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util/spkmodem-recv: cleaner ring buffer handling 

make it more obvious that this *is* a ring buffer being
handled, and make it more obvious when checking a pulse
in the next frame

Signed-off-by: Leah Rowe <leah@libreboot.org>
This commit is contained in:
Leah Rowe 2023-06-13 20:47:17 +01:00
parent f257eb6f9d
commit 5c5c1c64fd
1 changed files with 6 additions and 6 deletions
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12
util/spkmodem_recv/spkmodem-recv.c
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@ -27,6 +27,7 @@
/* Usage: parec --channels=1 --rate=48000 --format=s16le | ./spkmodem-recv */
#define SAMPLES_PER_FRAME 240
#define MAX_SAMPLES (2 * SAMPLES_PER_FRAME)
#define FREQ_SEP_MIN 5
#define FREQ_SEP_MAX 15
#define FREQ_DATA_MIN 15
@ -37,7 +38,7 @@
#define ERR() (errno = errno ? errno : ECANCELED)
#define reset_char() ascii = 0, ascii_bit = 7
signed short frame[2 * SAMPLES_PER_FRAME], pulse[2 * SAMPLES_PER_FRAME];
signed short frame[MAX_SAMPLES], pulse[MAX_SAMPLES];
int ringpos, debug, freq_data, freq_separator, sample_count, ascii_bit = 7;
char ascii = 0;
@ -90,17 +91,16 @@ handle_audio(void)
void
fetch_sample(void)
{
int next_ringpos = (ringpos + SAMPLES_PER_FRAME) % MAX_SAMPLES;
freq_data -= pulse[ringpos];
freq_data += pulse[(ringpos + SAMPLES_PER_FRAME)
% (2 * SAMPLES_PER_FRAME)];
freq_separator -= pulse[(ringpos + SAMPLES_PER_FRAME)
% (2 * SAMPLES_PER_FRAME)];
freq_data += pulse[next_ringpos];
freq_separator -= pulse[next_ringpos];
read_frame();
if ((pulse[ringpos] = (abs(frame[ringpos]) > THRESHOLD) ? 1 : 0))
++freq_separator;
++ringpos;
ringpos %= 2 * SAMPLES_PER_FRAME;
ringpos %= MAX_SAMPLES;
++sample_count;
}