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Staging: echo: remove bit_operations.h
This file is no longer needed, thanks to the work done by David. Cc: David Rowe <david@rowetel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Greg Kroah-Hartman
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/*
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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 General Public License version 2, as
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* 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 General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* 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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/*! \file */
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#if !defined(_BIT_OPERATIONS_H_)
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#define _BIT_OPERATIONS_H_
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#if defined(__i386__) || defined(__x86_64__)
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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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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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);
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return res;
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}
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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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__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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);
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return res;
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}
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#else
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static inline int top_bit(unsigned int bits)
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{
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int i;
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if (bits == 0)
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return -1;
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i = 0;
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if (bits & 0xFFFF0000) {
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bits &= 0xFFFF0000;
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i += 16;
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}
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if (bits & 0xFF00FF00) {
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bits &= 0xFF00FF00;
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i += 8;
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}
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if (bits & 0xF0F0F0F0) {
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bits &= 0xF0F0F0F0;
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i += 4;
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}
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if (bits & 0xCCCCCCCC) {
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bits &= 0xCCCCCCCC;
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i += 2;
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}
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if (bits & 0xAAAAAAAA) {
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bits &= 0xAAAAAAAA;
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i += 1;
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}
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return i;
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}
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static inline int bottom_bit(unsigned int bits)
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{
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int i;
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if (bits == 0)
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return -1;
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i = 32;
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if (bits & 0x0000FFFF) {
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bits &= 0x0000FFFF;
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i -= 16;
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}
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if (bits & 0x00FF00FF) {
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bits &= 0x00FF00FF;
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i -= 8;
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}
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if (bits & 0x0F0F0F0F) {
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bits &= 0x0F0F0F0F;
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i -= 4;
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}
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if (bits & 0x33333333) {
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bits &= 0x33333333;
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i -= 2;
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}
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if (bits & 0x55555555) {
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bits &= 0x55555555;
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i -= 1;
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}
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return i;
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}
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#endif
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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__)
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/* If multiply is fast */
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return ((x * 0x0802U & 0x22110U) | (x * 0x8020U & 0x88440U)) *
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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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/*! \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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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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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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uint32_t bit_reverse_4bytes(uint32_t data);
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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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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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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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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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/*! \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__)
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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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/*! \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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/*! \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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/*! \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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#endif
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/*- End of file ------------------------------------------------------------*/
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