source/src/vm/pv1000/psg.cpp

   1 /*
   2         CASIO PV-1000 Emulator 'ePV-1000'
   3
   4         Author : Takeda.Toshiya
   5         Date   : 2006.11.16 -
   6
   7         [ psg ]
   8 */
   9
  10 #include <math.h>
  11 #include "./psg.h"
  12
  13 #define PSG_CLOCK
  14 #define PSG_VOLUME      8192
  15
  16 void PSG::reset()
  17 {
  18         touch_sound();
  19         memset(ch, 0, sizeof(ch));
  20 }
  21
  22 void PSG::write_io8(uint32_t addr, uint32_t data)
  23 {
  24         touch_sound();
  25         ch[addr & 3].period = 0x3f - (data & 0x3f);
  26 }
  27
  28 void PSG::initialize_sound(int rate)
  29 {
  30         diff = (int)(1.3 * (double)CPU_CLOCKS / (double)rate + 0.5);
  31 }
  32
  33 void PSG::mix(int32_t* buffer, int cnt)
  34 {
  35         // create sound buffer
  36         for(int i = 0; i < cnt; i++) {
  37                 int vol = 0;
  38                 for(int j = 0; j < 3; j++) {
  39                         if(!ch[j].period) {
  40                                 continue;
  41                         }
  42                         bool prev_signal = ch[j].signal;
  43                         int prev_count = ch[j].count;
  44                         ch[j].count -= diff;
  45                         if(ch[j].count < 0) {
  46                                 ch[j].count += ch[j].period << 8;
  47                                 ch[j].signal = !ch[j].signal;
  48                         }
  49                         int vol_tmp = (prev_signal != ch[j].signal && prev_count < diff) ? (PSG_VOLUME * (2 * prev_count - diff)) / diff : PSG_VOLUME;
  50                         vol += prev_signal ? vol_tmp : -vol_tmp;
  51                 }
  52                 *buffer++ += apply_volume(vol, volume_l); // L
  53                 *buffer++ += apply_volume(vol, volume_l); // R
  54         }
  55 }
  56
  57 void PSG::set_volume(int ch, int decibel_l, int decibel_r)
  58 {
  59         volume_l = decibel_to_volume(decibel_l);
  60         volume_r = decibel_to_volume(decibel_r);
  61 }
  62
  63 #define STATE_VERSION   1
  64
  65 bool PSG::process_state(FILEIO* state_fio, bool loading)
  66 {
  67         if(!state_fio->StateCheckUint32(STATE_VERSION)) {
  68                 return false;
  69         }
  70         if(!state_fio->StateCheckInt32(this_device_id)) {
  71                 return false;
  72         }
  73         for(int i = 0; i < 3; i++) {
  74                 state_fio->StateInt32(ch[i].period);
  75         }
  76         return true;
  77 }