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