path: root/src/include/bitstring.i

/*-
 * Copyright (c) 2008-2012 WiredTiger, Inc.
 *
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

/*-
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Paul Vixie.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/sys/sys/bitstring.h,v 1.5 2005/01/07 02:29:23 imp Exp $
 */

				/* byte of the bitstring bit is in */
#define	__bit_byte(bit)	((bit) >> 3)

				/* mask for the bit within its byte */
#define	__bit_mask(bit)	(1 << ((bit) & 0x7))

/*
 * __bitstr_size --
 *	Return the bytes in a bitstring of nbits.
 */
static inline uint32_t
__bitstr_size(uint32_t nbits)
{
	return (((nbits) + 7) >> 3);
}

/*
 * __bit_alloc --
 *	Allocate a bitstring.
 */
static inline int
__bit_alloc(WT_SESSION_IMPL *session, uint32_t nbits, void *retp)
{
	return (__wt_calloc(
	    session, (size_t)__bitstr_size(nbits), sizeof(uint8_t), retp));
}

/*
 * __bit_test --
 *	Test one bit in name.
 */
static inline int
__bit_test(uint8_t *bitf, uint32_t bit)
{
	return (bitf[__bit_byte(bit)] & __bit_mask(bit) ? 1 : 0);
}

/*
 * __bit_set --
 *	Set one bit in name.
 */
static inline void
__bit_set(uint8_t *bitf, uint32_t bit)
{
	bitf[__bit_byte(bit)] |= __bit_mask(bit);
}

/*
 * __bit_clear --
 *	Clear one bit in name.
 */
static inline void
__bit_clear(uint8_t *bitf, uint32_t bit)
{
	bitf[__bit_byte(bit)] &= ~__bit_mask(bit);
}

#ifdef __NOT_CURRENTLY_USED
/*
 * __bit_nclr --
 *	Clear bits start-to-stop in name.
 */
static inline void
__bit_nclr(uint8_t *bitf, uint32_t start, uint32_t stop)
{
	uint32_t startbyte, stopbyte;

	startbyte = __bit_byte(start);
	stopbyte = __bit_byte(stop);

	if (startbyte == stopbyte)
		bitf[startbyte] &=
		    ((0xff >> (8 - (start & 0x7))) |
		    (0xff << ((stop & 0x7) + 1)));
	else {
		bitf[startbyte] &= 0xff >> (8 - (start & 0x7));
		while (++startbyte < stopbyte)
			bitf[startbyte] = 0;
		bitf[stopbyte] &= 0xff << ((stop & 0x7) + 1);
	}
}
#endif

/*
 * __bit_nset --
 *	Set bits start-to-stop in name.
 */
static inline void
__bit_nset(uint8_t *bitf, uint32_t start, uint32_t stop)
{
	uint32_t startbyte, stopbyte;

	startbyte = __bit_byte(start);
	stopbyte = __bit_byte(stop);
	if (startbyte == stopbyte)
		bitf[startbyte] |=
		    ((0xff << (start & 0x7)) & (0xff >> (7 - (stop & 0x7))));
	else {
		bitf[startbyte] |= 0xff << (start & 0x7);
		while (++startbyte < stopbyte)
			bitf[startbyte] = 0xff;
		bitf[stopbyte] |= 0xff >> (7 - (stop & 0x7));
	}
}

/*
 * __bit_ffc --
 *	Find first clear bit in name, return 0 on success, -1 on no bit clear.
 */
static inline int
__bit_ffc(uint8_t *bitf, uint32_t nbits, uint32_t *retp)
{
	uint8_t lb;
	uint32_t byte, stopbyte, value;

	value = 0;              /* -Wuninitialized */

	if (nbits == 0)
		return (-1);

	for (byte = 0,
	    stopbyte = __bit_byte(nbits - 1); byte <= stopbyte; ++byte)
		if (bitf[byte] != 0xff) {
			value = byte << 3;
			for (lb = bitf[byte]; lb & 0x01; ++value, lb >>= 1)
				;
			break;
		}

	if (byte > stopbyte || value >= nbits)
		return (-1);

	*retp = value;
	return (0);
}

#ifdef __NOT_CURRENTLY_USED
/*
 * __bit_ffs --
 *	Find first set bit in name, return 0 on success, -1 on no bit set.
 */
static inline int
__bit_ffs(uint8_t *bitf, uint32_t nbits, uint32_t *retp)
{
	uint8_t lb;
	uint32_t byte, stopbyte, value;

	if (nbits == 0)
		return (-1);

	for (byte = 0,
	    stopbyte = __bit_byte(nbits - 1); byte <= stopbyte; ++byte)
		if (bitf[byte] != 0) {
			value = byte << 3;
			for (lb = bitf[byte]; !(lb & 0x01); ++value, lb >>= 1)
				;
			break;
		}

	if (byte > stopbyte || value >= nbits)
		return (-1);

	*retp = value;
	return (0);
}
#endif

/*
 * __bit_getv --
 *	Return a fixed-length column store bit-field value.
 */
static inline uint8_t
__bit_getv(uint8_t *bitf, uint32_t entry, uint8_t width)
{
	uint8_t value;
	uint32_t bit;

#define	__BIT_GET(len, mask)						\
	case len:							\
		if (__bit_test(bitf, bit))				\
			value |= mask;					\
		++bit							\
		/* FALLTHROUGH */

	value = 0;
	bit = entry * width;

	/*
	 * Fast-path single bytes, do repeated tests for the rest: we could
	 * slice-and-dice instead, but the compiler is probably going to do
	 * a better job than I will.
	 */
	switch (width) {
	case 8:
		return (bitf[__bit_byte(bit)]);
	__BIT_GET(7, 0x40);
	__BIT_GET(6, 0x20);
	__BIT_GET(5, 0x10);
	__BIT_GET(4, 0x08);
	__BIT_GET(3, 0x04);
	__BIT_GET(2, 0x02);
	__BIT_GET(1, 0x01);
	}
	return (value);
}

/*
 * __bit_getv_recno --
 *	Return a record number's bit-field value.
 */
static inline uint8_t
__bit_getv_recno(WT_PAGE *page, uint64_t recno, uint8_t width)
{
	return (__bit_getv(page->u.col_fix.bitf,
	    (uint32_t)(recno - page->u.col_fix.recno), width));
}

/*
 * __bit_setv --
 *	Set a fixed-length column store bit-field value.
 */
static inline void
__bit_setv(uint8_t *bitf, uint32_t entry, uint8_t width, uint8_t value)
{
	uint32_t bit;

#define	__BIT_SET(len, mask)						\
	case len:							\
		if (value & (mask))					\
			__bit_set(bitf, bit);				\
		else							\
			__bit_clear(bitf, bit);				\
		++bit							\
		/* FALLTHROUGH */

	bit = entry * width;

	/*
	 * Fast-path single bytes, do repeated tests for the rest: we could
	 * slice-and-dice instead, but the compiler is probably going to do
	 * a better job than I will.
	 */
	switch (width) {
	case 8:
		bitf[__bit_byte(bit)] = value;
		return;
	__BIT_SET(7, 0x40);
	__BIT_SET(6, 0x20);
	__BIT_SET(5, 0x10);
	__BIT_SET(4, 0x08);
	__BIT_SET(3, 0x04);
	__BIT_SET(2, 0x02);
	__BIT_SET(1, 0x01);
	}
}

/*
 * __bit_setv_recno --
 *	Set a record number's bit-field value.
 */
static inline void
__bit_setv_recno(WT_PAGE *page, uint64_t recno, uint8_t width, uint8_t value)
{
	return (__bit_setv(page->u.col_fix.bitf,
	    (uint32_t)(recno - page->u.col_fix.recno), width, value));
}