Category : C Source Code
Archive : SBDAC.ZIP
Filename : DACDMA.C
Output of file : DACDMA.C contained in archive : SBDAC.ZIP
#include
#include
#include
#include
#include
#include
#include
#include
#include "sb.h"
void far interrupt (*OldIRQ)();
volatile int DMA_complete;
/* Interrupt handler for DMA complete IRQ from Soundblaster */
void far interrupt SBHandler()
{
enable();
DMA_complete = 1;
outportb(0x20,0x20);
}
/* Sets the sample rate to be used for digitising or playback */
void SetSampleRate(unsigned rate)
{
unsigned char tc;
tc = (unsigned char)(256 - (1000000/rate));
writedac(0x40); /* Command byte for sample rate */
writedac(tc); /* Sample rate time constant */
}
void SetVoice(int state)
{
writedac((state) ? 0xd1 : 0xd3); /* Command bytes for voice: */
/* 0xD1 - voice on */
/* 0xD3 - voice off */
}
void OutVoice(char *data, unsigned dlen)
{
int t;
long addr;
register int i;
unsigned char im, tm;
DMA_complete = 0;
/* Enable interrupts on PIC */
im = inportb(0x21);
tm = ~(1 << SbIRQ);
outportb(0x21,im & tm);
enable();
/* Set DMA mode */
outportb(DMA_MASK,5);
outportb(DMA_FF,0);
outportb(DMA_MODE,0x49);
/* Set transfer address */
addr = ((long)FP_SEG(data) << 4) + (long)FP_OFF(data);
t = (int)(addr >> 16);
outportb(DMAPAGE+3,t);
t = (int)(addr & 0xffff);
outportb(DMA + 2 * SbDMAchan,t & 0xff);
outportb(DMA + 2 * SbDMAchan,t >> 8);
/* Set transfer length byte count */
outportb(DMA + 2 * SbDMAchan + 1,dlen & 0xff);
outportb(DMA + 2 * SbDMAchan + 1,dlen >> 8);
/* Unmask DMA channel */
outportb(DMA_MASK,SbDMAchan);
/* Setup Soundblaster for transfer */
writedac(0x48); /* One command byte used for DMA DAC transfer */
/* Write length */
writedac(dlen & 0xff);
writedac(dlen >> 8);
writedac(0x14); /* Second command byte for DMA DAC transfer */
/* Write length */
writedac(dlen & 0xff);
writedac(dlen >> 8);
}
void main(int argc, char *argv[])
{
FILE *f;
char *raw;
long sample_len;
register int j, i;
unsigned sl, tmp, nr, sr;
unsigned char tm;
if(argc < 2)
{
puts("Usage: dacdma sample [sample rate]");
exit(1);
}
if(GetSBParams(&SbIOaddr,&SbIRQ,&SbDMAchan))
{
puts("BLASTER environment variable not set.");
exit(1);
}
if(InitSB())
{
printf("Could not find Soundblaster!\n");
exit(1);
}
printf("Found Soundblaster at address %xh, IRQ %d, DMA %d.\n",
SbIOaddr,SbIRQ,SbDMAchan);
f = fopen(argv[1],"rb");
if(f == NULL)
{
printf("Could not open sample file %s\n",argv[1]);
exit(1);
}
sample_len = filelength(fileno(f));
if(sample_len > 64000)
sl = 64000;
else
sl = (int)sample_len;
raw = (signed char *)farmalloc((unsigned long)sl);
nr = fread(raw,1,sl,f);
fclose(f);
/* Insert our IRQ handler into interrupt chain */
disable();
OldIRQ = getvect(0x08 + SbIRQ);
setvect(0x08 + SbIRQ,SBHandler);
enable();
sr = 11000;
if(argc == 3)
sr = atoi(argv[2]);
printf("Playing sample\n");
SetSampleRate(sr);
SetVoice(1);
OutVoice(raw,sl);
while(!kbhit() && !DMA_complete)
;
if(!DMA_complete)
getch();
SetVoice(0);
printf("Done.\n");
/* Restore old IRQ vector */
disable();
setvect(0x08 + SbIRQ,OldIRQ);
tm = inportb(0x21);
outportb(0x21,tm | (1 << SbIRQ));
enable();
farfree(raw);
exit(0);
}
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