gentone.c

Asterisk中信道部分的源码 。。。。

/* Generate a header file for a particular 
   single or double frequency */

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#define CLIP 32635
#define BIAS 0x84
static float loudness=16384.0;

static int calc_samples(int freq)
{
	int x, samples;
	/* Calculate the number of samples at 8000hz sampling
	   we need to have this wave form */
	samples = 8000;
	/* Take out common 2's up to six times */
	for (x=0;x<6;x++) 
		if (!(freq % 2)) {
			freq /= 2;
			samples /= 2;
		}
	/* Take out common 5's (up to three times */
	for (x=0;x<3;x++) 
		if (!(freq % 5)) {
			freq /= 5;
			samples /=5;
		}
	/* No more common factors. */
	return samples;
}

int main(int argc, char *argv[])
{
	FILE *f;
	int freq1, freq2;
	float wlen1, wlen2;
	float val;
	int x, samples1, samples2=0, samples=0;
	char fn[256];
	if (argc < 3) {
		fprintf(stderr, "Usage: gensound <name> <freq1> [freq2]\n");
		exit(1);
	}
	freq1 = atoi(argv[2]);
	if (argc > 3) 
		freq2 = atoi(argv[3]);
	else
		freq2 = 0;
	wlen1 = 8000.0/(float)freq1;
	samples1 = calc_samples(freq1);
	printf("Wavelength 1 (in samples): %10.5f\n", wlen1);
	printf("Minimum samples (1): %d (%f.3 wavelengths)\n", samples1, samples1 / wlen1);
	if (freq2) {
		wlen2 = 8000.0/(float)freq2;
		samples2 = calc_samples(freq2);
		printf("Wavelength 1 (in samples): %10.5f\n", wlen2);
		printf("Minimum samples (1): %d (%f.3 wavelengths)\n", samples2, samples2 / wlen2);
	}
	samples = samples1;
	if (freq2) {
		while(samples % samples2)
			samples += samples1;
	}
	printf("Need %d samples\n", samples);
	snprintf(fn, sizeof(fn), "%s.h", argv[1]);
	if ((f = fopen(fn, "w"))) {
		if (freq2) 
			fprintf(f, "/* %s: Generated from frequencies %d and %d \n"
			           "   by gentone.  %d samples  */\n", fn, freq1, freq2, samples); 
		else
			fprintf(f, "/* %s: Generated from frequency %d\n"
			           "   by gentone.  %d samples  */\n", fn, freq1, samples); 
		fprintf(f, "static short %s[%d] = {\n\t", argv[1], samples);
		for (x=0;x<samples;x++) {
			val = loudness * sin((freq1 * 2.0 * M_PI * x)/8000.0);
			if (freq2)
				val += loudness * sin((freq2 * 2.0 * M_PI * x)/8000.0);
			fprintf(f, "%5d, ", (int)val);
			if (!((x+1) % 8)) 
				fprintf(f, "\n\t");
		}
		if (x % 15)
			fprintf(f, "\n");
		fprintf(f, "};\n");
		fclose(f);
		printf("Wrote %s\n", fn);
	} else {
		fprintf(stderr, "Unable to open %s for writing\n", fn);
		return 1;
	}
	return 0;
}