/*
 * This utility converts a GSM 06.10 speech recording from the format that is
 * commonly accepted as standard in the Unix/Linux world (libgsm format) into
 * hex strings of TCH bits to be fed to the GSM 05.03 channel encoder by way
 * of a TI Calypso GSM device, a FreeCalypso GSM firmware version with the
 * TCH rerouting feature, and fc-shell's tch play command.
 */

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>

main(argc, argv)
	char **argv;
{
	FILE *inf, *outf;
	u_char libgsm_bytes[33], tidsp_bytes[33];
	int cc, i, gotsome = 0;

	if (argc != 3) {
		fprintf(stderr, "usage: %s infile outfile\n", argv[0]);
		exit(1);
	}
	inf = fopen(argv[1], "r");
	if (!inf) {
		perror(argv[1]);
		exit(1);
	}
	outf = fopen(argv[2], "w");
	if (!outf) {
		perror(argv[2]);
		exit(1);
	}
	for (;;) {
		cc = fread(libgsm_bytes, 1, 33, inf);
		if (cc < 33)
			break;
		if ((libgsm_bytes[0] & 0xF0) != 0xD0) {
invalid:		fprintf(stderr, "error: %s is not in libgsm format\n",
				argv[1]);
			exit(1);
		}
		gsm0610_libgsm_to_tidsp(libgsm_bytes, tidsp_bytes);
		for (i = 0; i < 33; i++)
			fprintf(outf, "%02X", tidsp_bytes[i]);
		putc('\n', outf);
		gotsome = 1;
	}
	fclose(outf);
	if (cc) {
		if (gotsome)
			fprintf(stderr,
			"warning: extra non-33 bytes at the end of %s\n",
				argv[1]);
		else
			goto invalid;
	}
	exit(0);
}