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Diffstat (limited to 'drivers/staging/echo/bit_operations.h')
-rw-r--r-- | drivers/staging/echo/bit_operations.h | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/drivers/staging/echo/bit_operations.h b/drivers/staging/echo/bit_operations.h new file mode 100644 index 00000000000..b32f4bf9939 --- /dev/null +++ b/drivers/staging/echo/bit_operations.h @@ -0,0 +1,253 @@ +/* + * SpanDSP - a series of DSP components for telephony + * + * bit_operations.h - Various bit level operations, such as bit reversal + * + * Written by Steve Underwood <steveu@coppice.org> + * + * Copyright (C) 2006 Steve Underwood + * + * All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2, as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * + * $Id: bit_operations.h,v 1.11 2006/11/28 15:37:03 steveu Exp $ + */ + +/*! \file */ + +#if !defined(_BIT_OPERATIONS_H_) +#define _BIT_OPERATIONS_H_ + +#ifdef __cplusplus +extern "C" { +#endif + +#if defined(__i386__) || defined(__x86_64__) +/*! \brief Find the bit position of the highest set bit in a word + \param bits The word to be searched + \return The bit number of the highest set bit, or -1 if the word is zero. */ +static __inline__ int top_bit(unsigned int bits) +{ + int res; + + __asm__ (" xorl %[res],%[res];\n" + " decl %[res];\n" + " bsrl %[bits],%[res]\n" + : [res] "=&r" (res) + : [bits] "rm" (bits)); + return res; +} +/*- End of function --------------------------------------------------------*/ + +/*! \brief Find the bit position of the lowest set bit in a word + \param bits The word to be searched + \return The bit number of the lowest set bit, or -1 if the word is zero. */ +static __inline__ int bottom_bit(unsigned int bits) +{ + int res; + + __asm__ (" xorl %[res],%[res];\n" + " decl %[res];\n" + " bsfl %[bits],%[res]\n" + : [res] "=&r" (res) + : [bits] "rm" (bits)); + return res; +} +/*- End of function --------------------------------------------------------*/ +#else +static __inline__ int top_bit(unsigned int bits) +{ + int i; + + if (bits == 0) + return -1; + i = 0; + if (bits & 0xFFFF0000) + { + bits &= 0xFFFF0000; + i += 16; + } + if (bits & 0xFF00FF00) + { + bits &= 0xFF00FF00; + i += 8; + } + if (bits & 0xF0F0F0F0) + { + bits &= 0xF0F0F0F0; + i += 4; + } + if (bits & 0xCCCCCCCC) + { + bits &= 0xCCCCCCCC; + i += 2; + } + if (bits & 0xAAAAAAAA) + { + bits &= 0xAAAAAAAA; + i += 1; + } + return i; +} +/*- End of function --------------------------------------------------------*/ + +static __inline__ int bottom_bit(unsigned int bits) +{ + int i; + + if (bits == 0) + return -1; + i = 32; + if (bits & 0x0000FFFF) + { + bits &= 0x0000FFFF; + i -= 16; + } + if (bits & 0x00FF00FF) + { + bits &= 0x00FF00FF; + i -= 8; + } + if (bits & 0x0F0F0F0F) + { + bits &= 0x0F0F0F0F; + i -= 4; + } + if (bits & 0x33333333) + { + bits &= 0x33333333; + i -= 2; + } + if (bits & 0x55555555) + { + bits &= 0x55555555; + i -= 1; + } + return i; +} +/*- End of function --------------------------------------------------------*/ +#endif + +/*! \brief Bit reverse a byte. + \param data The byte to be reversed. + \return The bit reversed version of data. */ +static __inline__ uint8_t bit_reverse8(uint8_t x) +{ +#if defined(__i386__) || defined(__x86_64__) + /* If multiply is fast */ + return ((x*0x0802U & 0x22110U) | (x*0x8020U & 0x88440U))*0x10101U >> 16; +#else + /* If multiply is slow, but we have a barrel shifter */ + x = (x >> 4) | (x << 4); + x = ((x & 0xCC) >> 2) | ((x & 0x33) << 2); + return ((x & 0xAA) >> 1) | ((x & 0x55) << 1); +#endif +} +/*- End of function --------------------------------------------------------*/ + +/*! \brief Bit reverse a 16 bit word. + \param data The word to be reversed. + \return The bit reversed version of data. */ +uint16_t bit_reverse16(uint16_t data); + +/*! \brief Bit reverse a 32 bit word. + \param data The word to be reversed. + \return The bit reversed version of data. */ +uint32_t bit_reverse32(uint32_t data); + +/*! \brief Bit reverse each of the four bytes in a 32 bit word. + \param data The word to be reversed. + \return The bit reversed version of data. */ +uint32_t bit_reverse_4bytes(uint32_t data); + +/*! \brief Find the number of set bits in a 32 bit word. + \param x The word to be searched. + \return The number of set bits. */ +int one_bits32(uint32_t x); + +/*! \brief Create a mask as wide as the number in a 32 bit word. + \param x The word to be searched. + \return The mask. */ +uint32_t make_mask32(uint32_t x); + +/*! \brief Create a mask as wide as the number in a 16 bit word. + \param x The word to be searched. + \return The mask. */ +uint16_t make_mask16(uint16_t x); + +/*! \brief Find the least significant one in a word, and return a word + with just that bit set. + \param x The word to be searched. + \return The word with the single set bit. */ +static __inline__ uint32_t least_significant_one32(uint32_t x) +{ + return (x & (-(int32_t) x)); +} +/*- End of function --------------------------------------------------------*/ + +/*! \brief Find the most significant one in a word, and return a word + with just that bit set. + \param x The word to be searched. + \return The word with the single set bit. */ +static __inline__ uint32_t most_significant_one32(uint32_t x) +{ +#if defined(__i386__) || defined(__x86_64__) + return 1 << top_bit(x); +#else + x = make_mask32(x); + return (x ^ (x >> 1)); +#endif +} +/*- End of function --------------------------------------------------------*/ + +/*! \brief Find the parity of a byte. + \param x The byte to be checked. + \return 1 for odd, or 0 for even. */ +static __inline__ int parity8(uint8_t x) +{ + x = (x ^ (x >> 4)) & 0x0F; + return (0x6996 >> x) & 1; +} +/*- End of function --------------------------------------------------------*/ + +/*! \brief Find the parity of a 16 bit word. + \param x The word to be checked. + \return 1 for odd, or 0 for even. */ +static __inline__ int parity16(uint16_t x) +{ + x ^= (x >> 8); + x = (x ^ (x >> 4)) & 0x0F; + return (0x6996 >> x) & 1; +} +/*- End of function --------------------------------------------------------*/ + +/*! \brief Find the parity of a 32 bit word. + \param x The word to be checked. + \return 1 for odd, or 0 for even. */ +static __inline__ int parity32(uint32_t x) +{ + x ^= (x >> 16); + x ^= (x >> 8); + x = (x ^ (x >> 4)) & 0x0F; + return (0x6996 >> x) & 1; +} +/*- End of function --------------------------------------------------------*/ + +#ifdef __cplusplus +} +#endif + +#endif +/*- End of file ------------------------------------------------------------*/ |