source/src/vm/sn76489an.cpp

   1 /*
   2         Skelton for retropc emulator
   3
   4         Author : Takeda.Toshiya
   5         Date   : 2006.08.18 -
   6
   7         [ SN76489AN ]
   8 */
   9
  10 #include "sn76489an.h"
  11
  12 //#ifdef HAS_SN76489
  13 // SN76489
  14 //#define NOISE_FB      0x4000
  15 //#define NOISE_DST_TAP 1
  16 //#define NOISE_SRC_TAP 2
  17 //#else
  18 // SN76489A, SN76496
  19 //#define NOISE_FB      0x10000
  20 //#define NOISE_DST_TAP 4
  21 //#define NOISE_SRC_TAP 8
  22 //#endif
  23 #define NOISE_MODE      ((regs[6] & 4) ? 1 : 0)
  24
  25 void SN76489AN::initialize()
  26 {
  27         DEVICE::initialize();
  28         if(osd->check_feature(_T("HAS_SN76489"))) {
  29                 _NOISE_FB = 0x4000;
  30                 _NOISE_DST_TAP = 1;
  31                 _NOISE_SRC_TAP = 1;
  32         } else {
  33                 _NOISE_FB = 0x10000;
  34                 _NOISE_DST_TAP = 4;
  35                 _NOISE_SRC_TAP = 8;
  36                 set_device_name(_T("SN76489AN PSG"));
  37         }
  38         mute = false;
  39         cs = we = true;
  40 }
  41
  42 void SN76489AN::reset()
  43 {
  44         touch_sound();
  45         for(int i = 0; i < 4; i++) {
  46                 ch[i].count = 0;
  47                 ch[i].period = 1;
  48                 ch[i].volume = 0;
  49                 ch[i].signal = false;
  50         }
  51         for(int i = 0; i < 8; i += 2) {
  52                 regs[i + 0] = 0;
  53                 regs[i + 1] = 0x0f;     // volume = 0
  54         }
  55         noise_gen = _NOISE_FB;
  56         ch[3].signal = false;
  57 }
  58
  59 void SN76489AN::write_io8(uint32_t addr, uint32_t data)
  60 {
  61         if(data & 0x80) {
  62                 index = (data >> 4) & 7;
  63                 int c = index >> 1;
  64
  65                 switch(index & 7) {
  66                 case 0: case 2: case 4:
  67                         touch_sound();
  68                         // tone : frequency
  69                         regs[index] = (regs[index] & 0x3f0) | (data & 0x0f);
  70                         ch[c].period = regs[index] ? regs[index] : 0x400;
  71 //                      ch[c].count = 0;
  72                         break;
  73                 case 1: case 3: case 5: case 7:
  74                         touch_sound();
  75                         // tone / noise : volume
  76                         regs[index] = data & 0x0f;
  77                         ch[c].volume = volume_table[data & 0x0f];
  78                         break;
  79                 case 6:
  80                         touch_sound();
  81                         // noise : frequency, mode
  82                         regs[6] = data;
  83                         data &= 3;
  84                         ch[3].period = (data == 3) ? (ch[2].period << 1) : (1 << (data + 5));
  85 //                      ch[3].count = 0;
  86                         noise_gen = _NOISE_FB;
  87                         ch[3].signal = false;
  88                         break;
  89                 }
  90         } else {
  91                 int c = index >> 1;
  92
  93                 switch(index & 0x07) {
  94                 case 0: case 2: case 4:
  95                         touch_sound();
  96                         // tone : frequency
  97                         regs[index] = (regs[index] & 0x0f) | (((uint16_t)data << 4) & 0x3f0);
  98                         ch[c].period = regs[index] ? regs[index] : 0x400;
  99 //                      ch[c].count = 0;
 100                         // update noise shift frequency
 101                         if(index == 4 && (regs[6] & 3) == 3) {
 102                                 ch[3].period = ch[2].period << 1;
 103                         }
 104                         break;
 105                 }
 106         }
 107 }
 108
 109 void SN76489AN::write_signal(int id, uint32_t data, uint32_t mask)
 110 {
 111         if(id == SIG_SN76489AN_MUTE) {
 112                 touch_sound();
 113                 mute = ((data & mask) != 0);
 114         } else if(id == SIG_SN76489AN_DATA) {
 115                 touch_sound();
 116                 val = data & mask;
 117         } else if(id == SIG_SN76489AN_CS) {
 118                 bool next = ((data & mask) != 0);
 119                 if(cs != next) {
 120                         if(!(cs = next) && !we) {
 121                                 write_io8(0, val);
 122                         }
 123                 }
 124         } else if(id == SIG_SN76489AN_CS) {
 125                 bool next = ((data & mask) != 0);
 126                 if(cs != next) {
 127                         cs = next;
 128                         if(!cs && !we) {
 129                                 write_io8(0, val);
 130                         }
 131                 }
 132         } else if(id == SIG_SN76489AN_WE) {
 133                 bool next = ((data & mask) != 0);
 134                 if(we != next) {
 135                         we = next;
 136                         if(!cs && !we) {
 137                                 write_io8(0, val);
 138                         }
 139                 }
 140         }
 141 }
 142
 143 void SN76489AN::mix(int32_t* buffer, int cnt)
 144 {
 145         if(mute) {
 146                 return;
 147         }
 148         for(int i = 0; i < cnt; i++) {
 149                 int32_t vol_l = 0, vol_r = 0;
 150                 for(int j = 0; j < 4; j++) {
 151                         if(!ch[j].volume) {
 152                                 continue;
 153                         }
 154                         bool prev_signal = ch[j].signal;
 155                         int prev_count = ch[j].count;
 156                         ch[j].count -= diff;
 157                         if(ch[j].count < 0) {
 158                                 ch[j].count += ch[j].period << 8;
 159                                 if(j == 3) {
 160                                         if(((noise_gen & _NOISE_DST_TAP) ? 1 : 0) ^ (((noise_gen & _NOISE_SRC_TAP) ? 1 : 0) * NOISE_MODE)) {
 161                                                 noise_gen >>= 1;
 162                                                 noise_gen |= _NOISE_FB;
 163                                         } else {
 164                                                 noise_gen >>= 1;
 165                                         }
 166                                         ch[3].signal = ((noise_gen & 1) != 0);
 167                                 } else {
 168                                         ch[j].signal = !ch[j].signal;
 169                                 }
 170                         }
 171                         int32_t sample = (prev_signal != ch[j].signal && prev_count < diff) ? (ch[j].volume * (2 * prev_count - diff)) / diff : ch[j].volume;
 172                         int32_t vol_tmp_l = apply_volume(sample, volume_l);
 173                         int32_t vol_tmp_r = apply_volume(sample, volume_r);
 174
 175                         vol_l += prev_signal ? vol_tmp_l : -vol_tmp_l;
 176                         vol_r += prev_signal ? vol_tmp_r : -vol_tmp_r;
 177                 }
 178                 *buffer++ += vol_l; // L
 179                 *buffer++ += vol_r; // R
 180         }
 181 }
 182
 183 void SN76489AN::set_volume(int ch, int decibel_l, int decibel_r)
 184 {
 185         volume_l = decibel_to_volume(decibel_l);
 186         volume_r = decibel_to_volume(decibel_r);
 187 }
 188
 189 void SN76489AN::initialize_sound(int rate, int clock, int volume)
 190 {
 191         // create gain
 192         double vol = volume;
 193         for(int i = 0; i < 15; i++) {
 194                 volume_table[i] = (int)vol;
 195                 vol /= 1.258925412;
 196         }
 197         volume_table[15] = 0;
 198         diff = (int)(16.0 * (double)clock / (double)rate + 0.5);
 199 }
 200
 201 #define STATE_VERSION   2
 202
 203 bool SN76489AN::process_state(FILEIO* state_fio, bool loading)
 204 {
 205         if(!state_fio->StateCheckUint32(STATE_VERSION)) {
 206                 return false;
 207         }
 208         if(!state_fio->StateCheckInt32(this_device_id)) {
 209                 return false;
 210         }
 211         state_fio->StateArray(regs, sizeof(regs), 1);
 212         state_fio->StateValue(index);
 213         for(int i = 0; i < array_length(ch); i++) {
 214                 state_fio->StateValue(ch[i].count);
 215                 state_fio->StateValue(ch[i].period);
 216                 state_fio->StateValue(ch[i].volume);
 217                 state_fio->StateValue(ch[i].signal);
 218         }
 219         state_fio->StateValue(noise_gen);
 220         state_fio->StateValue(mute);
 221         state_fio->StateValue(cs);
 222         state_fio->StateValue(we);
 223         state_fio->StateValue(val);
 224 //if(loading) {
 225         //touch_sound();
 226 //}
 227         return true;
 228 }