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media/libopus/silk/Inlines.h@b8a032363ba2 (annotated)

media/libopus/silk/Inlines.h

Thu, 22 Jan 2015 13:21:57 +0100

author
Michael Schloh von Bennewitz <michael@schloh.com>
date
Thu, 22 Jan 2015 13:21:57 +0100
branch
TOR_BUG_9701
changeset 15
b8a032363ba2
permissions
-rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

michael@0 1 /***********************************************************************
michael@0 2 Copyright (c) 2006-2011, Skype Limited. All rights reserved.
michael@0 3 Redistribution and use in source and binary forms, with or without
michael@0 4 modification, are permitted provided that the following conditions
michael@0 5 are met:
michael@0 6 - Redistributions of source code must retain the above copyright notice,
michael@0 7 this list of conditions and the following disclaimer.
michael@0 8 - Redistributions in binary form must reproduce the above copyright
michael@0 9 notice, this list of conditions and the following disclaimer in the
michael@0 10 documentation and/or other materials provided with the distribution.
michael@0 11 - Neither the name of Internet Society, IETF or IETF Trust, nor the
michael@0 12 names of specific contributors, may be used to endorse or promote
michael@0 13 products derived from this software without specific prior written
michael@0 14 permission.
michael@0 15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
michael@0 16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
michael@0 17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
michael@0 18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
michael@0 19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
michael@0 20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
michael@0 21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
michael@0 22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
michael@0 23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
michael@0 24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
michael@0 25 POSSIBILITY OF SUCH DAMAGE.
michael@0 26 ***********************************************************************/
michael@0 27
michael@0 28 /*! \file silk_Inlines.h
michael@0 29 * \brief silk_Inlines.h defines OPUS_INLINE signal processing functions.
michael@0 30 */
michael@0 31
michael@0 32 #ifndef SILK_FIX_INLINES_H
michael@0 33 #define SILK_FIX_INLINES_H
michael@0 34
michael@0 35 #ifdef __cplusplus
michael@0 36 extern "C"
michael@0 37 {
michael@0 38 #endif
michael@0 39
michael@0 40 /* count leading zeros of opus_int64 */
michael@0 41 static OPUS_INLINE opus_int32 silk_CLZ64( opus_int64 in )
michael@0 42 {
michael@0 43 opus_int32 in_upper;
michael@0 44
michael@0 45 in_upper = (opus_int32)silk_RSHIFT64(in, 32);
michael@0 46 if (in_upper == 0) {
michael@0 47 /* Search in the lower 32 bits */
michael@0 48 return 32 + silk_CLZ32( (opus_int32) in );
michael@0 49 } else {
michael@0 50 /* Search in the upper 32 bits */
michael@0 51 return silk_CLZ32( in_upper );
michael@0 52 }
michael@0 53 }
michael@0 54
michael@0 55 /* get number of leading zeros and fractional part (the bits right after the leading one */
michael@0 56 static OPUS_INLINE void silk_CLZ_FRAC(
michael@0 57 opus_int32 in, /* I input */
michael@0 58 opus_int32 *lz, /* O number of leading zeros */
michael@0 59 opus_int32 *frac_Q7 /* O the 7 bits right after the leading one */
michael@0 60 )
michael@0 61 {
michael@0 62 opus_int32 lzeros = silk_CLZ32(in);
michael@0 63
michael@0 64 * lz = lzeros;
michael@0 65 * frac_Q7 = silk_ROR32(in, 24 - lzeros) & 0x7f;
michael@0 66 }
michael@0 67
michael@0 68 /* Approximation of square root */
michael@0 69 /* Accuracy: < +/- 10% for output values > 15 */
michael@0 70 /* < +/- 2.5% for output values > 120 */
michael@0 71 static OPUS_INLINE opus_int32 silk_SQRT_APPROX( opus_int32 x )
michael@0 72 {
michael@0 73 opus_int32 y, lz, frac_Q7;
michael@0 74
michael@0 75 if( x <= 0 ) {
michael@0 76 return 0;
michael@0 77 }
michael@0 78
michael@0 79 silk_CLZ_FRAC(x, &lz, &frac_Q7);
michael@0 80
michael@0 81 if( lz & 1 ) {
michael@0 82 y = 32768;
michael@0 83 } else {
michael@0 84 y = 46214; /* 46214 = sqrt(2) * 32768 */
michael@0 85 }
michael@0 86
michael@0 87 /* get scaling right */
michael@0 88 y >>= silk_RSHIFT(lz, 1);
michael@0 89
michael@0 90 /* increment using fractional part of input */
michael@0 91 y = silk_SMLAWB(y, y, silk_SMULBB(213, frac_Q7));
michael@0 92
michael@0 93 return y;
michael@0 94 }
michael@0 95
michael@0 96 /* Divide two int32 values and return result as int32 in a given Q-domain */
michael@0 97 static OPUS_INLINE opus_int32 silk_DIV32_varQ( /* O returns a good approximation of "(a32 << Qres) / b32" */
michael@0 98 const opus_int32 a32, /* I numerator (Q0) */
michael@0 99 const opus_int32 b32, /* I denominator (Q0) */
michael@0 100 const opus_int Qres /* I Q-domain of result (>= 0) */
michael@0 101 )
michael@0 102 {
michael@0 103 opus_int a_headrm, b_headrm, lshift;
michael@0 104 opus_int32 b32_inv, a32_nrm, b32_nrm, result;
michael@0 105
michael@0 106 silk_assert( b32 != 0 );
michael@0 107 silk_assert( Qres >= 0 );
michael@0 108
michael@0 109 /* Compute number of bits head room and normalize inputs */
michael@0 110 a_headrm = silk_CLZ32( silk_abs(a32) ) - 1;
michael@0 111 a32_nrm = silk_LSHIFT(a32, a_headrm); /* Q: a_headrm */
michael@0 112 b_headrm = silk_CLZ32( silk_abs(b32) ) - 1;
michael@0 113 b32_nrm = silk_LSHIFT(b32, b_headrm); /* Q: b_headrm */
michael@0 114
michael@0 115 /* Inverse of b32, with 14 bits of precision */
michael@0 116 b32_inv = silk_DIV32_16( silk_int32_MAX >> 2, silk_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
michael@0 117
michael@0 118 /* First approximation */
michael@0 119 result = silk_SMULWB(a32_nrm, b32_inv); /* Q: 29 + a_headrm - b_headrm */
michael@0 120
michael@0 121 /* Compute residual by subtracting product of denominator and first approximation */
michael@0 122 /* It's OK to overflow because the final value of a32_nrm should always be small */
michael@0 123 a32_nrm = silk_SUB32_ovflw(a32_nrm, silk_LSHIFT_ovflw( silk_SMMUL(b32_nrm, result), 3 )); /* Q: a_headrm */
michael@0 124
michael@0 125 /* Refinement */
michael@0 126 result = silk_SMLAWB(result, a32_nrm, b32_inv); /* Q: 29 + a_headrm - b_headrm */
michael@0 127
michael@0 128 /* Convert to Qres domain */
michael@0 129 lshift = 29 + a_headrm - b_headrm - Qres;
michael@0 130 if( lshift < 0 ) {
michael@0 131 return silk_LSHIFT_SAT32(result, -lshift);
michael@0 132 } else {
michael@0 133 if( lshift < 32){
michael@0 134 return silk_RSHIFT(result, lshift);
michael@0 135 } else {
michael@0 136 /* Avoid undefined result */
michael@0 137 return 0;
michael@0 138 }
michael@0 139 }
michael@0 140 }
michael@0 141
michael@0 142 /* Invert int32 value and return result as int32 in a given Q-domain */
michael@0 143 static OPUS_INLINE opus_int32 silk_INVERSE32_varQ( /* O returns a good approximation of "(1 << Qres) / b32" */
michael@0 144 const opus_int32 b32, /* I denominator (Q0) */
michael@0 145 const opus_int Qres /* I Q-domain of result (> 0) */
michael@0 146 )
michael@0 147 {
michael@0 148 opus_int b_headrm, lshift;
michael@0 149 opus_int32 b32_inv, b32_nrm, err_Q32, result;
michael@0 150
michael@0 151 silk_assert( b32 != 0 );
michael@0 152 silk_assert( Qres > 0 );
michael@0 153
michael@0 154 /* Compute number of bits head room and normalize input */
michael@0 155 b_headrm = silk_CLZ32( silk_abs(b32) ) - 1;
michael@0 156 b32_nrm = silk_LSHIFT(b32, b_headrm); /* Q: b_headrm */
michael@0 157
michael@0 158 /* Inverse of b32, with 14 bits of precision */
michael@0 159 b32_inv = silk_DIV32_16( silk_int32_MAX >> 2, silk_RSHIFT(b32_nrm, 16) ); /* Q: 29 + 16 - b_headrm */
michael@0 160
michael@0 161 /* First approximation */
michael@0 162 result = silk_LSHIFT(b32_inv, 16); /* Q: 61 - b_headrm */
michael@0 163
michael@0 164 /* Compute residual by subtracting product of denominator and first approximation from one */
michael@0 165 err_Q32 = silk_LSHIFT( ((opus_int32)1<<29) - silk_SMULWB(b32_nrm, b32_inv), 3 ); /* Q32 */
michael@0 166
michael@0 167 /* Refinement */
michael@0 168 result = silk_SMLAWW(result, err_Q32, b32_inv); /* Q: 61 - b_headrm */
michael@0 169
michael@0 170 /* Convert to Qres domain */
michael@0 171 lshift = 61 - b_headrm - Qres;
michael@0 172 if( lshift <= 0 ) {
michael@0 173 return silk_LSHIFT_SAT32(result, -lshift);
michael@0 174 } else {
michael@0 175 if( lshift < 32){
michael@0 176 return silk_RSHIFT(result, lshift);
michael@0 177 }else{
michael@0 178 /* Avoid undefined result */
michael@0 179 return 0;
michael@0 180 }
michael@0 181 }
michael@0 182 }
michael@0 183
michael@0 184 #ifdef __cplusplus
michael@0 185 }
michael@0 186 #endif
michael@0 187
michael@0 188 #endif /* SILK_FIX_INLINES_H */

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