/*
 * This program reads a TCH/FS downlink capture produced with FreeCalypso tools
 * (fw version with TCH downlink sniffing feature and fc-shell tch record)
 * and converts it into our extended-libgsm binary format, to be further
 * fed to gsmfr-decode.
 */

#include <ctype.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>

main(argc, argv)
	char **argv;
{
	FILE *inf, *outf;
	char linebuf[128];
	int lineno, rc;
	uint16_t status_words[3];
	uint8_t tidsp_bytes[33], libgsm_bytes[33], bfi[2];
	unsigned fn_mod_104;

	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 (lineno = 1; fgets(linebuf, sizeof linebuf, inf); lineno++) {
		/* support both old and new formats */
		if (isxdigit(linebuf[0]) && isxdigit(linebuf[1]) &&
		    isxdigit(linebuf[2]) && isxdigit(linebuf[3])) {
			rc = parse_dlcap_common(linebuf, status_words,
						tidsp_bytes);
			if (rc < 0) {
invalid:			fprintf(stderr,
				"error: %s is not in the expected format\n",
					argv[1]);
				exit(1);
			}
			fn_mod_104 = 0;		/* won't have TAF */
		} else if (!strncmp(linebuf, "FR ", 3)) {
			rc = parse_dlcap_common(linebuf + 3, status_words,
						tidsp_bytes);
			if (rc < 0)
				goto invalid;
			if (linebuf[84] != ' ')
				goto invalid;
			if (!isdigit(linebuf[85]))
				goto invalid;
			fn_mod_104 = strtoul(linebuf + 85, 0, 10);
		} else
			goto invalid;
		/*
		 * DSP flags are documented in the TCH-tap-modes article
		 * in freecalypso-docs.
		 */
		if ((status_words[0] & 0xC004) == 0xC000) {
			gsm0610_tidsp_to_libgsm(tidsp_bytes, libgsm_bytes);
			fwrite(libgsm_bytes, 1, 33, outf);
		} else {
			bfi[0] = 0xBF;
			bfi[1] = fn_mod_104 == 60;
			fwrite(bfi, 1, 2, outf);
		}
	}
	exit(0);
}