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pcspeaker.cpp

/*
 *  Copyright (C) 2002-2004  The DOSBox Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <math.h>
#include "dosbox.h"
#include "mixer.h"
#include "timer.h"
#include "setup.h"
#include "pic.h"


#ifndef PI
#define PI 3.14159265358979323846
#endif

#define SPKR_ENTRIES 1024
#define SPKR_VOLUME 5000
//#define SPKR_SHIFT 8
#define SPKR_SPEED (float)((SPKR_VOLUME*2)/0.070f)

enum SPKR_MODES {
      SPKR_OFF,SPKR_ON,SPKR_PIT_OFF,SPKR_PIT_ON
};

struct DelayEntry {
      float index;
      float vol;
};

static struct {
      MixerChannel * chan;
      SPKR_MODES mode;
      Bitu pit_mode;
      Bitu rate;

      float pit_last;
      float pit_new_max,pit_new_half;
      float pit_max,pit_half;
      float pit_index;
      float volwant,volcur;
      Bitu last_ticks;
      float last_index;
      DelayEntry entries[SPKR_ENTRIES];
      Bitu used;
} spkr;

static void AddDelayEntry(float index,float vol) {
      if (spkr.used==SPKR_ENTRIES) {
            return;
      }
      spkr.entries[spkr.used].index=index;
      spkr.entries[spkr.used].vol=vol;
      spkr.used++;
}


static void ForwardPIT(float newindex) {
      float passed=(newindex-spkr.last_index);
      float delay_base=spkr.last_index;
      spkr.last_index=newindex;
      switch (spkr.pit_mode) {
      case 0:
            return;
      case 1:
            return;
      case 2:
            while (passed>0) {
                  /* passed the initial low cycle? */
                  if (spkr.pit_index>=spkr.pit_half) {
                        /* Start a new low cycle */
                        if ((spkr.pit_index+passed)>=spkr.pit_max) {
                              float delay=spkr.pit_max-spkr.pit_index;
                              delay_base+=delay;passed-=delay;
                              spkr.pit_last=-SPKR_VOLUME;
                              if (spkr.mode==SPKR_PIT_ON) AddDelayEntry(delay_base,spkr.pit_last);
                              spkr.pit_index=0;
                        } else {
                              spkr.pit_index+=passed;
                              return;
                        }
                  } else {
                        if ((spkr.pit_index+passed)>=spkr.pit_half) {
                              float delay=spkr.pit_half-spkr.pit_index;
                              delay_base+=delay;passed-=delay;
                              spkr.pit_last=SPKR_VOLUME;
                              if (spkr.mode==SPKR_PIT_ON) AddDelayEntry(delay_base,spkr.pit_last);
                              spkr.pit_index=spkr.pit_half;
                        } else {
                              spkr.pit_index+=passed;
                              return;
                        }
                  }
            }
            break;
            //END CASE 2
      case 3:
            while (passed>0) {
                  /* Determine where in the wave we're located */
                  if (spkr.pit_index>=spkr.pit_half) {
                        if ((spkr.pit_index+passed)>=spkr.pit_max) {
                              float delay=spkr.pit_max-spkr.pit_index;
                              delay_base+=delay;passed-=delay;
                              spkr.pit_last=SPKR_VOLUME;
                              if (spkr.mode==SPKR_PIT_ON) AddDelayEntry(delay_base,spkr.pit_last);
                              spkr.pit_index=0;
                              /* Load the new count */
                              spkr.pit_half=spkr.pit_new_half;
                              spkr.pit_max=spkr.pit_new_max;
                        } else {
                              spkr.pit_index+=passed;
                              return;
                        }
                  } else {
                        if ((spkr.pit_index+passed)>=spkr.pit_half) {
                              float delay=spkr.pit_half-spkr.pit_index;
                              delay_base+=delay;passed-=delay;
                              spkr.pit_last=-SPKR_VOLUME;
                              if (spkr.mode==SPKR_PIT_ON) AddDelayEntry(delay_base,spkr.pit_last);
                              spkr.pit_index=spkr.pit_half;
                        } else {
                              spkr.pit_index+=passed;
                              return;
                        }
                  }
            }
            break;
            //END CASE 3
      case 4:
            if (spkr.pit_index<spkr.pit_max) {
                  /* Check if we're gonna pass the end this block */
                  if (spkr.pit_index+passed>=spkr.pit_max) {
                        float delay=spkr.pit_max-spkr.pit_index;
                        delay_base+=delay;passed-=delay;
                        spkr.pit_last=-SPKR_VOLUME;
                        if (spkr.mode==SPKR_PIT_ON) AddDelayEntry(delay_base,spkr.pit_last);                      //No new events unless reprogrammed
                        spkr.pit_index=spkr.pit_max;
                  } else spkr.pit_index+=passed;
            }
            break;
            //END CASE 4
      }
}

void PCSPEAKER_SetCounter(Bitu cntr,Bitu mode) {
      if (!spkr.last_ticks) {
            spkr.chan->Enable(true);
            spkr.last_index=0;
      }
      spkr.last_ticks=PIC_Ticks;
      float newindex=PIC_TickIndex();
      ForwardPIT(newindex);
      switch (mode) {
      case 0:           /* Mode 0 one shot, used with realsound */
            if (spkr.mode!=SPKR_PIT_ON) return;
            if (cntr>80) { 
                  cntr=80;
            }
            spkr.pit_last=((float)cntr-40)*(SPKR_VOLUME/40.0f);
            AddDelayEntry(newindex,spkr.pit_last);
            spkr.pit_index=0;
            break;
      case 1:
            if (spkr.mode!=SPKR_PIT_ON) return;
            spkr.pit_last=SPKR_VOLUME;
            AddDelayEntry(newindex,spkr.pit_last);
            break;
      case 2:                 /* Single cycle low, rest low high generator */
            spkr.pit_index=0;
            spkr.pit_last=-SPKR_VOLUME;
            AddDelayEntry(newindex,spkr.pit_last);
            spkr.pit_half=(1000.0f/PIT_TICK_RATE)*1;
            spkr.pit_max=(1000.0f/PIT_TICK_RATE)*cntr;
            break;
      case 3:           /* Square wave generator */
            if (cntr<=40) {
                  /* Makes DIGGER sound better */
                  spkr.pit_last=0;
                  spkr.pit_mode=0;
                  return;
            }
            spkr.pit_new_max=(1000.0f/PIT_TICK_RATE)*cntr;
            spkr.pit_new_half=spkr.pit_new_max/2;
            break;
      case 4:           /* Software triggered strobe */
            spkr.pit_last=SPKR_VOLUME;
            AddDelayEntry(newindex,spkr.pit_last);
            spkr.pit_index=0;
            spkr.pit_max=(1000.0f/PIT_TICK_RATE)*cntr;
            break;
      default:
#if C_DEBUG
            LOG_MSG("Unhandled speaker mode %d",mode);
#endif
            return;
      }
      spkr.pit_mode=mode;
}

void PCSPEAKER_SetType(Bitu mode) {
      if (!spkr.last_ticks) {
            spkr.chan->Enable(true);
            spkr.last_index=0;
      }
      spkr.last_ticks=PIC_Ticks;
      float newindex=PIC_TickIndex();
      ForwardPIT(newindex);
      switch (mode) {
      case 0:
      spkr.mode=SPKR_OFF;
            AddDelayEntry(newindex,-SPKR_VOLUME);
            break;
      case 1:
            spkr.mode=SPKR_PIT_OFF;
            AddDelayEntry(newindex,-SPKR_VOLUME);
            break;
      case 2:
            spkr.mode=SPKR_ON;
            AddDelayEntry(newindex,SPKR_VOLUME);
            break;
      case 3:
            if (spkr.mode!=SPKR_PIT_ON) {
                  AddDelayEntry(newindex,spkr.pit_last);
            }
            spkr.mode=SPKR_PIT_ON;
            break;
      };
}

static void PCSPEAKER_CallBack(Bitu len) {
      Bit16s * stream=(Bit16s*)MixTemp;
      ForwardPIT(1);
      spkr.last_index=0;
      Bitu count=len;
      Bitu pos=0;
      float sample_base=0;
      float sample_add=(1.0001f)/len;
      while (count--) {
            float index=sample_base;
            sample_base+=sample_add;
            float end=sample_base;
            double value=0;
            while(index<end) {
                  /* Check if there is an upcoming event */
                  if (spkr.used && spkr.entries[pos].index<=index) {
                        spkr.volwant=spkr.entries[pos].vol;
                        pos++;spkr.used--;
                        continue;
                  }
                  float vol_end;
                  if (spkr.used && spkr.entries[pos].index<end) {
                        vol_end=spkr.entries[pos].index;
                  } else vol_end=end;
                  float vol_len=vol_end-index;
            /* Check if we have to slide the volume */
                  float vol_diff=spkr.volwant-spkr.volcur;
                  if (vol_diff == 0) {
                        value+=spkr.volcur*vol_len;
                        index+=vol_len;
                  } else {
                        /* Check how long it will take to goto new level */
                        float vol_time=fabs(vol_diff)/SPKR_SPEED;
                        if (vol_time<=vol_len) {
                              /* Volume reaches endpoint in this block, calc until that point */
                              value+=vol_time*spkr.volcur;
                              value+=vol_time*vol_diff/2;
                              index+=vol_time;
                              spkr.volcur=spkr.volwant;
                        } else {
                              /* Volume still not reached in this block */
                              value+=spkr.volcur*vol_len;
                              if (vol_diff<0) {
                                    value-=(SPKR_SPEED*vol_len*vol_len)/2;
                                    spkr.volcur-=SPKR_SPEED*vol_len;
                              } else {
                                    value+=(SPKR_SPEED*vol_len*vol_len)/2;
                                    spkr.volcur+=SPKR_SPEED*vol_len;
                              }
                              index+=vol_len;
                        }
                  }
            }
            *stream++=(Bit16s)(value/sample_add);
      }
      spkr.chan->AddSamples_m16(len,(Bit16s*)MixTemp);
      if ((spkr.last_ticks+10000)<PIC_Ticks) {
            spkr.last_ticks=0;
            spkr.chan->Enable(false);
      }
}

void PCSPEAKER_Init(Section* sec) {
      Section_prop * section=static_cast<Section_prop *>(sec);
      if(!section->Get_bool("pcspeaker")) return;
      spkr.mode=SPKR_OFF;
      spkr.last_ticks=0;
      spkr.last_index=0;
      spkr.rate=section->Get_int("pcrate");
      spkr.pit_max=(1000.0f/PIT_TICK_RATE)*65535;
      spkr.pit_half=spkr.pit_max/2;
      spkr.pit_new_max=spkr.pit_max;
      spkr.pit_new_half=spkr.pit_half;
      spkr.pit_index=0;
      spkr.used=0;
      /* Register the sound channel */
      spkr.chan=MIXER_AddChannel(&PCSPEAKER_CallBack,spkr.rate,"SPKR");
}

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