/********************************************************************
** File: memcpy.c
**
** Copyright (C) 1999-2010 Daniel Vik
**
** This software is provided 'as-is', without any express or implied
** warranty. In no event will the authors be held liable for any
** damages arising from the use of this software.
** Permission is granted to anyone to use this software for any
** purpose, including commercial applications, and to alter it and
** redistribute it freely, subject to the following restrictions:
**
** 1. The origin of this software must not be misrepresented; you
** must not claim that you wrote the original software. If you
** use this software in a product, an acknowledgment in the
** use this software in a product, an acknowledgment in the
** product documentation would be appreciated but is not
** required.
**
** 2. Altered source versions must be plainly marked as such, and
** must not be misrepresented as being the original software.
**
** 3. This notice may not be removed or altered from any source
** distribution.
**
**
** Description: Implementation of the standard library function memcpy.
** This implementation of memcpy() is ANSI-C89 compatible.
**
** The following configuration options can be set:
**
** LITTLE_ENDIAN - Uses processor with little endian
** addressing. Default is big endian.
**
** PRE_INC_PTRS - Use pre increment of pointers.
** Default is post increment of
** pointers.
**
** INDEXED_COPY - Copying data using array indexing.
** Using this option, disables the
** PRE_INC_PTRS option.
**
** MEMCPY_64BIT - Compiles memcpy for 64 bit
** architectures
**
**
** Best Settings:
**
** Intel x86: LITTLE_ENDIAN and INDEXED_COPY
**
*******************************************************************/
/********************************************************************
** Configuration definitions.
*******************************************************************/
#define LITTLE_ENDIAN
#define INDEXED_COPY
#define MEMCPY_64BIT
/********************************************************************
** Includes for size_t definition
*******************************************************************/
#include <stddef.h>
/********************************************************************
** Typedefs
*******************************************************************/
typedef unsigned char UInt8;
typedef unsigned short UInt16;
typedef unsigned int UInt32;
#ifdef _WIN32
typedef unsigned __int64 UInt64;
#else
typedef unsigned long long UInt64;
#endif
#ifdef MEMCPY_64BIT
typedef UInt64 UIntN;
#define TYPE_WIDTH 8L
#else
typedef UInt32 UIntN;
#define TYPE_WIDTH 4L
#endif
/********************************************************************
** Remove definitions when INDEXED_COPY is defined.
*******************************************************************/
#if defined(INDEXED_COPY)
#if defined(PRE_INC_PTRS)
#undef PRE_INC_PTRS
#endif /*PRE_INC_PTRS*/
#endif /*INDEXED_COPY*/
/********************************************************************
** Definitions for pre and post increment of pointers.
*******************************************************************/
#if defined(PRE_INC_PTRS)
#define START_VAL(x) (x)--
#define INC_VAL(x) *++(x)
#define CAST_TO_U8(p, o) ((UInt8 *)p + o + TYPE_WIDTH)
#define WHILE_DEST_BREAK (TYPE_WIDTH - 1)
#define PRE_LOOP_ADJUST -(TYPE_WIDTH - 1)
#define PRE_SWITCH_ADJUST +1
#else /*PRE_INC_PTRS*/
#define START_VAL(x)
#define INC_VAL(x) *(x)++
#define CAST_TO_U8(p, o) ((UInt8 *)p + o)
#define WHILE_DEST_BREAK 0
#define PRE_LOOP_ADJUST
#define PRE_SWITCH_ADJUST
#endif /*PRE_INC_PTRS*/
/********************************************************************
** Definitions for endians
*******************************************************************/
#if defined(LITTLE_ENDIAN)
#define SHL >>
#define SHR <<
#else /* LITTLE_ENDIAN */
#define SHL <<
#define SHR >>
#endif /* LITTLE_ENDIAN */
/********************************************************************
** Macros for copying words of different alignment.
** Uses incremening pointers.
*******************************************************************/
#define CP_INCR() \
{ \
INC_VAL(dstN) = INC_VAL(srcN); \
}
#define CP_INCR_SH(shl, shr) \
{ \
dstWord = srcWord SHL shl; \
srcWord = INC_VAL(srcN); \
dstWord |= srcWord SHR shr; \
INC_VAL(dstN) = dstWord; \
}
/********************************************************************
** Macros for copying words of different alignment.
** Uses array indexes.
*******************************************************************/
#define CP_INDEX(idx) \
{ \
dstN[idx] = srcN[idx]; \
}
#define CP_INDEX_SH(x, shl, shr) \
{ \
dstWord = srcWord SHL shl; \
srcWord = srcN[x]; \
dstWord |= srcWord SHR shr; \
dstN[x] = dstWord; \
}
/********************************************************************
** Macros for copying words of different alignment.
** Uses incremening pointers or array indexes depending on
** configuration.
*******************************************************************/
#if defined(INDEXED_COPY)
#define CP(idx) CP_INDEX(idx)
#define CP_SH(idx, shl, shr) CP_INDEX_SH(idx, shl, shr)
#define INC_INDEX(p, o) ((p) += (o))
#else /* INDEXED_COPY */
#define CP(idx) CP_INCR()
#define CP_SH(idx, shl, shr) CP_INCR_SH(shl, shr)
#define INC_INDEX(p, o)
#endif /* INDEXED_COPY */
#define COPY_REMAINING(count) \
{ \
START_VAL(dst8); \
START_VAL(src8); \
\
switch (count) { \
case 7: INC_VAL(dst8) = INC_VAL(src8); \
case 6: INC_VAL(dst8) = INC_VAL(src8); \
case 5: INC_VAL(dst8) = INC_VAL(src8); \
case 4: INC_VAL(dst8) = INC_VAL(src8); \
case 3: INC_VAL(dst8) = INC_VAL(src8); \
case 2: INC_VAL(dst8) = INC_VAL(src8); \
case 1: INC_VAL(dst8) = INC_VAL(src8); \
case 0: \
default: break; \
} \
}
#define COPY_NO_SHIFT() \
{ \
UIntN *dstN = (UIntN *)(dst8 PRE_LOOP_ADJUST); \
UIntN *srcN = (UIntN *)(src8 PRE_LOOP_ADJUST); \
size_t length = count / TYPE_WIDTH; \
\
while (length & 7) { \
CP_INCR(); \
length--; \
} \
\
length /= 8; \
\
while (length--) { \
CP(0); \
CP(1); \
CP(2); \
CP(3); \
CP(4); \
CP(5); \
CP(6); \
CP(7); \
\
INC_INDEX(dstN, 8); \
INC_INDEX(srcN, 8); \
} \
\
src8 = CAST_TO_U8(srcN, 0); \
dst8 = CAST_TO_U8(dstN, 0); \
\
COPY_REMAINING(count &(TYPE_WIDTH - 1)); \
\
return dest; \
}
#define COPY_SHIFT(shift) \
{ \
UIntN *dstN = (UIntN *)((((UIntN)dst8)PRE_LOOP_ADJUST) & ~(TYPE_WIDTH - 1)); \
UIntN *srcN = (UIntN *)((((UIntN)src8)PRE_LOOP_ADJUST) & ~(TYPE_WIDTH - 1)); \
size_t length = count / TYPE_WIDTH; \
UIntN srcWord = INC_VAL(srcN); \
UIntN dstWord; \
\
while (length & 7) { \
CP_INCR_SH(8 * shift, 8 * (TYPE_WIDTH - shift)); \
length--; \
} \
\
length /= 8; \
\
while (length--) { \
CP_SH(0, 8 * shift, 8 * (TYPE_WIDTH - shift)); \
CP_SH(1, 8 * shift, 8 * (TYPE_WIDTH - shift)); \
CP_SH(2, 8 * shift, 8 * (TYPE_WIDTH - shift)); \
CP_SH(3, 8 * shift, 8 * (TYPE_WIDTH - shift)); \
CP_SH(4, 8 * shift, 8 * (TYPE_WIDTH - shift)); \
CP_SH(5, 8 * shift, 8 * (TYPE_WIDTH - shift)); \
CP_SH(6, 8 * shift, 8 * (TYPE_WIDTH - shift)); \
CP_SH(7, 8 * shift, 8 * (TYPE_WIDTH - shift)); \
\
INC_INDEX(dstN, 8); \
INC_INDEX(srcN, 8); \
} \
\
src8 = CAST_TO_U8(srcN, (shift - TYPE_WIDTH)); \
dst8 = CAST_TO_U8(dstN, 0); \
\
COPY_REMAINING(count &(TYPE_WIDTH - 1)); \
\
return dest; \
}
/********************************************************************
**
** void *memcpy(void *dest, const void *src, size_t count)
**
** Args: dest - pointer to destination buffer
** src - pointer to source buffer
** count - number of bytes to copy
**
** Return: A pointer to destination buffer
**
** Purpose: Copies count bytes from src to dest.
** No overlap check is performed.
**
*******************************************************************/
void *memcpy(void *dest, const void *src, size_t count) {
UInt8 *dst8 = (UInt8 *)dest;
UInt8 *src8 = (UInt8 *)src;
if (count < 8) {
COPY_REMAINING(count);
return dest;
}
START_VAL(dst8);
START_VAL(src8);
while (((UIntN)dst8 & (TYPE_WIDTH - 1)) != WHILE_DEST_BREAK) {
INC_VAL(dst8) = INC_VAL(src8);
count--;
}
switch ((((UIntN)src8)PRE_SWITCH_ADJUST) & (TYPE_WIDTH - 1)) {
case 0: COPY_NO_SHIFT(); break;
case 1: COPY_SHIFT(1); break;
case 2: COPY_SHIFT(2); break;
case 3: COPY_SHIFT(3); break;
#if TYPE_WIDTH > 4
case 4: COPY_SHIFT(4); break;
case 5: COPY_SHIFT(5); break;
case 6: COPY_SHIFT(6); break;
case 7: COPY_SHIFT(7); break;
#endif
}
}