vx32

Local 9vx git repository for patches.
git clone git://r-36.net/vx32
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bitmath.c (3303B)


      1 /* libFLAC - Free Lossless Audio Codec library
      2  * Copyright (C) 2001,2002,2003,2004,2005  Josh Coalson
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  *
      8  * - Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *
     11  * - Redistributions in binary form must reproduce the above copyright
     12  * notice, this list of conditions and the following disclaimer in the
     13  * documentation and/or other materials provided with the distribution.
     14  *
     15  * - Neither the name of the Xiph.org Foundation nor the names of its
     16  * contributors may be used to endorse or promote products derived from
     17  * this software without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     22  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
     23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     24  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     25  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     26  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     27  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     28  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     29  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include "private/bitmath.h"
     33 #include "FLAC/assert.h"
     34 
     35 /* An example of what FLAC__bitmath_ilog2() computes:
     36  *
     37  * ilog2( 0) = assertion failure
     38  * ilog2( 1) = 0
     39  * ilog2( 2) = 1
     40  * ilog2( 3) = 1
     41  * ilog2( 4) = 2
     42  * ilog2( 5) = 2
     43  * ilog2( 6) = 2
     44  * ilog2( 7) = 2
     45  * ilog2( 8) = 3
     46  * ilog2( 9) = 3
     47  * ilog2(10) = 3
     48  * ilog2(11) = 3
     49  * ilog2(12) = 3
     50  * ilog2(13) = 3
     51  * ilog2(14) = 3
     52  * ilog2(15) = 3
     53  * ilog2(16) = 4
     54  * ilog2(17) = 4
     55  * ilog2(18) = 4
     56  */
     57 unsigned FLAC__bitmath_ilog2(FLAC__uint32 v)
     58 {
     59 	unsigned l = 0;
     60 	FLAC__ASSERT(v > 0);
     61 	while(v >>= 1)
     62 		l++;
     63 	return l;
     64 }
     65 
     66 unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v)
     67 {
     68 	unsigned l = 0;
     69 	FLAC__ASSERT(v > 0);
     70 	while(v >>= 1)
     71 		l++;
     72 	return l;
     73 }
     74 
     75 /* An example of what FLAC__bitmath_silog2() computes:
     76  *
     77  * silog2(-10) = 5
     78  * silog2(- 9) = 5
     79  * silog2(- 8) = 4
     80  * silog2(- 7) = 4
     81  * silog2(- 6) = 4
     82  * silog2(- 5) = 4
     83  * silog2(- 4) = 3
     84  * silog2(- 3) = 3
     85  * silog2(- 2) = 2
     86  * silog2(- 1) = 2
     87  * silog2(  0) = 0
     88  * silog2(  1) = 2
     89  * silog2(  2) = 3
     90  * silog2(  3) = 3
     91  * silog2(  4) = 4
     92  * silog2(  5) = 4
     93  * silog2(  6) = 4
     94  * silog2(  7) = 4
     95  * silog2(  8) = 5
     96  * silog2(  9) = 5
     97  * silog2( 10) = 5
     98  */
     99 unsigned FLAC__bitmath_silog2(int v)
    100 {
    101 	while(1) {
    102 		if(v == 0) {
    103 			return 0;
    104 		}
    105 		else if(v > 0) {
    106 			unsigned l = 0;
    107 			while(v) {
    108 				l++;
    109 				v >>= 1;
    110 			}
    111 			return l+1;
    112 		}
    113 		else if(v == -1) {
    114 			return 2;
    115 		}
    116 		else {
    117 			v++;
    118 			v = -v;
    119 		}
    120 	}
    121 }
    122 
    123 unsigned FLAC__bitmath_silog2_wide(FLAC__int64 v)
    124 {
    125 	while(1) {
    126 		if(v == 0) {
    127 			return 0;
    128 		}
    129 		else if(v > 0) {
    130 			unsigned l = 0;
    131 			while(v) {
    132 				l++;
    133 				v >>= 1;
    134 			}
    135 			return l+1;
    136 		}
    137 		else if(v == -1) {
    138 			return 2;
    139 		}
    140 		else {
    141 			v++;
    142 			v = -v;
    143 		}
    144 	}
    145 }