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27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 /* Insertion sort (fast for already almost sorted arrays): */
33 /* Best case: O(n) for an already sorted array */
34 /* Worst case: O(n^2) for an inversely sorted array */
35
36 #include "typedef.h"
37 #include "SigProc_FLP.h"
38
silk_insertion_sort_decreasing_FLP(silk_float * a,opus_int * idx,const opus_int L,const opus_int K)39 void silk_insertion_sort_decreasing_FLP(
40 silk_float *a, /* I/O Unsorted / Sorted vector */
41 opus_int *idx, /* O Index vector for the sorted elements */
42 const opus_int L, /* I Vector length */
43 const opus_int K /* I Number of correctly sorted positions */
44 )
45 {
46 silk_float value;
47 opus_int i, j;
48
49 /* Safety checks */
50 silk_assert( K > 0 );
51 silk_assert( L > 0 );
52 silk_assert( L >= K );
53
54 /* Write start indices in index vector */
55 for( i = 0; i < K; i++ ) {
56 idx[ i ] = i;
57 }
58
59 /* Sort vector elements by value, decreasing order */
60 for( i = 1; i < K; i++ ) {
61 value = a[ i ];
62 for( j = i - 1; ( j >= 0 ) && ( value > a[ j ] ); j-- ) {
63 a[ j + 1 ] = a[ j ]; /* Shift value */
64 idx[ j + 1 ] = idx[ j ]; /* Shift index */
65 }
66 a[ j + 1 ] = value; /* Write value */
67 idx[ j + 1 ] = i; /* Write index */
68 }
69
70 /* If less than L values are asked check the remaining values, */
71 /* but only spend CPU to ensure that the K first values are correct */
72 for( i = K; i < L; i++ ) {
73 value = a[ i ];
74 if( value > a[ K - 1 ] ) {
75 for( j = K - 2; ( j >= 0 ) && ( value > a[ j ] ); j-- ) {
76 a[ j + 1 ] = a[ j ]; /* Shift value */
77 idx[ j + 1 ] = idx[ j ]; /* Shift index */
78 }
79 a[ j + 1 ] = value; /* Write value */
80 idx[ j + 1 ] = i; /* Write index */
81 }
82 }
83 }
84