1 /*
2 * Copyright 2016 CodiLime
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 *
16 */
17 #include "data/repack.h"
18
19 #include <cstdlib>
20
21 #include "util/math.h"
22
23 using veles::util::math::gcd;
24
25 namespace veles {
26 namespace data {
27
repackUnit() const28 unsigned Repacker::repackUnit() const {
29 unsigned res = paddedWidth() / gcd(paddedWidth(), from_width) * from_width;
30 // Ensure no overflow.
31 assert(res % paddedWidth() == 0 && res % from_width == 0);
32 return res;
33 }
34
repackSize(size_t num_elements) const35 size_t Repacker::repackSize(size_t num_elements) const {
36 size_t bits = num_elements * paddedWidth();
37 assert(bits / paddedWidth() == num_elements);
38 return (bits + from_width - 1) / from_width;
39 }
40
repackableSize(size_t src_size) const41 size_t Repacker::repackableSize(size_t src_size) const {
42 size_t bits = from_width * src_size;
43 assert(bits / from_width == src_size);
44 return bits / paddedWidth();
45 }
46
repack(const BinData & src,size_t start,size_t num_elements) const47 BinData Repacker::repack(const BinData& src, size_t start,
48 size_t num_elements) const {
49 unsigned repack_unit = repackUnit();
50 unsigned src_per_unit = repack_unit / from_width;
51 unsigned dst_per_unit = repack_unit / paddedWidth();
52 assert(src.width() == from_width);
53 BinData workspace(repack_unit, 1);
54 assert(start <= src.size());
55 num_elements = std::min(num_elements, repackableSize(src.size() - start));
56 BinData res(to_width, num_elements);
57 size_t src_end = start + repackSize(num_elements);
58 assert(src_end <= src.size());
59 for (size_t dst_pos = 0, src_pos = start; dst_pos < num_elements;) {
60 for (unsigned i = 0; i < src_per_unit && src_pos < src_end;
61 i++, src_pos++) {
62 unsigned work_pos;
63 switch (endian) {
64 case Endian::LITTLE:
65 work_pos = i * from_width;
66 break;
67 case Endian::BIG:
68 work_pos = (src_per_unit - i - 1) * from_width;
69 break;
70 default:
71 abort();
72 }
73 BinData::copyBits(workspace.rawData(), work_pos, src.rawData(src_pos), 0,
74 from_width);
75 }
76 for (unsigned i = 0; i < dst_per_unit && dst_pos < num_elements;
77 i++, dst_pos++) {
78 unsigned work_pos;
79 switch (endian) {
80 case Endian::LITTLE:
81 work_pos = i * paddedWidth() + low_pad;
82 break;
83 case Endian::BIG:
84 work_pos = (dst_per_unit - i - 1) * paddedWidth() + low_pad;
85 break;
86 default:
87 abort();
88 }
89 BinData::copyBits(res.rawData(dst_pos), 0, workspace.rawData(), work_pos,
90 to_width);
91 }
92 }
93 return res;
94 }
95
96 } // namespace data
97 } // namespace veles
98