source/src/vm/pcm1bit.cpp

   1 /*
   2         Skelton for retropc emulator
   3
   4         Author : Takeda.Toshiya
   5         Date   : 2007.02.09 -
   6
   7         [ 1bit PCM ]
   8 */
   9
  10 #include "pcm1bit.h"
  11
  12 void PCM1BIT::initialize()
  13 {
  14         signal = false;
  15         on = true;
  16         mute = false;
  17         changed = 0;
  18         last_vol = 0;
  19
  20         register_frame_event(this);
  21 }
  22
  23 void PCM1BIT::reset()
  24 {
  25         prev_clock = current_clock();
  26         positive_clocks = negative_clocks = 0;
  27 }
  28
  29 void PCM1BIT::write_signal(int id, uint32 data, uint32 mask)
  30 {
  31         if(id == SIG_PCM1BIT_SIGNAL) {
  32                 bool next = ((data & mask) != 0);
  33                 if(signal != next) {
  34                         if(signal) {
  35                                 positive_clocks += passed_clock(prev_clock);
  36                         } else {
  37                                 negative_clocks += passed_clock(prev_clock);
  38                         }
  39                         prev_clock = current_clock();
  40                         // mute if signal is not changed in 2 frames
  41                         changed = 2;
  42                         signal = next;
  43                 }
  44         } else if(id == SIG_PCM1BIT_ON) {
  45                 on = ((data & mask) != 0);
  46         } else if(id == SIG_PCM1BIT_MUTE) {
  47                 mute = ((data & mask) != 0);
  48         }
  49 }
  50
  51 void PCM1BIT::event_frame()
  52 {
  53         if(changed) {
  54                 changed--;
  55         }
  56 }
  57
  58 void PCM1BIT::mix(int32* buffer, int cnt)
  59 {
  60         if(on && !mute && changed) {
  61                 if(signal) {
  62                         positive_clocks += passed_clock(prev_clock);
  63                 } else {
  64                         negative_clocks += passed_clock(prev_clock);
  65                 }
  66                 int clocks = positive_clocks + negative_clocks;
  67                 last_vol = clocks ? (max_vol * positive_clocks - max_vol * negative_clocks) / clocks : signal ? max_vol : -max_vol;
  68
  69                 for(int i = 0; i < cnt; i++) {
  70                         *buffer++ += last_vol; // L
  71                         *buffer++ += last_vol; // R
  72                 }
  73         } else if(last_vol > 0) {
  74                 // suppress petite noise when go to mute
  75                 for(int i = 0; i < cnt && last_vol != 0; i++, last_vol--) {
  76                         *buffer++ += last_vol; // L
  77                         *buffer++ += last_vol; // R
  78                 }
  79         } else if(last_vol < 0) {
  80                 // suppress petite noise when go to mute
  81                 for(int i = 0; i < cnt && last_vol != 0; i++, last_vol++) {
  82                         *buffer++ += last_vol; // L
  83                         *buffer++ += last_vol; // R
  84                 }
  85         }
  86         prev_clock = current_clock();
  87         positive_clocks = negative_clocks = 0;
  88 }
  89
  90 void PCM1BIT::init(int rate, int volume)
  91 {
  92         max_vol = volume;
  93 }
  94
  95 #define STATE_VERSION   2
  96
  97 void PCM1BIT::save_state(FILEIO* state_fio)
  98 {
  99         state_fio->FputUint32(STATE_VERSION);
 100         state_fio->FputInt32(this_device_id);
 101
 102         state_fio->FputBool(signal);
 103         state_fio->FputBool(on);
 104         state_fio->FputBool(mute);
 105         state_fio->FputInt32(changed);
 106         state_fio->FputUint32(prev_clock);
 107         state_fio->FputInt32(positive_clocks);
 108         state_fio->FputInt32(negative_clocks);
 109 }
 110
 111 bool PCM1BIT::load_state(FILEIO* state_fio)
 112 {
 113         if(state_fio->FgetUint32() != STATE_VERSION) {
 114                 return false;
 115         }
 116         if(state_fio->FgetInt32() != this_device_id) {
 117                 return false;
 118         }
 119         signal = state_fio->FgetBool();
 120         on = state_fio->FgetBool();
 121         mute = state_fio->FgetBool();
 122         changed = state_fio->FgetInt32();
 123         prev_clock = state_fio->FgetUint32();
 124         positive_clocks = state_fio->FgetInt32();
 125         negative_clocks = state_fio->FgetInt32();
 126
 127         // post process
 128         last_vol = 0;
 129         return true;
 130 }
 131