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1 | /* | |
2 | * This file is part of the sigrok project. | |
3 | * | |
4 | * Copyright (C) 2010-2012 Bert Vermeulen <bert@biot.com> | |
5 | * | |
6 | * This program is free software: you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation, either version 3 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
18 | */ | |
19 | ||
20 | #include <stdlib.h> | |
21 | #include <stdint.h> | |
22 | #include <string.h> | |
23 | #include "sigrok.h" | |
24 | #include "sigrok-internal.h" | |
25 | ||
26 | /** | |
27 | * Remove unused probes from samples. | |
28 | * | |
29 | * Convert sample from maximum probes -- the way the hardware driver sent | |
30 | * it -- to a sample taking up only as much space as required, with | |
31 | * unused probes removed. | |
32 | * | |
33 | * The "unit size" is the number of bytes used to store probe values. | |
34 | * For example, a unit size of 1 means one byte is used (which can store | |
35 | * 8 probe values, each of them is 1 bit). A unit size of 2 means we can | |
36 | * store 16 probe values, 3 means we can store 24 probe values, and so on. | |
37 | * | |
38 | * If the data coming from the logic analyzer has a unit size of 4 for | |
39 | * example (as the device has 32 probes), but only 2 of them are actually | |
40 | * used in an acquisition, this function can convert the samples to only | |
41 | * use up 1 byte per sample (unit size = 1) instead of 4 bytes per sample. | |
42 | * | |
43 | * The output will contain the probe values in the order specified via the | |
44 | * probelist. For example, if in_unitsize = 4, probelist = [5, 16, 30], and | |
45 | * out_unitsize = 1, then the output samples (each of them one byte in size) | |
46 | * will have the following format: bit 0 = value of probe 5, bit 1 = value | |
47 | * of probe 16, bit 2 = value of probe 30. Unused bit(s) in the output byte(s) | |
48 | * are zero. | |
49 | * | |
50 | * The caller must make sure that length_in is not bigger than the memory | |
51 | * actually allocated for the input data (data_in), as this function does | |
52 | * not check that. | |
53 | * | |
54 | * @param in_unitsize The unit size (>= 1) of the input (data_in). | |
55 | * @param out_unitsize The unit size (>= 1) the output shall have (data_out). | |
56 | * The requested unit size must be big enough to hold as | |
57 | * much data as is specified by the number of enabled | |
58 | * probes in 'probelist'. | |
59 | * @param probelist Pointer to a list of integers (probe numbers). The probe | |
60 | * numbers in this list are 1-based, i.e. the first probe | |
61 | * is expected to be numbered 1 (not 0!). Must not be NULL. | |
62 | * @param data_in Pointer to the input data buffer. Must not be NULL. | |
63 | * @param length_in The input data length (>= 1), in number of bytes. | |
64 | * @param data_out Variable which will point to the newly allocated buffer | |
65 | * of output data. The caller is responsible for g_free()'ing | |
66 | * the buffer when it's no longer needed. Must not be NULL. | |
67 | * @param length_out Pointer to the variable which will contain the output | |
68 | * data length (in number of bytes) when the function | |
69 | * returns SR_OK. Must not be NULL. | |
70 | * | |
71 | * @return SR_OK upon success, SR_ERR_MALLOC upon memory allocation errors, | |
72 | * or SR_ERR_ARG upon invalid arguments. | |
73 | * If something other than SR_OK is returned, the values of | |
74 | * out_unitsize, data_out, and length_out are undefined. | |
75 | */ | |
76 | SR_API int sr_filter_probes(int in_unitsize, int out_unitsize, | |
77 | const int *probelist, const unsigned char *data_in, | |
78 | uint64_t length_in, char **data_out, | |
79 | uint64_t *length_out) | |
80 | { | |
81 | unsigned int in_offset, out_offset; | |
82 | int num_enabled_probes, out_bit, i; | |
83 | uint64_t sample_in, sample_out; | |
84 | ||
85 | if (!probelist) { | |
86 | sr_err("filter: %s: probelist was NULL", __func__); | |
87 | return SR_ERR_ARG; | |
88 | } | |
89 | ||
90 | if (!data_in) { | |
91 | sr_err("filter: %s: data_in was NULL", __func__); | |
92 | return SR_ERR_ARG; | |
93 | } | |
94 | ||
95 | if (!data_out) { | |
96 | sr_err("filter: %s: data_out was NULL", __func__); | |
97 | return SR_ERR_ARG; | |
98 | } | |
99 | ||
100 | if (!length_out) { | |
101 | sr_err("filter: %s: length_out was NULL", __func__); | |
102 | return SR_ERR_ARG; | |
103 | } | |
104 | ||
105 | num_enabled_probes = 0; | |
106 | for (i = 0; probelist[i]; i++) | |
107 | num_enabled_probes++; | |
108 | ||
109 | /* Are there more probes than the target unit size supports? */ | |
110 | if (num_enabled_probes > out_unitsize * 8) { | |
111 | sr_err("filter: %s: too many probes (%d) for the target unit " | |
112 | "size (%d)", num_enabled_probes, out_unitsize, __func__); | |
113 | return SR_ERR_ARG; | |
114 | } | |
115 | ||
116 | if (!(*data_out = g_try_malloc(length_in))) { | |
117 | sr_err("filter: %s: data_out malloc failed", __func__); | |
118 | return SR_ERR_MALLOC; | |
119 | } | |
120 | ||
121 | if (num_enabled_probes == in_unitsize * 8) { | |
122 | /* All probes are used -- no need to compress anything. */ | |
123 | memcpy(*data_out, data_in, length_in); | |
124 | *length_out = length_in; | |
125 | return SR_OK; | |
126 | } | |
127 | ||
128 | /* If we reached this point, not all probes are used, so "compress". */ | |
129 | in_offset = out_offset = 0; | |
130 | while (in_offset <= length_in - in_unitsize) { | |
131 | memcpy(&sample_in, data_in + in_offset, in_unitsize); | |
132 | sample_out = out_bit = 0; | |
133 | for (i = 0; probelist[i]; i++) { | |
134 | if (sample_in & (1 << (probelist[i] - 1))) | |
135 | sample_out |= (1 << out_bit); | |
136 | out_bit++; | |
137 | } | |
138 | memcpy((*data_out) + out_offset, &sample_out, out_unitsize); | |
139 | in_offset += in_unitsize; | |
140 | out_offset += out_unitsize; | |
141 | } | |
142 | *length_out = out_offset; | |
143 | ||
144 | return SR_OK; | |
145 | } |