Chris@69: /***********************************************************************
Chris@69: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
Chris@69: Redistribution and use in source and binary forms, with or without
Chris@69: modification, are permitted provided that the following conditions
Chris@69: are met:
Chris@69: - Redistributions of source code must retain the above copyright notice,
Chris@69: this list of conditions and the following disclaimer.
Chris@69: - Redistributions in binary form must reproduce the above copyright
Chris@69: notice, this list of conditions and the following disclaimer in the
Chris@69: documentation and/or other materials provided with the distribution.
Chris@69: - Neither the name of Internet Society, IETF or IETF Trust, nor the
Chris@69: names of specific contributors, may be used to endorse or promote
Chris@69: products derived from this software without specific prior written
Chris@69: permission.
Chris@69: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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Chris@69: POSSIBILITY OF SUCH DAMAGE.
Chris@69: ***********************************************************************/
Chris@69: 
Chris@69: #ifdef HAVE_CONFIG_H
Chris@69: #include "config.h"
Chris@69: #endif
Chris@69: 
Chris@69: #include "SigProc_FIX.h"
Chris@69: /* Approximation of 128 * log2() (very close inverse of silk_log2lin()) */
Chris@69: /* Convert input to a log scale    */
Chris@69: opus_int32 silk_lin2log(
Chris@69:     const opus_int32            inLin               /* I  input in linear scale                                         */
Chris@69: )
Chris@69: {
Chris@69:     opus_int32 lz, frac_Q7;
Chris@69: 
Chris@69:     silk_CLZ_FRAC( inLin, &lz, &frac_Q7 );
Chris@69: 
Chris@69:     /* Piece-wise parabolic approximation */
Chris@69:     return silk_ADD_LSHIFT32( silk_SMLAWB( frac_Q7, silk_MUL( frac_Q7, 128 - frac_Q7 ), 179 ), 31 - lz, 7 );
Chris@69: }
Chris@69: