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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
39void 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