Mercurial > hg > audiostuff

comparison spandsp-0.0.3/spandsp-0.0.3/src/bit_operations.c @ 5:f762bf195c4b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
import spandsp-0.0.3
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 16:00:21 +0200
parents
children
comparison
equal deleted inserted replaced
4:26cd8f1ef0b1 5:f762bf195c4b
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * bit_operations.c - Various bit level operations, such as bit reversal
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2006 Steve Underwood
9 *
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2, as
14 * published by the Free Software Foundation.
15 *
16 *
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 *
26 * $Id: bit_operations.c,v 1.5 2006/11/30 15:41:47 steveu Exp $
27 */
28
29 /*! \file */
30
31 #ifdef HAVE_CONFIG_H
32 #include "config.h"
33 #endif
34
35 #include <inttypes.h>
36 #include <stdlib.h>
37 #include <fcntl.h>
38 #include <string.h>
39 #include <assert.h>
40 #include <memory.h>
41
42 #include "spandsp/telephony.h"
43 #include "spandsp/bit_operations.h"
44
45 uint16_t bit_reverse16(uint16_t x)
46 {
47 x = (x >> 8) | (x << 8);
48 x = ((x & 0xF0F0) >> 4) | ((x & 0x0F0F) << 4);
49 x = ((x & 0xCCCC) >> 2) | ((x & 0x3333) << 2);
50 return ((x & 0xAAAA) >> 1) | ((x & 0x5555) << 1);
51 }
52 /*- End of function --------------------------------------------------------*/
53
54 uint32_t bit_reverse32(uint32_t x)
55 {
56 x = (x >> 16) | (x << 16);
57 x = ((x & 0xFF00FF00) >> 8) | ((x & 0x00FF00FF) << 8);
58 x = ((x & 0xF0F0F0F0) >> 4) | ((x & 0x0F0F0F0F) << 4);
59 x = ((x & 0xCCCCCCCC) >> 2) | ((x & 0x33333333) << 2);
60 return ((x & 0xAAAAAAAA) >> 1) | ((x & 0x55555555) << 1);
61 }
62 /*- End of function --------------------------------------------------------*/
63
64 uint32_t bit_reverse_4bytes(uint32_t x)
65 {
66 x = (x >> 4) | (x << 4);
67 x = ((x & 0xCCCCCCCC) >> 2) | ((x & 0x33333333) << 2);
68 return ((x & 0xAAAAAAAA) >> 1) | ((x & 0x55555555) << 1);
69 }
70 /*- End of function --------------------------------------------------------*/
71
72 int one_bits32(uint32_t x)
73 {
74 x = x - ((x >> 1) & 0x55555555);
75 /* We now have 16 2-bit counts */
76 x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
77 /* We now have 8 4-bit counts */
78 x = (x + (x >> 4)) & 0x0F0F0F0F;
79 /* We now have 4 8-bit counts */
80 #if defined(__i386__) || defined(__x86_64__)
81 /* If multiply is fast */
82 return (x*0x01010101) >> 24;
83 #else
84 /* If multiply is slow */
85 x += (x >> 8);
86 x += (x >> 16);
87 return (x & 0x0000003F);
88 #endif
89 }
90 /*- End of function --------------------------------------------------------*/
91
92 uint32_t make_mask32(uint32_t x)
93 {
94 x |= (x >> 1);
95 x |= (x >> 2);
96 x |= (x >> 4);
97 x |= (x >> 8);
98 x |= (x >> 16);
99 return x;
100 }
101 /*- End of function --------------------------------------------------------*/
102
103 uint16_t make_mask16(uint16_t x)
104 {
105 x |= (x >> 1);
106 x |= (x >> 2);
107 x |= (x >> 4);
108 x |= (x >> 8);
109 return x;
110 }
111 /*- End of function --------------------------------------------------------*/
112 /*- End of file ------------------------------------------------------------*/

Repositories maintained by Peter Meerwald, pmeerw@pmeerw.net.