播放WAV文件的c程序

#include "alloc.h" #include "dos.h" #include "conio.h" #include "stdio.h" void playwav(char wavefile[14],float delaytime); struct wavedata {   unsigned int soundlength, frequency;   char *sample; }; struct headertype {   long         riff;      //riff header   char         ni1 [18];  //not important   unsigned int channels;  //channels 1 = mono; 2 = stereo   long         frequency; //sample frequency   char         ni2 [6];   //not important   char         bitres;    //bit resolution 8/16 bit   char         ni3 [12];  //not important } header; struct wavedata voice;         //pointer to wave file unsigned int    base;          //sound blaster base address char            wavefile [25]; //file name for the wave file to be played /**************************************************************************** ** checks to see if a sound blaster exists at a given address, returns     ** ** true if sound blaster found, false if not.                              ** ****************************************************************************/ int resetdsp(unsigned int test) {   //reset the dsp   outportb (test + 0x6, 1);   delay(10);   outportb (test + 0x6, 0);   delay(10);   //check if (reset was succesfull   if ((inportb(test + 0xe) & 0x80 == 0x80) && (inportb(test + 0xa) == 0xaa))   {     //dsp was found     base = test;     return (1);   }   else     //no dsp was found     return (0); } /**************************************************************************** ** send a byte to the dsp (digital signal processor) on the sound blaster  ** ****************************************************************************/ void writedsp(unsigned char value) {   //wait for the dsp to be ready to accept data   while ((inportb(base + 0xc) & 0x80) == 0x80);   //send byte   outportb (base + 0xc, value); } /**************************************************************************** ** plays a part of the memory                                              ** ****************************************************************************/ void playback (struct wavedata *wave) {   long          linearaddress;   unsigned int  page, offset;   unsigned char timeconstant;   timeconstant = (65536 - (256000000 / wave->frequency)) >> 8;   writedsp(0x40);                  //dsp-command 40h - set sample frequency   writedsp(timeconstant);          //write time constant   //convert pointer to linear address   linearaddress = fp_seg (wave->sample);   linearaddress = (linearaddress << 4) + fp_off (wave->sample);   page = linearaddress >> 16;      //calculate page   offset = linearaddress & 0xffff; //calculate offset in the page   /*       note - this procedure only works with dma channel 1   */   outportb (0x0a, 5);              //mask dma channel 1   outportb (0x0c, 0);              //clear byte pointer   outportb (0x0b, 0x49);           //set mode   /*       the mode consists of the following:       0x49 = binary 01 00 10 01                     |  |  |  |                     |  |  |  +- dma channel 01                     |  |  +---- read operation (the dsp reads from memory)                     |  +------- single cycle mode                     +---------- block mode   */   outportb (0x02, offset & 0x100); //write the offset to the dma controller   outportb (0x02, offset >> 8);   outportb (0x83, page);           //write the page to the dma controller   outportb (0x03, wave->soundlength & 0x100);   outportb (0x03, wave->soundlength >> 8);   outportb (0x0a, 1);              //unmask dma channel   writedsp(0x14);                  // dsp-command 14h - single cycle playback   writedsp(wave->soundlength & 0xff);   writedsp(wave->soundlength >> 8); } /**************************************************************************** ** loads a wave file into memory.                                          ** ** this procedure expects a _very_ standard wave header.                   ** ** it doesn't perform much error checking.                                 ** ****************************************************************************/ int loadvoice (struct wavedata *voice, char *filename) {   file *wavfile;   //if it can't be opened...   wavfile = fopen(filename, "rb");   if (wavfile == null) {     //..display error message     return (0);   }   //return length of file for sound length minus 48 bytes for .wav header   fseek(wavfile, 0l, seek_end);   voice->soundlength = ftell (wavfile) - 48;   fseek(wavfile, 0l, seek_set);   //check riff header   if (voice->soundlength > 32000) {     if (voice->soundlength > 64000) {       voice->soundlength = 64000;     }   }   free(voice->sample);   voice->sample = (char *)malloc(voice->soundlength); //assign memory   if (!voice->sample) {           return (0);   }   //load the sample data   fread(&header, 46, 1, wavfile);   //check riff header   if (header.riff != 0x46464952) {     printf ("not a wave file\n");     return (0);   }   //check channels   if (header.channels != 1) {     printf ("not a mono wave file\n");     return (0);   }   //check bit resolution   if (header.bitres != 8) {     printf ("not an 8-bit wave file\n");     return (0);   }   voice->frequency = header.frequency;   //load the sample data   fread(voice->sample, voice->soundlength + 2, 1, wavfile);   fclose (wavfile); //close the file   return (1); } void playwav (char wavefile[14], float delaytime = 1.0 ) {   if (resetdsp (0x220)) {     //at 220h     printf ("");   } else {     if (resetdsp (0x240)) {       //at 240h       printf ("");     } else {       //or none at all       printf ("");       return;     }   }   //load wave file   if (loadvoice (&voice, wavefile)) {     //start playback     playback (&voice);     delay(delaytime*1000);     //stops dma-transfer     writedsp (0xd0);   } }