libsigrok
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00001 /* 00002 * This file is part of the sigrok project. 00003 * 00004 * Copyright (C) 2010-2012 Bert Vermeulen <bert@biot.com> 00005 * 00006 * This program is free software: you can redistribute it and/or modify 00007 * it under the terms of the GNU General Public License as published by 00008 * the Free Software Foundation, either version 3 of the License, or 00009 * (at your option) any later version. 00010 * 00011 * This program is distributed in the hope that it will be useful, 00012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 * GNU General Public License for more details. 00015 * 00016 * You should have received a copy of the GNU General Public License 00017 * along with this program. If not, see <http://www.gnu.org/licenses/>. 00018 */ 00019 00020 #include <stdlib.h> 00021 #include <stdint.h> 00022 #include <string.h> 00023 #include "sigrok.h" 00024 #include "sigrok-internal.h" 00025 00026 /** 00027 * Remove unused probes from samples. 00028 * 00029 * Convert sample from maximum probes -- the way the hardware driver sent 00030 * it -- to a sample taking up only as much space as required, with 00031 * unused probes removed. 00032 * 00033 * The "unit size" is the number of bytes used to store probe values. 00034 * For example, a unit size of 1 means one byte is used (which can store 00035 * 8 probe values, each of them is 1 bit). A unit size of 2 means we can 00036 * store 16 probe values, 3 means we can store 24 probe values, and so on. 00037 * 00038 * If the data coming from the logic analyzer has a unit size of 4 for 00039 * example (as the device has 32 probes), but only 2 of them are actually 00040 * used in an acquisition, this function can convert the samples to only 00041 * use up 1 byte per sample (unit size = 1) instead of 4 bytes per sample. 00042 * 00043 * The output will contain the probe values in the order specified via the 00044 * probelist. For example, if in_unitsize = 4, probelist = [5, 16, 30], and 00045 * out_unitsize = 1, then the output samples (each of them one byte in size) 00046 * will have the following format: bit 0 = value of probe 5, bit 1 = value 00047 * of probe 16, bit 2 = value of probe 30. Unused bit(s) in the output byte(s) 00048 * are zero. 00049 * 00050 * The caller must make sure that length_in is not bigger than the memory 00051 * actually allocated for the input data (data_in), as this function does 00052 * not check that. 00053 * 00054 * @param in_unitsize The unit size (>= 1) of the input (data_in). 00055 * @param out_unitsize The unit size (>= 1) the output shall have (data_out). 00056 * The requested unit size must be big enough to hold as 00057 * much data as is specified by the number of enabled 00058 * probes in 'probelist'. 00059 * @param probelist Pointer to a list of integers (probe numbers). The probe 00060 * numbers in this list are 1-based, i.e. the first probe 00061 * is expected to be numbered 1 (not 0!). Must not be NULL. 00062 * @param data_in Pointer to the input data buffer. Must not be NULL. 00063 * @param length_in The input data length (>= 1), in number of bytes. 00064 * @param data_out Variable which will point to the newly allocated buffer 00065 * of output data. The caller is responsible for g_free()'ing 00066 * the buffer when it's no longer needed. Must not be NULL. 00067 * @param length_out Pointer to the variable which will contain the output 00068 * data length (in number of bytes) when the function 00069 * returns SR_OK. Must not be NULL. 00070 * 00071 * @return SR_OK upon success, SR_ERR_MALLOC upon memory allocation errors, 00072 * or SR_ERR_ARG upon invalid arguments. 00073 * If something other than SR_OK is returned, the values of 00074 * out_unitsize, data_out, and length_out are undefined. 00075 */ 00076 SR_API int sr_filter_probes(int in_unitsize, int out_unitsize, 00077 const int *probelist, const uint8_t *data_in, 00078 uint64_t length_in, uint8_t **data_out, 00079 uint64_t *length_out) 00080 { 00081 unsigned int in_offset, out_offset; 00082 int num_enabled_probes, out_bit, i; 00083 uint64_t sample_in, sample_out; 00084 00085 if (!probelist) { 00086 sr_err("filter: %s: probelist was NULL", __func__); 00087 return SR_ERR_ARG; 00088 } 00089 00090 if (!data_in) { 00091 sr_err("filter: %s: data_in was NULL", __func__); 00092 return SR_ERR_ARG; 00093 } 00094 00095 if (!data_out) { 00096 sr_err("filter: %s: data_out was NULL", __func__); 00097 return SR_ERR_ARG; 00098 } 00099 00100 if (!length_out) { 00101 sr_err("filter: %s: length_out was NULL", __func__); 00102 return SR_ERR_ARG; 00103 } 00104 00105 num_enabled_probes = 0; 00106 for (i = 0; probelist[i]; i++) 00107 num_enabled_probes++; 00108 00109 /* Are there more probes than the target unit size supports? */ 00110 if (num_enabled_probes > out_unitsize * 8) { 00111 sr_err("filter: %s: too many probes (%d) for the target unit " 00112 "size (%d)", num_enabled_probes, out_unitsize, __func__); 00113 return SR_ERR_ARG; 00114 } 00115 00116 if (!(*data_out = g_try_malloc(length_in))) { 00117 sr_err("filter: %s: data_out malloc failed", __func__); 00118 return SR_ERR_MALLOC; 00119 } 00120 00121 if (num_enabled_probes == in_unitsize * 8) { 00122 /* All probes are used -- no need to compress anything. */ 00123 memcpy(*data_out, data_in, length_in); 00124 *length_out = length_in; 00125 return SR_OK; 00126 } 00127 00128 /* If we reached this point, not all probes are used, so "compress". */ 00129 in_offset = out_offset = 0; 00130 while (in_offset <= length_in - in_unitsize) { 00131 memcpy(&sample_in, data_in + in_offset, in_unitsize); 00132 sample_out = out_bit = 0; 00133 for (i = 0; probelist[i]; i++) { 00134 if (sample_in & (1 << (probelist[i] - 1))) 00135 sample_out |= (1 << out_bit); 00136 out_bit++; 00137 } 00138 memcpy((*data_out) + out_offset, &sample_out, out_unitsize); 00139 in_offset += in_unitsize; 00140 out_offset += out_unitsize; 00141 } 00142 *length_out = out_offset; 00143 00144 return SR_OK; 00145 }