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27
28#ifdef HAVE_CONFIG_H
29#include "config.h"
30#endif
31
32#include "SigProc_FIX.h"
33/* Approximation of 128 * log2() (very close inverse of silk_log2lin()) */
34/* Convert input to a log scale    */
35opus_int32 silk_lin2log(
36    const opus_int32            inLin               /* I  input in linear scale                                         */
37)
38{
39    opus_int32 lz, frac_Q7;
40
41    silk_CLZ_FRAC( inLin, &lz, &frac_Q7 );
42
43    /* Piece-wise parabolic approximation */
44    return silk_LSHIFT( 31 - lz, 7 ) + silk_SMLAWB( frac_Q7, silk_MUL( frac_Q7, 128 - frac_Q7 ), 179 );
45}
46
47