/*
- * This file is part of the sigrok project.
+ * This file is part of the libsigrok project.
*
- * Copyright (C) 2010 Bert Vermeulen <bert@biot.com>
+ * Copyright (C) 2010-2012 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
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
-#include <sigrok.h>
+#include <glib.h>
+#include "libsigrok.h"
+#include "libsigrok-internal.h"
-/*
- * Convert sample from maximum probes -- the way the hardware driver sent
+#define LOG_PREFIX "filter"
+
+/**
+ * @file
+ *
+ * Helper functions to filter out unused channels from samples.
+ */
+
+/**
+ * @defgroup grp_filter Channel filter
+ *
+ * Helper functions to filter out unused channels from samples.
+ *
+ * @{
+ */
+
+/**
+ * Remove unused channels from samples.
+ *
+ * Convert sample from maximum channels -- the way the hardware driver sent
* it -- to a sample taking up only as much space as required, with
- * unused probes removed.
+ * unused channels removed.
+ *
+ * The "unit size" is the number of bytes used to store channel values.
+ * For example, a unit size of 1 means one byte is used (which can store
+ * 8 channel values, each of them is 1 bit). A unit size of 2 means we can
+ * store 16 channel values, 3 means we can store 24 channel values, and so on.
+ *
+ * If the data coming from the logic analyzer has a unit size of 4 for
+ * example (as the device has 32 channels), but only 2 of them are actually
+ * used in an acquisition, this function can convert the samples to only
+ * use up 1 byte per sample (unit size = 1) instead of 4 bytes per sample.
+ *
+ * The output will contain the channel values in the order specified via the
+ * channellist. For example, if in_unitsize = 4, channellist = [5, 16, 30], and
+ * out_unitsize = 1, then the output samples (each of them one byte in size)
+ * will have the following format: bit 0 = value of channel 5, bit 1 = value
+ * of channel 16, bit 2 = value of channel 30. Unused bit(s) in the output byte(s)
+ * are zero.
+ *
+ * The caller must make sure that length_in is not bigger than the memory
+ * actually allocated for the input data (data_in), as this function does
+ * not check that.
+ *
+ * @param in_unitsize The unit size (>= 1) of the input (data_in).
+ * @param out_unitsize The unit size (>= 1) the output shall have (data_out).
+ * The requested unit size must be big enough to hold as
+ * much data as is specified by the number of enabled
+ * channels in 'channellist'.
+ * @param channel_array Pointer to a list of channel numbers, numbered starting
+ * from 0. The list is terminated with -1.
+ * @param data_in Pointer to the input data buffer. Must not be NULL.
+ * @param length_in The input data length (>= 1), in number of bytes.
+ * @param data_out Variable which will point to the newly allocated buffer
+ * of output data. The caller is responsible for g_free()'ing
+ * the buffer when it's no longer needed. Must not be NULL.
+ * @param length_out Pointer to the variable which will contain the output
+ * data length (in number of bytes) when the function
+ * returns SR_OK. Must not be NULL.
+ *
+ * @return SR_OK upon success, SR_ERR_MALLOC upon memory allocation errors,
+ * or SR_ERR_ARG upon invalid arguments.
+ * If something other than SR_OK is returned, the values of
+ * out_unitsize, data_out, and length_out are undefined.
+ *
+ * @since 0.2.0
*/
-int filter_probes(int in_unitsize, int out_unitsize, int *probelist,
- char *data_in, uint64_t length_in, char **data_out,
- uint64_t * length_out)
+SR_API int sr_filter_channels(unsigned int in_unitsize, unsigned int out_unitsize,
+ const GArray *channel_array, const uint8_t *data_in,
+ uint64_t length_in, uint8_t **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;
+ int *channellist, out_bit;
+ unsigned int i;
+ uint8_t *sample_in, *sample_out;
- *data_out = malloc(length_in);
- num_enabled_probes = 0;
- for (i = 0; probelist[i]; i++)
- num_enabled_probes++;
+ if (!channel_array) {
+ sr_err("%s: channel_array was NULL", __func__);
+ return SR_ERR_ARG;
+ }
+ channellist = (int *)channel_array->data;
- if (num_enabled_probes != in_unitsize * 8) {
- in_offset = out_offset = 0;
- while (in_offset <= length_in - in_unitsize) {
- memcpy(&sample_in, data_in + in_offset, in_unitsize);
- sample_out = 0;
- 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;
- } else {
- /* All probes are used -- no need to compress anything. */
+ if (!data_in) {
+ sr_err("%s: data_in was NULL", __func__);
+ return SR_ERR_ARG;
+ }
+
+ if (!data_out) {
+ sr_err("%s: data_out was NULL", __func__);
+ return SR_ERR_ARG;
+ }
+
+ if (!length_out) {
+ sr_err("%s: length_out was NULL", __func__);
+ return SR_ERR_ARG;
+ }
+
+ /* Are there more channels than the target unit size supports? */
+ if (channel_array->len > out_unitsize * 8) {
+ sr_err("%s: too many channels (%d) for the target unit "
+ "size (%d)", __func__, channel_array->len, out_unitsize);
+ return SR_ERR_ARG;
+ }
+
+ if (!(*data_out = g_try_malloc(length_in))) {
+ sr_err("%s: data_out malloc failed", __func__);
+ return SR_ERR_MALLOC;
+ }
+
+ if (channel_array->len == in_unitsize * 8) {
+ /* All channels are used -- no need to compress anything. */
memcpy(*data_out, data_in, length_in);
*length_out = length_in;
+ return SR_OK;
}
- return SIGROK_OK;
+ /* If we reached this point, not all channels are used, so "compress". */
+ in_offset = out_offset = 0;
+ while (in_offset <= length_in - in_unitsize) {
+ sample_in = (uint8_t *)data_in + in_offset;
+ sample_out = (*data_out) + out_offset;
+ memset(sample_out, 0, out_unitsize);
+ out_bit = 0;
+ for (i = 0; i < channel_array->len; i++) {
+ if (sample_in[channellist[i]>>3] & (1 << (channellist[i]&7)))
+ sample_out[out_bit>>3] |= (1 << (out_bit&7));
+ out_bit++;
+ }
+ in_offset += in_unitsize;
+ out_offset += out_unitsize;
+ }
+ *length_out = out_offset;
+
+ return SR_OK;
}
+
+/** @} */
projects / libsigrok.git / blobdiff