FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/module/zstd/lib/common/mem.h

     /*
      * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc.
      * All rights reserved.
      *
      * This source code is licensed under both the BSD-style license (found in the
      * LICENSE file in the root directory of this source tree) and the GPLv2 (found
      * in the COPYING file in the root directory of this source tree).
      * You may select, at your option, one of the above-listed licenses.
      */
    
    #ifndef MEM_H_MODULE
    #define MEM_H_MODULE
    
    #if defined (__cplusplus)
    extern "C" {
    #endif
    
    /*-****************************************
    *  Dependencies
    ******************************************/
    #include <stddef.h>     /* size_t, ptrdiff_t */
    #include <string.h>     /* memcpy */
    
    
    /*-****************************************
    *  Compiler specifics
    ******************************************/
    #if defined(_MSC_VER)   /* Visual Studio */
    #   include <stdlib.h>  /* _byteswap_ulong */
    #   include <intrin.h>  /* _byteswap_* */
    #endif
    #if defined(__GNUC__)
    #  define MEM_STATIC static __inline __attribute__((unused))
    #elif defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
    #  define MEM_STATIC static inline
    #elif defined(_MSC_VER)
    #  define MEM_STATIC static __inline
    #else
    #  define MEM_STATIC static  /* this version may generate warnings for unused static functions; disable the relevant warning */
    #endif
    
    #ifndef __has_builtin
    #  define __has_builtin(x) 0  /* compat. with non-clang compilers */
    #endif
    
    /* code only tested on 32 and 64 bits systems */
    #define MEM_STATIC_ASSERT(c)   { enum { MEM_static_assert = 1/(int)(!!(c)) }; }
    MEM_STATIC void MEM_check(void) { MEM_STATIC_ASSERT((sizeof(size_t)==4) || (sizeof(size_t)==8)); }
    
    /* detects whether we are being compiled under msan */
    #if defined (__has_feature)
    #  if __has_feature(memory_sanitizer)
    #    define MEMORY_SANITIZER 1
    #  endif
    #endif
    
    #if defined (MEMORY_SANITIZER)
    /* Not all platforms that support msan provide sanitizers/msan_interface.h.
     * We therefore declare the functions we need ourselves, rather than trying to
     * include the header file... */
    
    #include <stdint.h> /* intptr_t */
    
    /* Make memory region fully initialized (without changing its contents). */
    void __msan_unpoison(const volatile void *a, size_t size);
    
    /* Make memory region fully uninitialized (without changing its contents).
       This is a legacy interface that does not update origin information. Use
       __msan_allocated_memory() instead. */
    void __msan_poison(const volatile void *a, size_t size);
    
    /* Returns the offset of the first (at least partially) poisoned byte in the
       memory range, or -1 if the whole range is good. */
    intptr_t __msan_test_shadow(const volatile void *x, size_t size);
    #endif
    
    /* detects whether we are being compiled under asan */
    #if defined (ZFS_ASAN_ENABLED)
    #  define ADDRESS_SANITIZER 1
    #  define ZSTD_ASAN_DONT_POISON_WORKSPACE
    #endif
    
    #if defined (ADDRESS_SANITIZER)
    /* Not all platforms that support asan provide sanitizers/asan_interface.h.
     * We therefore declare the functions we need ourselves, rather than trying to
     * include the header file... */
    
    /**
     * Marks a memory region (<c>[addr, addr+size)</c>) as unaddressable.
     *
     * This memory must be previously allocated by your program. Instrumented
     * code is forbidden from accessing addresses in this region until it is
     * unpoisoned. This function is not guaranteed to poison the entire region -
     * it could poison only a subregion of <c>[addr, addr+size)</c> due to ASan
     * alignment restrictions.
     *
     * \note This function is not thread-safe because no two threads can poison or
     * unpoison memory in the same memory region simultaneously.
     *
    * \param addr Start of memory region.
    * \param size Size of memory region. */
   void __asan_poison_memory_region(void const volatile *addr, size_t size);
   
   /**
    * Marks a memory region (<c>[addr, addr+size)</c>) as addressable.
    *
    * This memory must be previously allocated by your program. Accessing
    * addresses in this region is allowed until this region is poisoned again.
    * This function could unpoison a super-region of <c>[addr, addr+size)</c> due
    * to ASan alignment restrictions.
    *
    * \note This function is not thread-safe because no two threads can
    * poison or unpoison memory in the same memory region simultaneously.
    *
    * \param addr Start of memory region.
    * \param size Size of memory region. */
   void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
   #endif
   
   
   /*-**************************************************************
   *  Basic Types
   *****************************************************************/
   #if  !defined (__VMS) && (defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) )
   # include <stdint.h>
     typedef   uint8_t BYTE;
     typedef  uint16_t U16;
     typedef   int16_t S16;
     typedef  uint32_t U32;
     typedef   int32_t S32;
     typedef  uint64_t U64;
     typedef   int64_t S64;
   #else
   # include <limits.h>
   #if CHAR_BIT != 8
   #  error "this implementation requires char to be exactly 8-bit type"
   #endif
     typedef unsigned char      BYTE;
   #if USHRT_MAX != 65535
   #  error "this implementation requires short to be exactly 16-bit type"
   #endif
     typedef unsigned short      U16;
     typedef   signed short      S16;
   #if UINT_MAX != 4294967295
   #  error "this implementation requires int to be exactly 32-bit type"
   #endif
     typedef unsigned int        U32;
     typedef   signed int        S32;
   /* note : there are no limits defined for long long type in C90.
    * limits exist in C99, however, in such case, <stdint.h> is preferred */
     typedef unsigned long long  U64;
     typedef   signed long long  S64;
   #endif
   
   
   /*-**************************************************************
   *  Memory I/O
   *****************************************************************/
   /* MEM_FORCE_MEMORY_ACCESS :
    * By default, access to unaligned memory is controlled by `memcpy()`, which is safe and portable.
    * Unfortunately, on some target/compiler combinations, the generated assembly is sub-optimal.
    * The below switch allow to select different access method for improved performance.
    * Method 0 (default) : use `memcpy()`. Safe and portable.
    * Method 1 : `__packed` statement. It depends on compiler extension (i.e., not portable).
    *            This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`.
    * Method 2 : direct access. This method is portable but violate C standard.
    *            It can generate buggy code on targets depending on alignment.
    *            In some circumstances, it's the only known way to get the most performance (i.e. GCC + ARMv6)
    * See http://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details.
    * Prefer these methods in priority order (0 > 1 > 2)
    */
   #ifndef MEM_FORCE_MEMORY_ACCESS   /* can be defined externally, on command line for example */
   #  if defined(__GNUC__) && ( defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__) )
   #    define MEM_FORCE_MEMORY_ACCESS 2
   #  elif defined(__INTEL_COMPILER) || defined(__GNUC__) || defined(__ICCARM__)
   #    define MEM_FORCE_MEMORY_ACCESS 1
   #  endif
   #endif
   
   MEM_STATIC unsigned MEM_32bits(void) { return sizeof(size_t)==4; }
   MEM_STATIC unsigned MEM_64bits(void) { return sizeof(size_t)==8; }
   
   MEM_STATIC unsigned MEM_isLittleEndian(void)
   {
       const union { U32 u; BYTE c[4]; } one = { 1 };   /* don't use static : performance detrimental  */
       return one.c[0];
   }
   
   #if defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==2)
   
   /* violates C standard, by lying on structure alignment.
   Only use if no other choice to achieve best performance on target platform */
   MEM_STATIC U16 MEM_read16(const void* memPtr) { return *(const U16*) memPtr; }
   MEM_STATIC U32 MEM_read32(const void* memPtr) { return *(const U32*) memPtr; }
   MEM_STATIC U64 MEM_read64(const void* memPtr) { return *(const U64*) memPtr; }
   MEM_STATIC size_t MEM_readST(const void* memPtr) { return *(const size_t*) memPtr; }
   
   MEM_STATIC void MEM_write16(void* memPtr, U16 value) { *(U16*)memPtr = value; }
   MEM_STATIC void MEM_write32(void* memPtr, U32 value) { *(U32*)memPtr = value; }
   MEM_STATIC void MEM_write64(void* memPtr, U64 value) { *(U64*)memPtr = value; }
   
   #elif defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==1)
   
   /* __pack instructions are safer, but compiler specific, hence potentially problematic for some compilers */
   /* currently only defined for gcc and icc */
   #if defined(_MSC_VER) || (defined(__INTEL_COMPILER) && defined(WIN32))
       __pragma( pack(push, 1) )
       typedef struct { U16 v; } unalign16;
       typedef struct { U32 v; } unalign32;
       typedef struct { U64 v; } unalign64;
       typedef struct { size_t v; } unalignArch;
       __pragma( pack(pop) )
   #else
       typedef struct { U16 v; } __attribute__((packed)) unalign16;
       typedef struct { U32 v; } __attribute__((packed)) unalign32;
       typedef struct { U64 v; } __attribute__((packed)) unalign64;
       typedef struct { size_t v; } __attribute__((packed)) unalignArch;
   #endif
   
   MEM_STATIC U16 MEM_read16(const void* ptr) { return ((const unalign16*)ptr)->v; }
   MEM_STATIC U32 MEM_read32(const void* ptr) { return ((const unalign32*)ptr)->v; }
   MEM_STATIC U64 MEM_read64(const void* ptr) { return ((const unalign64*)ptr)->v; }
   MEM_STATIC size_t MEM_readST(const void* ptr) { return ((const unalignArch*)ptr)->v; }
   
   MEM_STATIC void MEM_write16(void* memPtr, U16 value) { ((unalign16*)memPtr)->v = value; }
   MEM_STATIC void MEM_write32(void* memPtr, U32 value) { ((unalign32*)memPtr)->v = value; }
   MEM_STATIC void MEM_write64(void* memPtr, U64 value) { ((unalign64*)memPtr)->v = value; }
   
   #else
   
   /* default method, safe and standard.
      can sometimes prove slower */
   
   MEM_STATIC U16 MEM_read16(const void* memPtr)
   {
       U16 val; memcpy(&val, memPtr, sizeof(val)); return val;
   }
   
   MEM_STATIC U32 MEM_read32(const void* memPtr)
   {
       U32 val; memcpy(&val, memPtr, sizeof(val)); return val;
   }
   
   MEM_STATIC U64 MEM_read64(const void* memPtr)
   {
       U64 val; memcpy(&val, memPtr, sizeof(val)); return val;
   }
   
   MEM_STATIC size_t MEM_readST(const void* memPtr)
   {
       size_t val; memcpy(&val, memPtr, sizeof(val)); return val;
   }
   
   MEM_STATIC void MEM_write16(void* memPtr, U16 value)
   {
       memcpy(memPtr, &value, sizeof(value));
   }
   
   MEM_STATIC void MEM_write32(void* memPtr, U32 value)
   {
       memcpy(memPtr, &value, sizeof(value));
   }
   
   MEM_STATIC void MEM_write64(void* memPtr, U64 value)
   {
       memcpy(memPtr, &value, sizeof(value));
   }
   
   #endif /* MEM_FORCE_MEMORY_ACCESS */
   
   MEM_STATIC U32 MEM_swap32(U32 in)
   {
   #if defined(_MSC_VER)     /* Visual Studio */
       return _byteswap_ulong(in);
   #elif (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
     || (defined(__clang__) && __has_builtin(__builtin_bswap32))
       return __builtin_bswap32(in);
   #else
       return  ((in << 24) & 0xff000000 ) |
               ((in <<  8) & 0x00ff0000 ) |
               ((in >>  8) & 0x0000ff00 ) |
               ((in >> 24) & 0x000000ff );
   #endif
   }
   
   MEM_STATIC U64 MEM_swap64(U64 in)
   {
   #if defined(_MSC_VER)     /* Visual Studio */
       return _byteswap_uint64(in);
   #elif (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
     || (defined(__clang__) && __has_builtin(__builtin_bswap64))
       return __builtin_bswap64(in);
   #else
       return  ((in << 56) & 0xff00000000000000ULL) |
               ((in << 40) & 0x00ff000000000000ULL) |
               ((in << 24) & 0x0000ff0000000000ULL) |
               ((in << 8)  & 0x000000ff00000000ULL) |
               ((in >> 8)  & 0x00000000ff000000ULL) |
               ((in >> 24) & 0x0000000000ff0000ULL) |
               ((in >> 40) & 0x000000000000ff00ULL) |
               ((in >> 56) & 0x00000000000000ffULL);
   #endif
   }
   
   MEM_STATIC size_t MEM_swapST(size_t in)
   {
       if (MEM_32bits())
           return (size_t)MEM_swap32((U32)in);
       else
           return (size_t)MEM_swap64((U64)in);
   }
   
   /*=== Little endian r/w ===*/
   
   MEM_STATIC U16 MEM_readLE16(const void* memPtr)
   {
       if (MEM_isLittleEndian())
           return MEM_read16(memPtr);
       else {
           const BYTE* p = (const BYTE*)memPtr;
           return (U16)(p[0] + (p[1]<<8));
       }
   }
   
   MEM_STATIC void MEM_writeLE16(void* memPtr, U16 val)
   {
       if (MEM_isLittleEndian()) {
           MEM_write16(memPtr, val);
       } else {
           BYTE* p = (BYTE*)memPtr;
           p[0] = (BYTE)val;
           p[1] = (BYTE)(val>>8);
       }
   }
   
   MEM_STATIC U32 MEM_readLE24(const void* memPtr)
   {
       return MEM_readLE16(memPtr) + (((const BYTE*)memPtr)[2] << 16);
   }
   
   MEM_STATIC void MEM_writeLE24(void* memPtr, U32 val)
   {
       MEM_writeLE16(memPtr, (U16)val);
       ((BYTE*)memPtr)[2] = (BYTE)(val>>16);
   }
   
   MEM_STATIC U32 MEM_readLE32(const void* memPtr)
   {
       if (MEM_isLittleEndian())
           return MEM_read32(memPtr);
       else
           return MEM_swap32(MEM_read32(memPtr));
   }
   
   MEM_STATIC void MEM_writeLE32(void* memPtr, U32 val32)
   {
       if (MEM_isLittleEndian())
           MEM_write32(memPtr, val32);
       else
           MEM_write32(memPtr, MEM_swap32(val32));
   }
   
   MEM_STATIC U64 MEM_readLE64(const void* memPtr)
   {
       if (MEM_isLittleEndian())
           return MEM_read64(memPtr);
       else
           return MEM_swap64(MEM_read64(memPtr));
   }
   
   MEM_STATIC void MEM_writeLE64(void* memPtr, U64 val64)
   {
       if (MEM_isLittleEndian())
           MEM_write64(memPtr, val64);
       else
           MEM_write64(memPtr, MEM_swap64(val64));
   }
   
   MEM_STATIC size_t MEM_readLEST(const void* memPtr)
   {
       if (MEM_32bits())
           return (size_t)MEM_readLE32(memPtr);
       else
           return (size_t)MEM_readLE64(memPtr);
   }
   
   MEM_STATIC void MEM_writeLEST(void* memPtr, size_t val)
   {
       if (MEM_32bits())
           MEM_writeLE32(memPtr, (U32)val);
       else
           MEM_writeLE64(memPtr, (U64)val);
   }
   
   /*=== Big endian r/w ===*/
   
   MEM_STATIC U32 MEM_readBE32(const void* memPtr)
   {
       if (MEM_isLittleEndian())
           return MEM_swap32(MEM_read32(memPtr));
       else
           return MEM_read32(memPtr);
   }
   
   MEM_STATIC void MEM_writeBE32(void* memPtr, U32 val32)
   {
       if (MEM_isLittleEndian())
           MEM_write32(memPtr, MEM_swap32(val32));
       else
           MEM_write32(memPtr, val32);
   }
   
   MEM_STATIC U64 MEM_readBE64(const void* memPtr)
   {
       if (MEM_isLittleEndian())
           return MEM_swap64(MEM_read64(memPtr));
       else
           return MEM_read64(memPtr);
   }
   
   MEM_STATIC void MEM_writeBE64(void* memPtr, U64 val64)
   {
       if (MEM_isLittleEndian())
           MEM_write64(memPtr, MEM_swap64(val64));
       else
           MEM_write64(memPtr, val64);
   }
   
   MEM_STATIC size_t MEM_readBEST(const void* memPtr)
   {
       if (MEM_32bits())
           return (size_t)MEM_readBE32(memPtr);
       else
           return (size_t)MEM_readBE64(memPtr);
   }
   
   MEM_STATIC void MEM_writeBEST(void* memPtr, size_t val)
   {
       if (MEM_32bits())
           MEM_writeBE32(memPtr, (U32)val);
       else
           MEM_writeBE64(memPtr, (U64)val);
   }
   
   
   #if defined (__cplusplus)
   }
   #endif
   
   #endif /* MEM_H_MODULE */

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