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116 lines
3.7 KiB
C
116 lines
3.7 KiB
C
/* libFLAC - Free Lossless Audio Codec library
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* Copyright (C) 2001-2009 Josh Coalson
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* Copyright (C) 2011-2024 Xiph.Org Foundation
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*
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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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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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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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*
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* - Neither the name of the Xiph.org Foundation nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "private/bitmath.h"
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/* An example of what FLAC__bitmath_silog2() computes:
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*
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* silog2(-10) = 5
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* silog2(- 9) = 5
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* silog2(- 8) = 4
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* silog2(- 7) = 4
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* silog2(- 6) = 4
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* silog2(- 5) = 4
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* silog2(- 4) = 3
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* silog2(- 3) = 3
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* silog2(- 2) = 2
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* silog2(- 1) = 2
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* silog2( 0) = 0
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* silog2( 1) = 2
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* silog2( 2) = 3
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* silog2( 3) = 3
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* silog2( 4) = 4
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* silog2( 5) = 4
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* silog2( 6) = 4
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* silog2( 7) = 4
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* silog2( 8) = 5
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* silog2( 9) = 5
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* silog2( 10) = 5
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*/
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uint32_t FLAC__bitmath_silog2(FLAC__int64 v)
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{
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if(v == 0)
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return 0;
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if(v == -1)
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return 2;
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v = (v < 0) ? (-(v+1)) : v;
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return FLAC__bitmath_ilog2_wide(v)+2;
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}
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/* An example of what FLAC__bitmath_extra_mulbits_unsigned() computes:
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*
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* extra_mulbits_unsigned( 0) = 0
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* extra_mulbits_unsigned( 1) = 0
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* extra_mulbits_unsigned( 2) = 1
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* extra_mulbits_unsigned( 3) = 2
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* extra_mulbits_unsigned( 4) = 2
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* extra_mulbits_unsigned( 5) = 3
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* extra_mulbits_unsigned( 6) = 3
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* extra_mulbits_unsigned( 7) = 3
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* extra_mulbits_unsigned( 8) = 3
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* extra_mulbits_unsigned( 9) = 4
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* extra_mulbits_unsigned(10) = 4
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* extra_mulbits_unsigned(11) = 4
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* extra_mulbits_unsigned(12) = 4
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* extra_mulbits_unsigned(13) = 4
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* extra_mulbits_unsigned(14) = 4
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* extra_mulbits_unsigned(15) = 4
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* extra_mulbits_unsigned(16) = 4
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* extra_mulbits_unsigned(17) = 5
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* extra_mulbits_unsigned(18) = 5
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*
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* The intent of this is to calculate how many extra bits multiplication
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* by a certain number requires. So, if a signal fits in a certain number
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* of bits (for example 16) than multiplying by a number (for example 1024)
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* grows that storage requirement (to 26 in this example). In effect this is
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* is the log2 rounded up.
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*/
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uint32_t FLAC__bitmath_extra_mulbits_unsigned(FLAC__uint32 v)
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{
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uint32_t ilog2;
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if(v == 0)
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return 0;
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ilog2 = FLAC__bitmath_ilog2(v);
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if(((v >> ilog2) << ilog2) == v)
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/* v is power of 2 */
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return ilog2;
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else
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/* v is not a power of 2, return one higher */
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return ilog2 + 1;
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}
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