/*
 * Our gsm-amr2efr utility reads in a speech recording in .amr format
 * (the mode must be MR122 for every frame, no DTX) and converts it into
 * our ad hoc .gsmx format for EFR.  The conversion is a bit reshuffling
 * only, no transcoding takes place.
 */

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

extern const uint8_t amr_122_bit_order[244];

static const char amr_file_hdr[] = "#!AMR\n";

main(argc, argv)
	char **argv;
{
	char *infname, *outfname;
	FILE *inf, *outf;
	int wrong_flag, hdrb;
	uint8_t frm_in[31], frm_out[31];
	unsigned bit_a, bit_n;

	if (argc == 3 && argv[1][0] != '-') {
		wrong_flag = 0;
		infname = argv[1];
		outfname = argv[2];
	} else if (argc == 4 && !strcmp(argv[1], "-w")) {
		wrong_flag = 1;
		infname = argv[2];
		outfname = argv[3];
	} else {
		fprintf(stderr, "usage: %s [-w] input.amr output.gsmx\n",
			argv[0]);
		exit(1);
	}
	inf = fopen(infname, "r");
	if (!inf) {
		perror(infname);
		exit(1);
	}
	if (fread(frm_in, 1, 6, inf) != 6 || bcmp(frm_in, amr_file_hdr, 6)) {
		fprintf(stderr, "error: %s is not in AMR format\n", infname);
		exit(1);
	}
	outf = fopen(outfname, "w");
	if (!outf) {
		perror(outfname);
		exit(1);
	}
	for (;;) {
		hdrb = getc(inf);
		if (hdrb < 0)
			break;
		if ((hdrb & 0x78) != 0x38) {
			fprintf(stderr, "error: unexpected content in %s\n",
				infname);
			exit(1);
		}
		if (fread(frm_in, 1, 31, inf) != 31) {
			fprintf(stderr, "error: short read from %s\n", infname);
			exit(1);
		}
		frm_out[0] = 0xC0;
		for (bit_a = 0; bit_a < 244; bit_a++) {
			if (wrong_flag)
				bit_n = bit_a;
			else
				bit_n = amr_122_bit_order[bit_a];
			msb_set_bit(frm_out, 4 + bit_n,
				    msb_get_bit(frm_in, bit_a));
		}
		fwrite(frm_out, 1, 31, outf);
	}
	fclose(outf);
	exit(0);
}