aboutsummaryrefslogtreecommitdiffstats
path: root/channels/gentone-ulaw.c
diff options
context:
space:
mode:
Diffstat (limited to 'channels/gentone-ulaw.c')
-rw-r--r--channels/gentone-ulaw.c157
1 files changed, 157 insertions, 0 deletions
diff --git a/channels/gentone-ulaw.c b/channels/gentone-ulaw.c
new file mode 100644
index 000000000..b290d76c7
--- /dev/null
+++ b/channels/gentone-ulaw.c
@@ -0,0 +1,157 @@
+/* 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;
+}
+
+/*
+** This routine converts from linear to ulaw
+**
+** Craig Reese: IDA/Supercomputing Research Center
+** Joe Campbell: Department of Defense
+** 29 September 1989
+**
+** References:
+** 1) CCITT Recommendation G.711 (very difficult to follow)
+** 2) "A New Digital Technique for Implementation of Any
+** Continuous PCM Companding Law," Villeret, Michel,
+** et al. 1973 IEEE Int. Conf. on Communications, Vol 1,
+** 1973, pg. 11.12-11.17
+** 3) MIL-STD-188-113,"Interoperability and Performance Standards
+** for Analog-to_Digital Conversion Techniques,"
+** 17 February 1987
+**
+** Input: Signed 16 bit linear sample
+** Output: 8 bit ulaw sample
+*/
+
+#define ZEROTRAP /* turn on the trap as per the MIL-STD */
+#define BIAS 0x84 /* define the add-in bias for 16 bit samples */
+#define CLIP 32635
+
+static unsigned char linear2ulaw(short sample) {
+static int exp_lut[256] = {0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
+ 4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
+ 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
+ 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
+ 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+ 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+ 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+ 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7};
+ int sign, exponent, mantissa;
+ unsigned char ulawbyte;
+
+ /* Get the sample into sign-magnitude. */
+ sign = (sample >> 8) & 0x80; /* set aside the sign */
+ if (sign != 0) sample = -sample; /* get magnitude */
+ if (sample > CLIP) sample = CLIP; /* clip the magnitude */
+
+ /* Convert from 16 bit linear to ulaw. */
+ sample = sample + BIAS;
+ exponent = exp_lut[(sample >> 7) & 0xFF];
+ mantissa = (sample >> (exponent + 3)) & 0x0F;
+ ulawbyte = ~(sign | (exponent << 4) | mantissa);
+#ifdef ZEROTRAP
+ if (ulawbyte == 0) ulawbyte = 0x02; /* optional CCITT trap */
+#endif
+
+ return(ulawbyte);
+}
+
+int main(int argc, char *argv[])
+{
+ FILE *f;
+ int freq1, freq2;
+ float wlen1, wlen2;
+ float val;
+ int x, samples1, samples2, 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 unsigned char %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, "%3d, ", (int) linear2ulaw(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;
+}