mirror of
https://codeberg.org/libreboot/lbmk.git
synced 2026-07-14 07:19:40 +02:00
Leah Rowe
3c2a287eea
when calling fread(), errno may be set to EOVEFLOW if the range being read will cause an integer overflow if end-of-file is reached, errno may not be set. when calling this function, you must check errno or check feof() - ferror() should also be checked, so this check is added immediately afterwards in the code ferror() does not set errno, so ERR() is used to set errno to ECANCELED as program exit status further separate reading of frames into a new function Signed-off-by: Leah Rowe <leah@libreboot.org>
141 lines
2.6 KiB
C
141 lines
2.6 KiB
C
/* spkmodem-recv.c - decode spkmodem signals */
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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#include <err.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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/* Compilation: gcc -o spkmodem-recv spkmodem-recv */
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/* Usage: parec --channels=1 --rate=48000 --format=s16le | ./spkmodem-recv */
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#define SAMPLES_PER_FRAME 240
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#define FREQ_SEP_MIN 5
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#define FREQ_SEP_MAX 15
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#define FREQ_DATA_MIN 15
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#define FREQ_DATA_THRESHOLD 25
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#define FREQ_DATA_MAX 60
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#define THRESHOLD 500
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#define DEBUG 0
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#define FLUSH_TIMEOUT 1
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#define ERR() (errno = errno ? errno : ECANCELED)
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signed short frame[2 * SAMPLES_PER_FRAME];
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signed short pulse[2 * SAMPLES_PER_FRAME];
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int f1, f2, lp, ascii_bit = 7;
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char ascii = 0;
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void handle_audio(void);
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void print_char(void);
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void fetch_sample(void);
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void read_frame(int ringpos);
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int
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main(int argc, char *argv[])
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{
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int c;
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#ifdef __OpenBSD__
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if (pledge("stdio", NULL) == -1)
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err(errno, "pledge");
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#endif
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while ((c = getopt(argc, argv, "u")) != -1) {
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switch (c) {
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case 'u':
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setvbuf(stdout, NULL, _IONBF, 0);
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break;
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default:
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err(errno = EINVAL, NULL);
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}
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}
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while (!feof(stdin))
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handle_audio();
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return errno;
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}
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void
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handle_audio(void)
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{
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static int llp = 0;
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if (lp > (3 * SAMPLES_PER_FRAME)) {
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ascii_bit = 7;
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ascii = 0;
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lp = 0;
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llp++;
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}
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if (llp == FLUSH_TIMEOUT)
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if (fflush(stdout) == EOF)
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err(errno, NULL);
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if ((f2 <= FREQ_SEP_MIN) || (f2 >= FREQ_SEP_MAX)
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|| (f1 <= FREQ_DATA_MIN) || (f1 >= FREQ_DATA_MAX)) {
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fetch_sample();
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return;
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}
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print_char();
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lp = 0;
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llp = 0;
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for (int i = 0; i < SAMPLES_PER_FRAME; i++)
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fetch_sample();
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}
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void
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fetch_sample(void)
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{
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static int ringpos = 0;
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f1 -= pulse[ringpos];
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f1 += pulse[(ringpos + SAMPLES_PER_FRAME) % (2 * SAMPLES_PER_FRAME)];
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f2 -= pulse[(ringpos + SAMPLES_PER_FRAME) % (2 * SAMPLES_PER_FRAME)];
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read_frame(ringpos);
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pulse[ringpos] = (abs(frame[ringpos]) > THRESHOLD) ? 1 : 0;
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if (pulse[ringpos++])
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++f2;
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ringpos %= 2 * SAMPLES_PER_FRAME;
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++lp;
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}
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void
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read_frame(int ringpos)
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{
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if (fread(frame + ringpos, 1, sizeof(frame[0]), stdin)
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!= sizeof(frame[0]))
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err(ERR(), "Could not read from frame.");
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if (ferror(stdin) != 0)
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err(ERR(), "Could not read from frame");
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}
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void
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print_char(void)
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{
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#if DEBUG
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long stdin_pos = 0;
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if ((stdin_pos = ftell(stdin)) == -1)
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err(errno, NULL);
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printf ("%d %d %d @%ld\n", f1, f2, FREQ_DATA_THRESHOLD,
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stdin_pos - sizeof(frame));
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#endif
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if (f1 < FREQ_DATA_THRESHOLD)
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ascii |= (1 << ascii_bit);
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ascii_bit--;
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if (ascii_bit < 0) {
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#if DEBUG
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printf("<%c, %x>", ascii, ascii);
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#else
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printf("%c", ascii);
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#endif
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ascii_bit = 7;
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ascii = 0;
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}
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}
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