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 #include "../fileio.h"
  12
  13 void PCM1BIT::initialize()
  14 {
  15         signal = false;
  16         on = true;
  17         mute = false;
  18         changed = 0;
  19         last_vol = 0;
  20
  21         register_frame_event(this);
  22 }
  23
  24 void PCM1BIT::reset()
  25 {
  26         prev_clock = current_clock();
  27         positive_clocks = negative_clocks = 0;
  28 }
  29
  30 void PCM1BIT::write_signal(int id, uint32 data, uint32 mask)
  31 {
  32         if(id == SIG_PCM1BIT_SIGNAL) {
  33                 bool next = ((data & mask) != 0);
  34                 if(signal != next) {
  35                         if(signal) {
  36                                 positive_clocks += passed_clock(prev_clock);
  37                         } else {
  38                                 negative_clocks += passed_clock(prev_clock);
  39                         }
  40                         prev_clock = current_clock();
  41                         // mute if signal is not changed in 2 frames
  42                         changed = 2;
  43                         signal = next;
  44                 }
  45         } else if(id == SIG_PCM1BIT_ON) {
  46                 on = ((data & mask) != 0);
  47         } else if(id == SIG_PCM1BIT_MUTE) {
  48                 mute = ((data & mask) != 0);
  49         }
  50 }
  51
  52 void PCM1BIT::event_frame()
  53 {
  54         if(changed) {
  55                 changed--;
  56         }
  57 }
  58
  59 void PCM1BIT::mix(int32* buffer, int cnt)
  60 {
  61         if(on && !mute && changed) {
  62                 if(signal) {
  63                         positive_clocks += passed_clock(prev_clock);
  64                 } else {
  65                         negative_clocks += passed_clock(prev_clock);
  66                 }
  67                 int clocks = positive_clocks + negative_clocks;
  68                 last_vol = clocks ? (max_vol * positive_clocks - max_vol * negative_clocks) / clocks : signal ? max_vol : -max_vol;
  69
  70                 for(int i = 0; i < cnt; i++) {
  71                         *buffer++ += last_vol; // L
  72                         *buffer++ += last_vol; // R
  73                 }
  74         } else if(last_vol > 0) {
  75                 // suppress petite noise when go to mute
  76                 for(int i = 0; i < cnt && last_vol != 0; i++, last_vol--) {
  77                         *buffer++ += last_vol; // L
  78                         *buffer++ += last_vol; // R
  79                 }
  80         } else if(last_vol < 0) {
  81                 // suppress petite noise when go to mute
  82                 for(int i = 0; i < cnt && last_vol != 0; i++, last_vol++) {
  83                         *buffer++ += last_vol; // L
  84                         *buffer++ += last_vol; // R
  85                 }
  86         }
  87         prev_clock = current_clock();
  88         positive_clocks = negative_clocks = 0;
  89 }
  90
  91 void PCM1BIT::init(int rate, int volume)
  92 {
  93         max_vol = volume;
  94 }
  95
  96 #define STATE_VERSION   2
  97
  98 void PCM1BIT::save_state(FILEIO* state_fio)
  99 {
 100         state_fio->FputUint32(STATE_VERSION);
 101         state_fio->FputInt32(this_device_id);
 102
 103         state_fio->FputBool(signal);
 104         state_fio->FputBool(on);
 105         state_fio->FputBool(mute);
 106         state_fio->FputInt32(changed);
 107         state_fio->FputUint32(prev_clock);
 108         state_fio->FputInt32(positive_clocks);
 109         state_fio->FputInt32(negative_clocks);
 110 }
 111
 112 bool PCM1BIT::load_state(FILEIO* state_fio)
 113 {
 114         if(state_fio->FgetUint32() != STATE_VERSION) {
 115                 return false;
 116         }
 117         if(state_fio->FgetInt32() != this_device_id) {
 118                 return false;
 119         }
 120         signal = state_fio->FgetBool();
 121         on = state_fio->FgetBool();
 122         mute = state_fio->FgetBool();
 123         changed = state_fio->FgetInt32();
 124         prev_clock = state_fio->FgetUint32();
 125         positive_clocks = state_fio->FgetInt32();
 126         negative_clocks = state_fio->FgetInt32();
 127
 128         // post process
 129         last_vol = 0;
 130         return true;
 131 }
 132