Staging: echo: remove bit_operations.h

/*

 * 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.

 */

/*! \file */

#if !defined(_BIT_OPERATIONS_H_)

#define _BIT_OPERATIONS_H_

#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;

}

/*! \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;

}

#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;

}

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;

}

#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

}

/*! \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);

}

/*! \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

}

/*! \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;

}

/*! \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;

}

/*! \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;

}

#endif

/*- End of file ------------------------------------------------------------*/