libsigrok/filter.c

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/*
* This file is part of the sigrok project.
*
* Copyright (C) 2010 Bert Vermeulen <bert@biot.com>
*
* 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, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
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#include <sigrok.h>
/**
* Remove unused probes from samples.
*
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* Convert sample from maximum probes -- the way the hardware driver sent
* it -- to a sample taking up only as much space as required, with
* unused probes removed.
*
* @param in_unitsize The unit size of the input (data_in).
* @param out_unitsize The unit size of the output (data_out).
* @param probelist Pointer to a list of integers (probe numbers).
* @param data_in The input data.
* @param length_in The input data length.
* @param data_out The output data.
* @param length_out The output data length.
* @return SR_OK upon success, SR_ERR_MALLOC upon memory allocation errors.
*/
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int sr_filter_probes(int in_unitsize, int out_unitsize, int *probelist,
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const unsigned char *data_in, uint64_t length_in,
char **data_out, uint64_t *length_out)
{
unsigned int in_offset, out_offset;
int num_enabled_probes, out_bit, i;
uint64_t sample_in, sample_out;
if (!(*data_out = malloc(length_in)))
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return SR_ERR_MALLOC;
num_enabled_probes = 0;
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for (i = 0; probelist[i]; i++)
num_enabled_probes++;
if (num_enabled_probes == in_unitsize * 8) {
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/* All probes are used -- no need to compress anything. */
memcpy(*data_out, data_in, length_in);
*length_out = length_in;
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return SR_OK;
}
/* If we reached this point, not all probes are used, so "compress". */
in_offset = out_offset = 0;
while (in_offset <= length_in - in_unitsize) {
memcpy(&sample_in, data_in + in_offset, in_unitsize);
sample_out = out_bit = 0;
for (i = 0; probelist[i]; i++) {
if (sample_in & (1 << (probelist[i] - 1)))
sample_out |= (1 << out_bit);
out_bit++;
}
memcpy((*data_out) + out_offset, &sample_out, out_unitsize);
in_offset += in_unitsize;
out_offset += out_unitsize;
}
*length_out = out_offset;
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return SR_OK;
}