berzerk.c

这个是延伸mame的在wince平台下的游戏模拟器的代码

/*
 * Berzerk/Frenzy Soundhardware Driver
 * Copyright Alex Judd 1997/98
 * V1.1 for Mame 0.31 13March98
 *
 * these were the original values but I have adjusted them to take account of the
 * default sample rate of 22050. I guess the original samples were at 24000.
 * case 0 : samplefrequency = 19500;
 * case 1 : samplefrequency = 20800;
 * case 2 : samplefrequency = 22320;
 * case 3 : samplefrequency = 24000;
 * case 4 : samplefrequency = 26000;
 * case 5 : samplefrequency = 28400;
 * case 6 : samplefrequency = 31250;
 * case 7 : samplefrequency = 34700;
 *
 */

#include "driver.h"
#include <math.h>



#define VOICE_PITCH_MODULATION	/* remove this to disable voice pitch modulation */

/* Note: We have the ability to replace the real death sound (33) and the
 * real voices with sample (34) as no good death sample could be obtained.
 */


/* volume and channel controls */
#define VOICE_VOLUME 100
#define SOUND_VOLUME 80
#define SOUND_CHANNEL 1    /* channel for sound effects */
#define VOICE_CHANNEL 5    /* special channel for voice sounds only */
#define DEATH_CHANNEL 6    /* special channel for fake death sound only */

/* berzerk sound */
int lastfreq = 0;
int lastnoise = 0;
int lastvoice = 0;
int lastdata = 0;

/* sound controls */
int berzerknoisemulate = 0;
int samplereset = 0;
int voicevolume = 100;
long samplefrequency = 22320;
extern int berzerkplayvoice; /* works in parallel with the read function in machine.c */
extern int collision;
int deathsound = 0;          /* trigger for playing collision sound */
int nextdata5 = -1;

int berzerk_sh_start(void)
{
	int i;


	berzerknoisemulate = 1;

	if (Machine->samples)
	{
		for (i = 0;i < 5;i++)
		{
			if (Machine->samples->sample[i])
				berzerknoisemulate = 0;
		}
	}
	return 0;
}

void berzerk_sound_control_a_w(int offset,int data)
{
	int noise = 0;
        int voice = 0;
        int voicefrequency = 0;

/* Throw out all the non-need sound info. (for the moment) */

        if (offset < 3) return;

/* Decode message for voice samples */

        if (offset==4) {
           if ((data & 0x40) == 0) {
              voice = data;
              berzerkplayvoice = 0;
           } else {
	   /* We should use the volume and frequency on the voice samples */
              voicevolume = ((data & 0x38) >> 3);
	      if (voicevolume>0) voicevolume=255;
                 voicefrequency = (data & 0x07);
#ifdef VOICE_PITCH_MODULATION
                 switch(voicefrequency) {
	            case 0 : samplefrequency = 17640;
			  break;
	            case 1 : samplefrequency = 19404;
			  break;
	            case 2 : samplefrequency = 20947;
	 		  break;
	            case 3 : samplefrequency = 22050;
			  break;
	            case 4 : samplefrequency = 26019;
			  break;
	            case 5 : samplefrequency = 27783;
			  break;
	            case 6 : samplefrequency = 31250;
			  break;
	            case 7 : samplefrequency = 34700;
			  break;
		    default: samplefrequency = 22050;
			  break;
                 }
#endif
              return;
           }
        }

/* Check for player fire sample reset */

        if ((offset==3) || (offset==5)) {
	   if (lastnoise==70) {
	      if ((offset==3) && (data==172)) {
                 nextdata5=25;
                 return;
              }
              if (offset==5)
			  {
                 if (data==nextdata5) {
#ifdef FAKE_DEATH_SOUND
                       deathsound=1; /* trigger death sound */
#else
                       deathsound=2; /* trigger death sound */
#endif
                    nextdata5=-1;
		    lastnoise=64; /* reset death sound */
                 } else
                    nextdata5=-1;
				}
              return;
           }
	   if (lastnoise==69) {
	      if ((offset==3) && (data==50)) {
                 nextdata5=50;
                 return;
              }
              if (offset==5)
			  {
                 if (data==nextdata5) {
                    lastnoise=64; /* reset laser sound */
                    nextdata5=-1;
	         } else
                    nextdata5=-1;
				}
              return;
           }
           return;
        }

/* Check to see what game sound should be playing */

	if ((data > 60) && (data < 72) && (offset==6)) {
	   noise = data;
	} else
	   noise = lastnoise;

/* One day I'll do this... */

        if (berzerknoisemulate) {
	   return;
           if (voicefrequency != 1750*(4-noise))
           {
                   voicefrequency = 1750*(4-noise);
                   voicevolume = 85*noise;
           }

           if (noise) sample_adjust(2,voicefrequency,voicevolume);
           else
           {
                   sample_adjust(2,-1,0);
                   voicevolume = 0;
           }
        } else {
	   if ((offset==6) && (lastnoise != noise))  /* Game sound effects */
              switch (noise) {
               	 case 69 : /* shot sample */
                           sample_start(1,30,0);
                	   break;
                 case 70 : /* baddie laser */
			   switch(deathsound) {
                              case 1 :
                                 sample_start(2,33,0);
			         deathsound=0;
                                 break;
                              case 2 :
                                 sample_start(DEATH_CHANNEL,34,0);
			         deathsound=3;
                                 break;
		              case 0 :
                                 sample_start(2,31,0);
                                 break;
                              }
                      	      break;
	         case 71 : /* kill baddie */
                           sample_start(3,32,0);
                	   break;
		 default :
			   break;
	      }
	      lastnoise = noise;           /* make sure we only play the sound once */
	      if (offset==4)               /* Game voice sounds */
                 if (deathsound<2) {       /* no voices for real death sound */
                    if (lastvoice==24 && voice==27) {
                       lastvoice=voice;    /* catch for the 'chicken ayye' problem */
                       return;
                     }
                       sample_start(VOICE_CHANNEL,voice,0);
#ifdef VOICE_PITCH_MODULATION
                       sample_adjust(VOICE_CHANNEL,samplefrequency,-1);
#endif
						lastvoice=voice;
                 }
        } /* End of berzerknoisemulate */
}

void berzerk_sound_control_b_w(int offset,int data)
{
}

void berzerk_sh_update(void)
{
	berzerkplayvoice = !sample_playing(VOICE_CHANNEL);
	if (deathsound==3 && sample_playing(DEATH_CHANNEL) == 0 && lastnoise != 70)
		deathsound=0;               /* reset death sound */
}