xref: /aosp_15_r20/external/brotli/c/enc/cluster.c (revision f4ee7fba7774faf2a30f13154332c0a06550dbc4)
1*f4ee7fbaSAndroid Build Coastguard Worker /* Copyright 2013 Google Inc. All Rights Reserved.
2*f4ee7fbaSAndroid Build Coastguard Worker 
3*f4ee7fbaSAndroid Build Coastguard Worker    Distributed under MIT license.
4*f4ee7fbaSAndroid Build Coastguard Worker    See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
5*f4ee7fbaSAndroid Build Coastguard Worker */
6*f4ee7fbaSAndroid Build Coastguard Worker 
7*f4ee7fbaSAndroid Build Coastguard Worker /* Functions for clustering similar histograms together. */
8*f4ee7fbaSAndroid Build Coastguard Worker 
9*f4ee7fbaSAndroid Build Coastguard Worker #include "./cluster.h"
10*f4ee7fbaSAndroid Build Coastguard Worker 
11*f4ee7fbaSAndroid Build Coastguard Worker #include "../common/platform.h"
12*f4ee7fbaSAndroid Build Coastguard Worker #include <brotli/types.h>
13*f4ee7fbaSAndroid Build Coastguard Worker #include "./bit_cost.h"  /* BrotliPopulationCost */
14*f4ee7fbaSAndroid Build Coastguard Worker #include "./fast_log.h"
15*f4ee7fbaSAndroid Build Coastguard Worker #include "./histogram.h"
16*f4ee7fbaSAndroid Build Coastguard Worker #include "./memory.h"
17*f4ee7fbaSAndroid Build Coastguard Worker 
18*f4ee7fbaSAndroid Build Coastguard Worker #if defined(__cplusplus) || defined(c_plusplus)
19*f4ee7fbaSAndroid Build Coastguard Worker extern "C" {
20*f4ee7fbaSAndroid Build Coastguard Worker #endif
21*f4ee7fbaSAndroid Build Coastguard Worker 
HistogramPairIsLess(const HistogramPair * p1,const HistogramPair * p2)22*f4ee7fbaSAndroid Build Coastguard Worker static BROTLI_INLINE BROTLI_BOOL HistogramPairIsLess(
23*f4ee7fbaSAndroid Build Coastguard Worker     const HistogramPair* p1, const HistogramPair* p2) {
24*f4ee7fbaSAndroid Build Coastguard Worker   if (p1->cost_diff != p2->cost_diff) {
25*f4ee7fbaSAndroid Build Coastguard Worker     return TO_BROTLI_BOOL(p1->cost_diff > p2->cost_diff);
26*f4ee7fbaSAndroid Build Coastguard Worker   }
27*f4ee7fbaSAndroid Build Coastguard Worker   return TO_BROTLI_BOOL((p1->idx2 - p1->idx1) > (p2->idx2 - p2->idx1));
28*f4ee7fbaSAndroid Build Coastguard Worker }
29*f4ee7fbaSAndroid Build Coastguard Worker 
30*f4ee7fbaSAndroid Build Coastguard Worker /* Returns entropy reduction of the context map when we combine two clusters. */
ClusterCostDiff(size_t size_a,size_t size_b)31*f4ee7fbaSAndroid Build Coastguard Worker static BROTLI_INLINE double ClusterCostDiff(size_t size_a, size_t size_b) {
32*f4ee7fbaSAndroid Build Coastguard Worker   size_t size_c = size_a + size_b;
33*f4ee7fbaSAndroid Build Coastguard Worker   return (double)size_a * FastLog2(size_a) +
34*f4ee7fbaSAndroid Build Coastguard Worker     (double)size_b * FastLog2(size_b) -
35*f4ee7fbaSAndroid Build Coastguard Worker     (double)size_c * FastLog2(size_c);
36*f4ee7fbaSAndroid Build Coastguard Worker }
37*f4ee7fbaSAndroid Build Coastguard Worker 
38*f4ee7fbaSAndroid Build Coastguard Worker #define CODE(X) X
39*f4ee7fbaSAndroid Build Coastguard Worker 
40*f4ee7fbaSAndroid Build Coastguard Worker #define FN(X) X ## Literal
41*f4ee7fbaSAndroid Build Coastguard Worker #include "./cluster_inc.h"  /* NOLINT(build/include) */
42*f4ee7fbaSAndroid Build Coastguard Worker #undef FN
43*f4ee7fbaSAndroid Build Coastguard Worker 
44*f4ee7fbaSAndroid Build Coastguard Worker #define FN(X) X ## Command
45*f4ee7fbaSAndroid Build Coastguard Worker #include "./cluster_inc.h"  /* NOLINT(build/include) */
46*f4ee7fbaSAndroid Build Coastguard Worker #undef FN
47*f4ee7fbaSAndroid Build Coastguard Worker 
48*f4ee7fbaSAndroid Build Coastguard Worker #define FN(X) X ## Distance
49*f4ee7fbaSAndroid Build Coastguard Worker #include "./cluster_inc.h"  /* NOLINT(build/include) */
50*f4ee7fbaSAndroid Build Coastguard Worker #undef FN
51*f4ee7fbaSAndroid Build Coastguard Worker 
52*f4ee7fbaSAndroid Build Coastguard Worker #undef CODE
53*f4ee7fbaSAndroid Build Coastguard Worker 
54*f4ee7fbaSAndroid Build Coastguard Worker #if defined(__cplusplus) || defined(c_plusplus)
55*f4ee7fbaSAndroid Build Coastguard Worker }  /* extern "C" */
56*f4ee7fbaSAndroid Build Coastguard Worker #endif
57