Hallo, AlgoMantra hat gesagt: // AlgoMantra wrote: Whoo, that text is from 2000, when Bill Clinton was president. A lot has changed since then. Ciao -- Frank Barknecht _ ______footils.org__

On Sun, 2008-06-15 at 09:38 +0530, AlgoMantra wrote: Uhmm ... But if you want to do raw sinewaves big time, you'll really need another approach if you are not to run out of CPU. That piece of code you linked to is in desperate need of an update, so that it will auto-vectorize and so that we can get rid of the expensive call to sin(). The following should do just about the same but without mathlib and generally accellerated by some insane percentage: -8<-- sound.c ----------------------------------------------------------- // Compile with for example // gcc4.3 -O3 -msse -ftree-vectorize -o sound sound.c #include <unistd.h> #include <sys/ioctl.h> #include <linux/soundcard.h> #define PI 3.14159f /* Inverse of the odd factorials (n!) 1 - 9 */ #define IF_1 (1.f) #define IF_3 (1.f/6.f) #define IF_5 (1.f/120.f) #define IF_7 (1.f/5040.f) #define IF_9 (1.f/362880.f) /* ------------------------------------- * 16 bit Taylor approximation of sin() * ------------------------------------ */ float tsin(float x) { float x2 = x*x; float rt = IF_9; rt *= x2; rt -= IF_7; rt *= x2; rt += IF_5; rt *= x2; rt -= IF_3; rt *= x2; rt += IF_1; rt *= x; return rt; } int main(void) { unsigned short int wave[44100*5]; /* our wavetable */ int i,j; /* two counters */ int out; /* audio out */ /* open /dev/dsp for write only */ out = open("/dev/dsp",O_WRONLY); /* now we use ioctl to set audio quality */ i=16; /* 16 bits */ ioctl(out,SOUND_PCM_WRITE_BITS,&i); i=1; /* 1 channel */ ioctl(out,SOUND_PCM_WRITE_CHANNELS,&i); i=44100; /* 44.1KHz */ ioctl(out,SOUND_PCM_WRITE_RATE,&i); #define OSC 4 float x[OSC] = {0,0,0,0}; float y[OSC] = {1,1,1,1}; float w[OSC] = {220, 277,330,440}; float a[OSC] = {8000,7000,6000,5000}; float r[OSC]; for (i = 0; i < OSC;++i) w[i] = tsin(w[i]*2*PI/44100); for(i = 0;i < (44100*5); ++i) { for(j=0;j < OSC; ++j) { x[j] -= w[j] * y[j]; y[j] += w[j] * x[j]; r[j] = x[j] * a[j]; } wave[i] = r[0] + r[1] + r[2] + r[3]; } /* now we write the wavetable to /dev/dsp * as though writing to a simple file * we'll loop for 5 seconds of sheer joy */ write(out, wave, sizeof(wave)); close(out); /* close /dev/dsp ! */ return 0; /* satisfy gcc */ }