From 488a13b110d3563194dd63e087e295a4aa114002 Mon Sep 17 00:00:00 2001 From: Uwe Hermann Date: Thu, 22 Dec 2011 14:10:16 +0100 Subject: [PATCH] Improve sr_filter_probes error handling and docs. - Much more elaborate doxygen comments for the function and its parameters, allowed input values, and so on. - Make 'probelist' const, the function doesn't modify it. - Check for invalid inputs such as NULL pointers. - Use g_try_malloc() and g_free() for the output buffer. Document who is expected to g_free() the buffer. --- filter.c | 74 +++++++++++++++++++++++++++++++++++++++++++------- sigrok-proto.h | 2 +- 2 files changed, 65 insertions(+), 11 deletions(-) diff --git a/filter.c b/filter.c index 80cef6ab..5698d333 100644 --- a/filter.c +++ b/filter.c @@ -21,6 +21,7 @@ #include #include #include +#include "sigrok-internal.h" /** * Remove unused probes from samples. @@ -29,16 +30,47 @@ * 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. + * The "unit size" is the number of bytes used to store probe values. + * For example, a unit size of 1 means one byte is used (which can store + * 8 probe values, each of them is 1 bit). A unit size of 2 means we can + * store 16 probe values, 3 means we can store 24 probe 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 probes), 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 probe values in the order specified via the + * probelist. For example, if in_unitsize = 4, probelist = [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 probe 5, bit 1 = value + * of probe 16, bit 2 = value of probe 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). + * @param probelist Pointer to a list of integers (probe numbers). The probe + * numbers in this list are 1-based, i.e. the first probe + * is expected to be numbered 1 (not 0!). Must not be NULL. + * @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. */ -int sr_filter_probes(int in_unitsize, int out_unitsize, int *probelist, +int sr_filter_probes(int in_unitsize, int out_unitsize, const int *probelist, const unsigned char *data_in, uint64_t length_in, char **data_out, uint64_t *length_out) { @@ -46,8 +78,30 @@ int sr_filter_probes(int in_unitsize, int out_unitsize, int *probelist, int num_enabled_probes, out_bit, i; uint64_t sample_in, sample_out; - if (!(*data_out = malloc(length_in))) + if (!probelist) { + sr_err("filter: %s: probelist was NULL", __func__); + return SR_ERR_ARG; + } + + if (!data_in) { + sr_err("filter: %s: data_in was NULL", __func__); + return SR_ERR_ARG; + } + + if (!data_out) { + sr_err("filter: %s: data_out was NULL", __func__); + return SR_ERR_ARG; + } + + if (!length_out) { + sr_err("filter: %s: length_out was NULL", __func__); + return SR_ERR_ARG; + } + + if (!(*data_out = g_try_malloc(length_in))) { + sr_err("filter: %s: data_out malloc failed", __func__); return SR_ERR_MALLOC; + } num_enabled_probes = 0; for (i = 0; probelist[i]; i++) diff --git a/sigrok-proto.h b/sigrok-proto.h index 728ffc73..2c3be8b1 100644 --- a/sigrok-proto.h +++ b/sigrok-proto.h @@ -60,7 +60,7 @@ gboolean sr_device_has_hwcap(struct sr_device *device, int hwcap); /*--- filter.c --------------------------------------------------------------*/ -int sr_filter_probes(int in_unitsize, int out_unitsize, int *probelist, +int sr_filter_probes(int in_unitsize, int out_unitsize, const int *probelist, const unsigned char *data_in, uint64_t length_in, char **data_out, uint64_t *length_out);