Clock sweep: %d¥n", i);
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--sweep_div[i];
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if (sweep_div[i] <= 0)
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{
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sweep_sqr(i); // calculate new sweep target
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//DEBUG_OUT("sweep_div[%d] (0/%d)¥n",i,sweep_div_period[i]);
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//DEBUG_OUT("freq[%d]=%d > sfreq[%d]=%d¥n",i,freq[i],i,sfreq[i]);
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if (freq[i] >= 8 && sfreq[i] < 0x800 && sweep_amount[i] > 0) // update frequency if appropriate
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{
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freq[i] = sfreq[i] < 0 ? 0 : sfreq[i];
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}
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sweep_div[i] = sweep_div_period[i] + 1;
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//DEBUG_OUT("freq[%d]=%d¥n",i,freq[i]);
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}
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if (sweep_write[i])
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{
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sweep_div[i] = sweep_div_period[i] + 1;
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sweep_write[i] = false;
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}
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}
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}
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}
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INT32 NES_APU::calc_sqr (int i, UINT32 clocks)
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{
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static const INT16 sqrtbl[4][16] = {
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{0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
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{0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
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{0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0},
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{1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
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};
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scounter[i] -= clocks;
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while (scounter[i] < 0)
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{
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sphase[i] = (sphase[i] + 1) & 15;
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scounter[i] += freq[i] + 1;
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}
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INT32 ret = 0;
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if (length_counter[i] > 0 &&
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freq[i] >= 8 &&
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sfreq[i] < 0x800
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)
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{
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int v = envelope_disable[i] ? volume[i] : envelope_counter[i];
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ret = sqrtbl[duty[i]][sphase[i]] ? v : 0;
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}
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return ret;
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}
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bool NES_APU::Read (UINT32 adr, UINT32 & val, UINT32 id)
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{
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if (0x4000 <= adr && adr < 0x4008)
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{
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val |= reg[adr&0x7];
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return true;
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}
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else if(adr==0x4015)
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{
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val |= (length_counter[1]?2:0)|(length_counter[0]?1:0);
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return true;
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}
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else
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return false;
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}
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void NES_APU::Tick (UINT32 clocks)
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{
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out[0] = calc_sqr(0, clocks);
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out[1] = calc_sqr(1, clocks);
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}
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// ﾂ青ｶﾂ青ｬﾂつｳﾂづｪﾂづｩﾂ波ﾂ形ﾂづ個振ﾂ閉敖づ0-8191
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UINT32 NES_APU::Render (INT32 b[2])
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{
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out[0] = (mask & 1) ? 0 : out[0];
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out[1] = (mask & 2) ? 0 : out[1];
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INT32 m[2];
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if(option[OPT_NONLINEAR_MIXER])
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{
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INT32 voltage = square_table[out[0] + out[1]];
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m[0] = out[0] << 6;
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m[1] = out[1] << 6;
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INT32 ref = m[0] + m[1];
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if (ref > 0)
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{
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m[0] = (m[0] * voltage) / ref;
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m[1] = (m[1] * voltage) / ref;
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}
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else
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{
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m[0] = voltage;
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m[1] = voltage;
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}
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}
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else
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{
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m[0] = (out[0] * square_linear) / 15;
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m[1] = (out[1] * square_linear) / 15;
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}
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b[0] = m[0] * sm[0][0];
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b[0] += m[1] * sm[0][1];
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b[0] >>= 7;
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b[1] = m[0] * sm[1][0];
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b[1] += m[1] * sm[1][1];
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b[1] >>= 7;
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return 2;
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}
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NES_APU::NES_APU ()
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{
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SetClock (DEFAULT_CLOCK);
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SetRate (DEFAULT_RATE);
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option[OPT_UNMUTE_ON_RESET] = true;
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option[OPT_PHASE_REFRESH] = true;
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option[OPT_NONLINEAR_MIXER] = true;
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option[OPT_DUTY_SWAP] = false;
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option[OPT_NEGATE_SWEEP_INIT] = false;
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square_table[0] = 0;
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for(int i=1;i<32;i++)
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square_table[i]=(INT32)((8192.0*95.88)/(8128.0/i+100));
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square_linear = square_table[15]; // match linear scale to one full volume square of nonlinear
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for(int c=0;c<2;++c)
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for(int t=0;t<2;++t)
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sm[c][t] = 128;
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}
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NES_APU::‾NES_APU ()
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{
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}
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void NES_APU::Reset ()
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{
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int i;
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gclock = 0;
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mask = 0;
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for (int i=0; i<2; ++i)
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{
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scounter[i] = 0;
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sphase[i] = 0;
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duty[i] = 0;
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volume[i] = 0;
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freq[i] = 0;
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sfreq[i] = 0;
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sweep_enable[i] = 0;
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sweep_mode[i] = 0;
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sweep_write[i] = 0;
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sweep_div_period[i] = 0;
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sweep_div[i] = 1;
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sweep_amount[i] = 0;
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envelope_disable[i] = 0;
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envelope_loop[i] = 0;
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envelope_write[i] = 0;
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envelope_div_period[i] = 0;
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envelope_div[0] = 0;
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envelope_counter[i] = 0;
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length_counter[i] = 0;
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enable[i] = 0;
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}
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for (i = 0x4000; i < 0x4008; i++)
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Write (i, 0);
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Write (0x4015, 0);
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if (option[OPT_UNMUTE_ON_RESET])
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Write (0x4015, 0x0f);
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if (option[OPT_NEGATE_SWEEP_INIT])
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{
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Write (0x4001, 0x08);
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Write (0x4005, 0x08);
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}
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for (i = 0; i < 2; i++)
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out[i] = 0;
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SetRate(rate);
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}
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void NES_APU::SetOption (int id, int val)
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{
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if(id<OPT_END) option[id] = val;
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}
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void NES_APU::SetClock (double c)
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{
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clock = c;
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}
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void NES_APU::SetRate (double r)
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{
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rate = r ? r : DEFAULT_RATE;
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}
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void NES_APU::SetStereoMix(int trk, xgm::INT16 mixl, xgm::INT16 mixr)
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{
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if (trk < 0) return;
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if (trk > 1) return;
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sm[0][trk] = mixl;
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sm[1][trk] = mixr;
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}
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ITrackInfo *NES_APU::GetTrackInfo(int trk)
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{
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trkinfo[trk]._freq = freq[trk];
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if(freq[trk])
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trkinfo[trk].freq = clock/16/(freq[trk] + 1);
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else
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trkinfo[trk].freq = 0;
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trkinfo[trk].output = out[trk];
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trkinfo[trk].volume = volume[trk]+(envelope_disable[trk]?0:0x10)+(envelope_loop[trk]?0x20:0);
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trkinfo[trk].key =
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enable[trk] &&
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length_counter[trk] > 0 &&
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freq[trk] >= 8 &&
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sfreq[trk] < 0x800 &&
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(envelope_disable[trk] ? volume[trk] : (envelope_counter[trk] > 0));
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trkinfo[trk].tone = duty[trk];
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trkinfo[trk].max_volume = 15;
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return &trkinfo[trk];
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}
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bool NES_APU::Write (UINT32 adr, UINT32 val, UINT32 id)
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{
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int ch;
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static const UINT8 length_table[32] = {
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0x0A, 0xFE,
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0x14, 0x02,
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0x28, 0x04,
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0x50, 0x06,
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0xA0, 0x08,
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0x3C, 0x0A,
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0x0E, 0x0C,
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0x1A, 0x0E,
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0x0C, 0x10,
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0x18, 0x12,
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0x30, 0x14,
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0x60, 0x16,
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0xC0, 0x18,
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0x48, 0x1A,
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0x10, 0x1C,
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0x20, 0x1E
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};
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if (0x4000 <= adr && adr < 0x4008)
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{
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//DEBUG_OUT("$%04X = %02X¥n",adr,val);
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adr &= 0xf;
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ch = adr >> 2;
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switch (adr)
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{
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case 0x0:
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case 0x4:
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volume[ch] = val & 15;
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envelope_disable[ch] = (val >> 4) & 1;
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envelope_loop[ch] = (val >> 5) & 1;
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envelope_div_period[ch] = (val & 15);
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duty[ch] = (val >> 6) & 3;
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if (option[OPT_DUTY_SWAP])
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{
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if (duty[ch] == 1) duty[ch] = 2;
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else if (duty[ch] == 2) duty[ch] = 1;
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}
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break;
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case 0x1:
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case 0x5:
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sweep_enable[ch] = (val >> 7) & 1;
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sweep_div_period[ch] = (((val >> 4) & 7));
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sweep_mode[ch] = (val >> 3) & 1;
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sweep_amount[ch] = val & 7;
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sweep_write[ch] = true;
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sweep_sqr(ch);
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break;
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case 0x2:
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case 0x6:
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freq[ch] = val | (freq[ch] & 0x700) ;
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sweep_sqr(ch);
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break;
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case 0x3:
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case 0x7:
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freq[ch] = (freq[ch] & 0xFF) | ((val & 0x7) << 8) ;
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if (option[OPT_PHASE_REFRESH])
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sphase[ch] = 0;
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envelope_write[ch] = true;
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if (enable[ch])
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{
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length_counter[ch] = length_table[(val >> 3) & 0x1f];
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}
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sweep_sqr(ch);
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break;
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default:
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return false;
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}
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reg[adr] = val;
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return true;
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}
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else if (adr == 0x4015)
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{
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enable[0] = (val & 1) ? true : false;
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enable[1] = (val & 2) ? true : false;
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if (!enable[0])
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length_counter[0] = 0;
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if (!enable[1])
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length_counter[1] = 0;
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reg[adr-0x4000] = val;
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return true;
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}
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// 4017 is handled in nes_dmc.cpp
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//else if (adr == 0x4017)
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//{
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//}
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return false;
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}
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} // namespace xgm;
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