cassette/main.c

/*
 * main.c
 *
 * Copyright (C) 2023 bzt
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * @brief Main file for "cassette" audio-binary converter
 *
 */

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

uint8_t *decode(uint8_t *data, size_t size, int fmt, int en, int nb, int sy, int fm, int ng, int length, int hdr, int skip, size_t *outlen);
uint8_t *encode(uint8_t *data, size_t size, int fmt, int en, int nb, int sy, int fm, int ng, int length, int hdr, int rate, int ol, int zl, int bitrate, int quality, size_t *outlen);
int verbose = 0;

/**
 * Usage instructions
 */
void usage(char *cmd)
{
    printf("Cassette by bzt GPLv3+\r\nhttps://gitlab.com/bztsrc/cassette\r\n\r\n");
    printf("%s [opts|-s] <in.wav|in.mp3> <out.bin>\r\n", cmd);
    printf("%s [opts] <in.bin> <out.wav>\r\n", cmd);
    printf("%s [opts|-b|-q] <in.bin> <out.mp3>\r\n\r\n", cmd);
    printf("  -v | -vv      be verbose\r\n");
    printf("Data encoding options\r\n");
    printf("  -e            endianess, least significant bit comes first\r\n");
    printf("  -7            assume 7 bits per byte on the tape\r\n");
    printf("  -0            no sync bit (default, 0 = 0, 1 = 1)\r\n");
    printf("  -1            two bits, first is sync bit (10 = 0, 11 = 1)\r\n");
    printf("  -2            two bits, second is sync bit (01 = 0, 11 = 1)\r\n");
    printf("  -3            three bits, two sync bits (101 = 0, 111 = 1)\r\n");
    printf("  -d            FM, frequency modulated, down-edge (defaults to AM)\r\n");
    printf("  -u            FM, frequency modulated, up-edge\r\n");
    printf("  -du           FM, frequency modulated, both edges\r\n");
    printf("Sample encoding options\r\n");
    printf("  -h            do not detect but generate Homelab header\r\n");
    printf("  -s            input is signed 8-bit PCM\r\n");
    printf("  -S <n>        skip N samples at the beginning\r\n");
    printf("  -l <usec>     one bit's length in microsec (eg. 770)\r\n");
    printf("  -g <usec>     gap between bytes (AM) or diff in zero and one lengths (FM)\r\n");
    printf("  -r <rate>     sample rate (eg. 44100 or 48000)\r\n");
    printf("  -o <num>      bit set level (eg. 127)\r\n");
    printf("  -z <num>      bit clear level (eg. -32)\r\n");
    printf("MP3 encoding options\r\n");
    printf("  -b <bitrate>  bit rate (eg. 96, 128 or 192)\r\n");
    printf("  -q <quality>  quality (0 best, 9 worst)\r\n\r\n");
    printf("You should have received a copy of the GNU General Public License\r\n");
    printf("along with this program.  If not, see <http://www.gnu.org/licenses/>.\r\n\r\n");
    exit(1);
}

/**
 * Main function
 */
int main(int argc, char **argv)
{
    FILE *f;
    int i, j;
    int length = 0, en = 0, nb = 8, sy = 0, fm = 0, ng = 0, hdr = 0, skip = 0, rate = 44100, ol = 127, zl = -65536;
    int bitrate = 96, quality = 0, fmt = 0;
    char *infile = NULL, *outfile = NULL, *ext;
    uint8_t *data = NULL, *out = NULL;
    size_t size;

    /* parse command line */
    for(i = 1; i < argc; i++)
        if(argv[i][0] == '-')
            switch(argv[i][1]) {
                case 'l': length = atoi(argv[++i]); break;
                case 'g': ng = atoi(argv[++i]); break;
                case 'r': rate = atoi(argv[++i]); break;
                case 'o': ol = atoi(argv[++i]); break;
                case 'z': zl = atoi(argv[++i]); break;
                case 'b': bitrate = atoi(argv[++i]); break;
                case 'q': quality = atoi(argv[++i]); break;
                case 'S': skip = atoi(argv[++i]); break;
                default:
                    for(j = 1; argv[i][j]; j++)
                        switch(argv[i][j]) {
                            case 's': fmt = 1; break;
                            case 'd': fm |= 1; break;
                            case 'u': fm |= 2; break;
                            case 'e': en = 1; break;
                            case '7': nb = 7; break;
                            case '0': sy = 0; break;
                            case '1': sy = 1; break;
                            case '2': sy = 2; break;
                            case '3': sy = 3; break;
                            case 'h': hdr = 1; break;
                            case 'v': verbose++; break;
                            default: usage(argv[0]); break;
                        }
                break;
            }
        else
        if(!infile) infile = argv[i]; else
        if(!outfile) outfile = argv[i]; else usage(argv[0]);
    if(!infile || !outfile) usage(argv[0]);
    if(zl == -65536) zl = fm ? -127 : -64;

    /* read input file */
    f = fopen(infile, "rb");
    if(f) {
        fseek(f, 0, SEEK_END);
        size = (size_t)ftell(f);
        fseek(f, 0, SEEK_SET);
        data = (uint8_t*)malloc(size);
        if(!data) { fprintf(stderr, "cassette: unable to allocate memory\r\n"); exit(2); }
        (void)fread(data, 1, size, f);
        fclose(f);
    } else {
        fprintf(stderr, "cassette: unable to open '%s'\r\n", infile);
        exit(1);
    }

    /* do the thing */
    ext = strrchr(outfile, '.');
    if(ext && (!strcmp(ext, ".wav") || !strcmp(ext, ".mp3")))
        out = encode(data, size, ext && !strcmp(ext, ".mp3"), en, nb, sy, fm, ng, length, hdr, rate, ol, zl, bitrate, quality, &size);
    else
        out = decode(data, size, fmt, en, nb, sy, fm, ng, length, !hdr, skip, &size);
    /* write output file */
    if(size > 0 && out) {
        f = fopen(outfile, "wb");
        if(f) {
            (void)fwrite(out, 1, size, f);
            fclose(f);
        } else {
            fprintf(stderr, "cassette: unable to write '%s'\r\n", outfile);
        }
    }

    /* free resources */
    if(out) free(out);
    if(data) free(data);
    return 0;
}