188 lines
7.1 KiB
C
188 lines
7.1 KiB
C
/***********************************************************************
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Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of Internet Society, IETF or IETF Trust, nor the
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names of specific contributors, may be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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***********************************************************************/
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/*! \file silk_Inlines.h
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* \brief silk_Inlines.h defines OPUS_INLINE signal processing functions.
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*/
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#ifndef SILK_FIX_INLINES_H
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#define SILK_FIX_INLINES_H
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#ifdef __cplusplus
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extern "C"
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{
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#endif
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/* count leading zeros of opus_int64 */
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static OPUS_INLINE opus_int32 silk_CLZ64( opus_int64 in )
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{
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opus_int32 in_upper;
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in_upper = (opus_int32)silk_RSHIFT64(in, 32);
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if (in_upper == 0) {
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/* Search in the lower 32 bits */
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return 32 + silk_CLZ32( (opus_int32) in );
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} else {
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/* Search in the upper 32 bits */
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return silk_CLZ32( in_upper );
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}
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}
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/* get number of leading zeros and fractional part (the bits right after the leading one */
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static OPUS_INLINE void silk_CLZ_FRAC(
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opus_int32 in, /* I input */
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opus_int32 *lz, /* O number of leading zeros */
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opus_int32 *frac_Q7 /* O the 7 bits right after the leading one */
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)
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{
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opus_int32 lzeros = silk_CLZ32(in);
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* lz = lzeros;
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* frac_Q7 = silk_ROR32(in, 24 - lzeros) & 0x7f;
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}
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/* Approximation of square root */
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/* Accuracy: < +/- 10% for output values > 15 */
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/* < +/- 2.5% for output values > 120 */
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static OPUS_INLINE opus_int32 silk_SQRT_APPROX( opus_int32 x )
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{
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opus_int32 y, lz, frac_Q7;
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if( x <= 0 ) {
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return 0;
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}
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silk_CLZ_FRAC(x, &lz, &frac_Q7);
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if( lz & 1 ) {
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y = 32768;
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} else {
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y = 46214; /* 46214 = sqrt(2) * 32768 */
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}
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/* get scaling right */
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y >>= silk_RSHIFT(lz, 1);
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/* increment using fractional part of input */
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y = silk_SMLAWB(y, y, silk_SMULBB(213, frac_Q7));
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return y;
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}
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/* Divide two int32 values and return result as int32 in a given Q-domain */
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static OPUS_INLINE opus_int32 silk_DIV32_varQ( /* O returns a good approximation of "(a32 << Qres) / b32" */
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const opus_int32 a32, /* I numerator (Q0) */
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const opus_int32 b32, /* I denominator (Q0) */
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const opus_int Qres /* I Q-domain of result (>= 0) */
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)
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{
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opus_int a_headrm, b_headrm, lshift;
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opus_int32 b32_inv, a32_nrm, b32_nrm, result;
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silk_assert( b32 != 0 );
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silk_assert( Qres >= 0 );
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/* Compute number of bits head room and normalize inputs */
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a_headrm = silk_CLZ32( silk_abs(a32) ) - 1;
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a32_nrm = silk_LSHIFT(a32, a_headrm); /* Q: a_headrm */
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b_headrm = silk_CLZ32( silk_abs(b32) ) - 1;
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b32_nrm = silk_LSHIFT(b32, b_headrm); /* Q: b_headrm */
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/* Inverse of b32, with 14 bits of precision */
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b32_inv = silk_DIV32_16( silk_int32_MAX >> 2, silk_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
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/* First approximation */
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result = silk_SMULWB(a32_nrm, b32_inv); /* Q: 29 + a_headrm - b_headrm */
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/* Compute residual by subtracting product of denominator and first approximation */
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/* It's OK to overflow because the final value of a32_nrm should always be small */
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a32_nrm = silk_SUB32_ovflw(a32_nrm, silk_LSHIFT_ovflw( silk_SMMUL(b32_nrm, result), 3 )); /* Q: a_headrm */
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/* Refinement */
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result = silk_SMLAWB(result, a32_nrm, b32_inv); /* Q: 29 + a_headrm - b_headrm */
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/* Convert to Qres domain */
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lshift = 29 + a_headrm - b_headrm - Qres;
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if( lshift < 0 ) {
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return silk_LSHIFT_SAT32(result, -lshift);
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} else {
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if( lshift < 32){
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return silk_RSHIFT(result, lshift);
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} else {
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/* Avoid undefined result */
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return 0;
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}
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}
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}
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/* Invert int32 value and return result as int32 in a given Q-domain */
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static OPUS_INLINE opus_int32 silk_INVERSE32_varQ( /* O returns a good approximation of "(1 << Qres) / b32" */
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const opus_int32 b32, /* I denominator (Q0) */
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const opus_int Qres /* I Q-domain of result (> 0) */
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)
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{
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opus_int b_headrm, lshift;
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opus_int32 b32_inv, b32_nrm, err_Q32, result;
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silk_assert( b32 != 0 );
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silk_assert( Qres > 0 );
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/* Compute number of bits head room and normalize input */
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b_headrm = silk_CLZ32( silk_abs(b32) ) - 1;
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b32_nrm = silk_LSHIFT(b32, b_headrm); /* Q: b_headrm */
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/* Inverse of b32, with 14 bits of precision */
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b32_inv = silk_DIV32_16( silk_int32_MAX >> 2, silk_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
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/* First approximation */
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result = silk_LSHIFT(b32_inv, 16); /* Q: 61 - b_headrm */
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/* Compute residual by subtracting product of denominator and first approximation from one */
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err_Q32 = silk_LSHIFT( ((opus_int32)1<<29) - silk_SMULWB(b32_nrm, b32_inv), 3 ); /* Q32 */
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/* Refinement */
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result = silk_SMLAWW(result, err_Q32, b32_inv); /* Q: 61 - b_headrm */
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/* Convert to Qres domain */
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lshift = 61 - b_headrm - Qres;
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if( lshift <= 0 ) {
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return silk_LSHIFT_SAT32(result, -lshift);
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} else {
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if( lshift < 32){
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return silk_RSHIFT(result, lshift);
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}else{
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/* Avoid undefined result */
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return 0;
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}
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}
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* SILK_FIX_INLINES_H */
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