پخش فایل WAV. با استفاده از DMA ( برای محیط MS-DOS ):
/************************************************** **************************
** WARNING: You need a HUGE memory model to run this. **
************************************************** **************************/
//Include files
#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);
}
}
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