315 lines
8.5 KiB
C
315 lines
8.5 KiB
C
/*
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* SpanDSP - a series of DSP components for telephony
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*
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* bit_operations.h - Various bit level operations, such as bit reversal
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2006 Steve Underwood
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 2.1,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id: bit_operations.h,v 1.27 2009/07/10 13:15:56 steveu Exp $
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*/
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/*! \file */
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#if !defined(_SPANDSP_BIT_OPERATIONS_H_)
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#define _SPANDSP_BIT_OPERATIONS_H_
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#if defined(__i386__) || defined(__x86_64__)
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#if !defined(__SUNPRO_C) || (__SUNPRO_C >= 0x0590)
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#define SPANDSP_USE_86_ASM
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#endif
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#endif
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#if defined(__cplusplus)
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extern "C"
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{
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#endif
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/*! \brief Find the bit position of the highest set bit in a word
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\param bits The word to be searched
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\return The bit number of the highest set bit, or -1 if the word is zero. */
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static __inline__ int top_bit(unsigned int bits)
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{
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#if defined(SPANDSP_USE_86_ASM)
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int res;
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__asm__ (" xorl %[res],%[res];\n"
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" decl %[res];\n"
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" bsrl %[bits],%[res]\n"
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: [res] "=&r" (res)
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: [bits] "rm" (bits));
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return res;
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#elif defined(__ppc__) || defined(__powerpc__)
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int res;
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__asm__ ("cntlzw %[res],%[bits];\n"
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: [res] "=&r" (res)
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: [bits] "r" (bits));
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return 31 - res;
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#elif defined(_M_IX86)
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/* Visual Studio i386 */
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__asm
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{
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xor eax, eax
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dec eax
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bsr eax, bits
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}
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#elif defined(_M_X64)
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/* Visual Studio x86_64 */
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/* TODO: Need the appropriate x86_64 code */
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int res;
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if (bits == 0)
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return -1;
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res = 0;
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if (bits & 0xFFFF0000)
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{
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bits &= 0xFFFF0000;
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res += 16;
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}
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if (bits & 0xFF00FF00)
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{
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bits &= 0xFF00FF00;
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res += 8;
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}
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if (bits & 0xF0F0F0F0)
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{
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bits &= 0xF0F0F0F0;
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res += 4;
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}
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if (bits & 0xCCCCCCCC)
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{
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bits &= 0xCCCCCCCC;
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res += 2;
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}
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if (bits & 0xAAAAAAAA)
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{
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bits &= 0xAAAAAAAA;
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res += 1;
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}
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return res;
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#else
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int res;
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if (bits == 0)
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return -1;
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res = 0;
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if (bits & 0xFFFF0000)
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{
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bits &= 0xFFFF0000;
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res += 16;
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}
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if (bits & 0xFF00FF00)
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{
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bits &= 0xFF00FF00;
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res += 8;
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}
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if (bits & 0xF0F0F0F0)
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{
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bits &= 0xF0F0F0F0;
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res += 4;
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}
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if (bits & 0xCCCCCCCC)
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{
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bits &= 0xCCCCCCCC;
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res += 2;
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}
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if (bits & 0xAAAAAAAA)
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{
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bits &= 0xAAAAAAAA;
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res += 1;
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}
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return res;
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#endif
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}
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/*- End of function --------------------------------------------------------*/
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/*! \brief Find the bit position of the lowest set bit in a word
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\param bits The word to be searched
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\return The bit number of the lowest set bit, or -1 if the word is zero. */
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static __inline__ int bottom_bit(unsigned int bits)
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{
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int res;
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#if defined(SPANDSP_USE_86_ASM)
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__asm__ (" xorl %[res],%[res];\n"
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" decl %[res];\n"
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" bsfl %[bits],%[res]\n"
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: [res] "=&r" (res)
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: [bits] "rm" (bits));
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return res;
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#else
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if (bits == 0)
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return -1;
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res = 31;
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if (bits & 0x0000FFFF)
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{
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bits &= 0x0000FFFF;
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res -= 16;
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}
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if (bits & 0x00FF00FF)
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{
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bits &= 0x00FF00FF;
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res -= 8;
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}
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if (bits & 0x0F0F0F0F)
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{
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bits &= 0x0F0F0F0F;
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res -= 4;
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}
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if (bits & 0x33333333)
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{
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bits &= 0x33333333;
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res -= 2;
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}
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if (bits & 0x55555555)
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{
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bits &= 0x55555555;
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res -= 1;
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}
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return res;
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#endif
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}
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/*- End of function --------------------------------------------------------*/
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/*! \brief Bit reverse a byte.
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\param data The byte to be reversed.
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\return The bit reversed version of data. */
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static __inline__ uint8_t bit_reverse8(uint8_t x)
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{
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#if defined(__i386__) || defined(__x86_64__) || defined(__ppc__) || defined(__powerpc__)
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/* If multiply is fast */
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return ((x*0x0802U & 0x22110U) | (x*0x8020U & 0x88440U))*0x10101U >> 16;
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#else
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/* If multiply is slow, but we have a barrel shifter */
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x = (x >> 4) | (x << 4);
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x = ((x & 0xCC) >> 2) | ((x & 0x33) << 2);
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return ((x & 0xAA) >> 1) | ((x & 0x55) << 1);
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#endif
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}
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/*- End of function --------------------------------------------------------*/
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/*! \brief Bit reverse a 16 bit word.
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\param data The word to be reversed.
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\return The bit reversed version of data. */
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SPAN_DECLARE(uint16_t) bit_reverse16(uint16_t data);
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/*! \brief Bit reverse a 32 bit word.
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\param data The word to be reversed.
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\return The bit reversed version of data. */
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SPAN_DECLARE(uint32_t) bit_reverse32(uint32_t data);
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/*! \brief Bit reverse each of the four bytes in a 32 bit word.
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\param data The word to be reversed.
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\return The bit reversed version of data. */
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SPAN_DECLARE(uint32_t) bit_reverse_4bytes(uint32_t data);
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#if defined(__x86_64__)
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/*! \brief Bit reverse each of the eight bytes in a 64 bit word.
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\param data The word to be reversed.
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\return The bit reversed version of data. */
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SPAN_DECLARE(uint64_t) bit_reverse_8bytes(uint64_t data);
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#endif
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/*! \brief Bit reverse each bytes in a buffer.
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\param to The buffer to place the reversed data in.
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\param from The buffer containing the data to be reversed.
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\param len The length of the data in the buffer. */
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SPAN_DECLARE(void) bit_reverse(uint8_t to[], const uint8_t from[], int len);
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/*! \brief Find the number of set bits in a 32 bit word.
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\param x The word to be searched.
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\return The number of set bits. */
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SPAN_DECLARE(int) one_bits32(uint32_t x);
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/*! \brief Create a mask as wide as the number in a 32 bit word.
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\param x The word to be searched.
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\return The mask. */
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SPAN_DECLARE(uint32_t) make_mask32(uint32_t x);
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/*! \brief Create a mask as wide as the number in a 16 bit word.
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\param x The word to be searched.
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\return The mask. */
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SPAN_DECLARE(uint16_t) make_mask16(uint16_t x);
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/*! \brief Find the least significant one in a word, and return a word
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with just that bit set.
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\param x The word to be searched.
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\return The word with the single set bit. */
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static __inline__ uint32_t least_significant_one32(uint32_t x)
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{
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return (x & (-(int32_t) x));
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}
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/*- End of function --------------------------------------------------------*/
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/*! \brief Find the most significant one in a word, and return a word
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with just that bit set.
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\param x The word to be searched.
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\return The word with the single set bit. */
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static __inline__ uint32_t most_significant_one32(uint32_t x)
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{
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#if defined(__i386__) || defined(__x86_64__) || defined(__ppc__) || defined(__powerpc__)
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return 1 << top_bit(x);
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#else
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x = make_mask32(x);
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return (x ^ (x >> 1));
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#endif
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}
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/*- End of function --------------------------------------------------------*/
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/*! \brief Find the parity of a byte.
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\param x The byte to be checked.
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\return 1 for odd, or 0 for even. */
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static __inline__ int parity8(uint8_t x)
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{
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x = (x ^ (x >> 4)) & 0x0F;
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return (0x6996 >> x) & 1;
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}
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/*- End of function --------------------------------------------------------*/
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/*! \brief Find the parity of a 16 bit word.
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\param x The word to be checked.
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\return 1 for odd, or 0 for even. */
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static __inline__ int parity16(uint16_t x)
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{
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x ^= (x >> 8);
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x = (x ^ (x >> 4)) & 0x0F;
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return (0x6996 >> x) & 1;
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}
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/*- End of function --------------------------------------------------------*/
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/*! \brief Find the parity of a 32 bit word.
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\param x The word to be checked.
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\return 1 for odd, or 0 for even. */
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static __inline__ int parity32(uint32_t x)
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{
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x ^= (x >> 16);
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x ^= (x >> 8);
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x = (x ^ (x >> 4)) & 0x0F;
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return (0x6996 >> x) & 1;
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}
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/*- End of function --------------------------------------------------------*/
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#if defined(__cplusplus)
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}
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#endif
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#endif
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/*- End of file ------------------------------------------------------------*/
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