mirror of
https://codeberg.org/libreboot/lbmk.git
synced 2026-07-11 05:52:36 +02:00
Leah Rowe
17cd0af9c1
the loop in main() already checks EOF, and errno is properly handled at the end of main() we only need to call ferror(), to check error state this fixes a bogus error message when pressing ctrl+D to terminate the program, *which is the intended way to terminate this program* (that, or EOF is reached in any other another way) do not treat intended behaviour as an error condition! Signed-off-by: Leah Rowe <leah@libreboot.org>
137 lines
3.3 KiB
C
137 lines
3.3 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: cc -o spkmodem-recv spkmodem-recv.c */
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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 MAX_SAMPLES (2 * SAMPLES_PER_FRAME)
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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[MAX_SAMPLES], pulse[MAX_SAMPLES];
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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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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 (!(debug = (c == 'd')))
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err(errno = EINVAL, NULL);
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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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int next_ringpos = (ringpos + SAMPLES_PER_FRAME) % MAX_SAMPLES;
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freq_data -= pulse[ringpos];
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freq_data += pulse[next_ringpos];
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freq_separator -= pulse[next_ringpos];
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fread(frame + ringpos, 1, sizeof(frame[0]), stdin);
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if (ferror(stdin) != 0)
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err(ERR(), "Could not read from 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 %= MAX_SAMPLES;
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++sample_count;
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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;
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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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