linux/lib/lz4/lz4defs.h

#ifndef __LZ4DEFS_H__
#define __LZ4DEFS_H__

/*
 * lz4defs.h -- common and architecture specific defines for the kernel usage

 * LZ4 - Fast LZ compression algorithm
 * Copyright (C) 2011-2016, Yann Collet.
 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *	* Redistributions of source code must retain the above copyright
 *	  notice, this list of conditions and the following disclaimer.
 *	* 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.
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 * OWNER 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.
 * You can contact the author at :
 *	- LZ4 homepage : http://www.lz4.org
 *	- LZ4 source repository : https://github.com/lz4/lz4
 *
 *	Changed for kernel usage by:
 *	Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
 */

#include <asm/unaligned.h>
#include <linux/string.h>	 /* memset, memcpy */

#define FORCE_INLINE __always_inline

/*-************************************
 *	Basic Types
 **************************************/
#include <linux/types.h>

typedef	uint8_t BYTE;
typedef uint16_t U16;
typedef uint32_t U32;
typedef	int32_t S32;
typedef uint64_t U64;
typedef uintptr_t uptrval;

/*-************************************
 *	Architecture specifics
 **************************************/
#if defined(CONFIG_64BIT)
#define LZ4_ARCH64 1
#else
#define LZ4_ARCH64 0
#endif

#if defined(__LITTLE_ENDIAN)
#define LZ4_LITTLE_ENDIAN 1
#else
#define LZ4_LITTLE_ENDIAN 0
#endif

/*-************************************
 *	Constants
 **************************************/
#define MINMATCH 4

#define WILDCOPYLENGTH 8
#define LASTLITERALS 5
#define MFLIMIT (WILDCOPYLENGTH + MINMATCH)
/*
 * ensure it's possible to write 2 x wildcopyLength
 * without overflowing output buffer
 */
#define MATCH_SAFEGUARD_DISTANCE  ((2 * WILDCOPYLENGTH) - MINMATCH)

/* Increase this value ==> compression run slower on incompressible data */
#define LZ4_SKIPTRIGGER 6

#define HASH_UNIT sizeof(size_t)

#define KB (1 << 10)
#define MB (1 << 20)
#define GB (1U << 30)

#define MAXD_LOG 16
#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
#define STEPSIZE sizeof(size_t)

#define ML_BITS	4
#define ML_MASK	((1U << ML_BITS) - 1)
#define RUN_BITS (8 - ML_BITS)
#define RUN_MASK ((1U << RUN_BITS) - 1)

/*-************************************
 *	Reading and writing into memory
 **************************************/
static FORCE_INLINE U16 LZ4_read16(const void *ptr)
{
	return get_unaligned((const U16 *)ptr);
}

static FORCE_INLINE U32 LZ4_read32(const void *ptr)
{
	return get_unaligned((const U32 *)ptr);
}

static FORCE_INLINE size_t LZ4_read_ARCH(const void *ptr)
{
	return get_unaligned((const size_t *)ptr);
}

static FORCE_INLINE void LZ4_write16(void *memPtr, U16 value)
{
	put_unaligned(value, (U16 *)memPtr);
}

static FORCE_INLINE void LZ4_write32(void *memPtr, U32 value)
{
	put_unaligned(value, (U32 *)memPtr);
}

static FORCE_INLINE U16 LZ4_readLE16(const void *memPtr)
{
	return get_unaligned_le16(memPtr);
}

static FORCE_INLINE void LZ4_writeLE16(void *memPtr, U16 value)
{
	return put_unaligned_le16(value, memPtr);
}

/*
 * LZ4 relies on memcpy with a constant size being inlined. In freestanding
 * environments, the compiler can't assume the implementation of memcpy() is
 * standard compliant, so apply its specialized memcpy() inlining logic. When
 * possible, use __builtin_memcpy() to tell the compiler to analyze memcpy()
 * as-if it were standard compliant, so it can inline it in freestanding
 * environments. This is needed when decompressing the Linux Kernel, for example.
 */
#define LZ4_memcpy(dst, src, size) __builtin_memcpy(dst, src, size)

static FORCE_INLINE void LZ4_copy8(void *dst, const void *src)
{
#if LZ4_ARCH64
	U64 a = get_unaligned((const U64 *)src);

	put_unaligned(a, (U64 *)dst);
#else
	U32 a = get_unaligned((const U32 *)src);
	U32 b = get_unaligned((const U32 *)src + 1);

	put_unaligned(a, (U32 *)dst);
	put_unaligned(b, (U32 *)dst + 1);
#endif
}

/*
 * customized variant of memcpy,
 * which can overwrite up to 7 bytes beyond dstEnd
 */
static FORCE_INLINE void LZ4_wildCopy(void *dstPtr,
	const void *srcPtr, void *dstEnd)
{
	BYTE *d = (BYTE *)dstPtr;
	const BYTE *s = (const BYTE *)srcPtr;
	BYTE *const e = (BYTE *)dstEnd;

	do {
		LZ4_copy8(d, s);
		d += 8;
		s += 8;
	} while (d < e);
}

static FORCE_INLINE unsigned int LZ4_NbCommonBytes(register size_t val)
{
#if LZ4_LITTLE_ENDIAN
	return __ffs(val) >> 3;
#else
	return (BITS_PER_LONG - 1 - __fls(val)) >> 3;
#endif
}

static FORCE_INLINE unsigned int LZ4_count(
	const BYTE *pIn,
	const BYTE *pMatch,
	const BYTE *pInLimit)
{
	const BYTE *const pStart = pIn;

	while (likely(pIn < pInLimit - (STEPSIZE - 1))) {
		size_t const diff = LZ4_read_ARCH(pMatch) ^ LZ4_read_ARCH(pIn);

		if (!diff) {
			pIn += STEPSIZE;
			pMatch += STEPSIZE;
			continue;
		}

		pIn += LZ4_NbCommonBytes(diff);

		return (unsigned int)(pIn - pStart);
	}

#if LZ4_ARCH64
	if ((pIn < (pInLimit - 3))
		&& (LZ4_read32(pMatch) == LZ4_read32(pIn))) {
		pIn += 4;
		pMatch += 4;
	}
#endif

	if ((pIn < (pInLimit - 1))
		&& (LZ4_read16(pMatch) == LZ4_read16(pIn))) {
		pIn += 2;
		pMatch += 2;
	}

	if ((pIn < pInLimit) && (*pMatch == *pIn))
		pIn++;

	return (unsigned int)(pIn - pStart);
}

typedef enum { noLimit = 0, limitedOutput = 1 } limitedOutput_directive;
typedef enum { byPtr, byU32, byU16 } tableType_t;

typedef enum { noDict = 0, withPrefix64k, usingExtDict } dict_directive;
typedef enum { noDictIssue = 0, dictSmall } dictIssue_directive;

typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
typedef enum { decode_full_block = 0, partial_decode = 1 } earlyEnd_directive;

#define LZ4_STATIC_ASSERT(c)	BUILD_BUG_ON(!(c))

#endif