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comparison mupdf-source/thirdparty/brotli/c/enc/bit_cost.h @ 2:b50eed0cc0ef upstream

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ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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1:1d09e1dec1d9 2:b50eed0cc0ef
1 /* Copyright 2013 Google Inc. All Rights Reserved.
2
3 Distributed under MIT license.
4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
5 */
6
7 /* Functions to estimate the bit cost of Huffman trees. */
8
9 #ifndef BROTLI_ENC_BIT_COST_H_
10 #define BROTLI_ENC_BIT_COST_H_
11
12 #include <brotli/types.h>
13
14 #include "../common/platform.h"
15 #include "fast_log.h"
16 #include "histogram.h"
17
18 #if defined(__cplusplus) || defined(c_plusplus)
19 extern "C" {
20 #endif
21
22 static BROTLI_INLINE double ShannonEntropy(
23 const uint32_t* population, size_t size, size_t* total) {
24 size_t sum = 0;
25 double retval = 0;
26 const uint32_t* population_end = population + size;
27 size_t p;
28 if (size & 1) {
29 goto odd_number_of_elements_left;
30 }
31 while (population < population_end) {
32 p = *population++;
33 sum += p;
34 retval -= (double)p * FastLog2(p);
35 odd_number_of_elements_left:
36 p = *population++;
37 sum += p;
38 retval -= (double)p * FastLog2(p);
39 }
40 if (sum) retval += (double)sum * FastLog2(sum);
41 *total = sum;
42 return retval;
43 }
44
45 static BROTLI_INLINE double BitsEntropy(
46 const uint32_t* population, size_t size) {
47 size_t sum;
48 double retval = ShannonEntropy(population, size, &sum);
49 if (retval < (double)sum) {
50 /* At least one bit per literal is needed. */
51 retval = (double)sum;
52 }
53 return retval;
54 }
55
56 BROTLI_INTERNAL double BrotliPopulationCostLiteral(const HistogramLiteral*);
57 BROTLI_INTERNAL double BrotliPopulationCostCommand(const HistogramCommand*);
58 BROTLI_INTERNAL double BrotliPopulationCostDistance(const HistogramDistance*);
59
60 #if defined(__cplusplus) || defined(c_plusplus)
61 } /* extern "C" */
62 #endif
63
64 #endif /* BROTLI_ENC_BIT_COST_H_ */