mirror of
https://codeberg.org/libreboot/lbmk.git
synced 2026-07-14 07:19:40 +02:00
Leah Rowe
b52a7f4f86
i forked spkmodem-recv from coreboot, who forked it from gnu grub. gnu grub's version has the full header, with copyright declared as belonging to the fsf coreboot made changes after forking it, and later replaced the license declaration with an equivalent SPDX header, but they also removed the FSF's copyright declaration, which by itself does not void the declaration anyway, i just feel better re-adding the full declaration. make it so! Signed-off-by: Leah Rowe <leah@libreboot.org>
145 lines
3.4 KiB
C
145 lines
3.4 KiB
C
/* spkmodem-recv.c - decode spkmodem signals */
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/*
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* Copyright (C) 2013 Free Software Foundation, Inc.
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*
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* spkmodem-recv is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* spkmodem-recv is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with spkmodem-recv. If not, see <http://www.gnu.org/licenses/>.
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*/
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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 ERR() (errno = errno ? errno : ECANCELED)
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#define reset_char() ascii = 0, ascii_bit = 7
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signed short frame[2 * SAMPLES_PER_FRAME], pulse[2 * SAMPLES_PER_FRAME];
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int ringpos, debug, freq_data, freq_separator, sample_count, ascii_bit = 7;
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char ascii = 0;
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void handle_audio(void);
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void fetch_sample(void);
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void read_frame(void);
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int set_ascii_bit(void);
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void print_char(void);
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void print_stats(void);
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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(ERR(), "pledge");
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#endif
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while ((c = getopt(argc, argv, "d")) != -1) {
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if (c != 'd')
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err(errno = EINVAL, NULL);
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debug = 1;
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}
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setvbuf(stdout, NULL, _IONBF, 0);
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while (!feof(stdin))
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handle_audio();
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if (errno && debug)
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err(errno, "Unhandled error, errno %d", errno);
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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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if (sample_count > (3 * SAMPLES_PER_FRAME))
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sample_count = reset_char();
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if ((freq_separator <= FREQ_SEP_MIN) || (freq_separator >= FREQ_SEP_MAX)
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|| (freq_data <= FREQ_DATA_MIN) || (freq_data >= FREQ_DATA_MAX)) {
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fetch_sample();
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return;
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}
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if (set_ascii_bit() < 0)
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print_char();
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sample_count = 0;
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for (int sample = 0; sample < SAMPLES_PER_FRAME; sample++)
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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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freq_data -= pulse[ringpos];
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freq_data += pulse[(ringpos + SAMPLES_PER_FRAME)
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% (2 * SAMPLES_PER_FRAME)];
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freq_separator -= pulse[(ringpos + SAMPLES_PER_FRAME)
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% (2 * SAMPLES_PER_FRAME)];
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read_frame();
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if ((pulse[ringpos] = (abs(frame[ringpos]) > THRESHOLD) ? 1 : 0))
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++freq_separator;
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++ringpos;
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ringpos %= 2 * SAMPLES_PER_FRAME;
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++sample_count;
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}
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void
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read_frame(void)
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{
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if ((fread(frame + ringpos, 1, sizeof(frame[0]), stdin)
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!= sizeof(frame[0])) || (ferror(stdin) != 0))
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err(ERR(), "Could not read from frame.");
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}
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int
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set_ascii_bit(void)
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{
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if (debug)
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print_stats();
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if (freq_data < FREQ_DATA_THRESHOLD)
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ascii |= (1 << ascii_bit);
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--ascii_bit;
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return ascii_bit;
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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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printf("<%c, %x>", ascii, ascii);
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else
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printf("%c", ascii);
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reset_char();
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}
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void
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print_stats(void)
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{
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long stdin_pos = 0;
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if ((stdin_pos = ftell(stdin)) == -1)
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err(ERR(), NULL);
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printf ("%d %d %d @%ld\n", freq_data, freq_separator,
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FREQ_DATA_THRESHOLD, stdin_pos - sizeof(frame));
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}
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