349 lines
14 KiB
C
349 lines
14 KiB
C
/****************************************************************************
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* File: libc/string/lib_vikmemcpy.c
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*
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* This is version of the optimized memcpy by Daniel Vik, adapted to the
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* NuttX environment.
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*
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* Copyright (C) 1999-2010 Daniel Vik
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*
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* Adaptations include:
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* - File name change
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* - Use of types defined in stdint.h
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* - Integration with the NuttX configuration system
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* - Other cosmetic changes for consistency with NuttX coding standards
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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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* 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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* CONFIG_ENDIAN_BIG
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* Uses processor with big endian addressing. Default is little endian.
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*
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* CONFIG_MEMCPY_PRE_INC_PTRS
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* Use pre increment of pointers. Default is post increment of pointers.
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*
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* CONFIG_MEMCPY_INDEXED_COPY
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* Copying data using array indexing. Using this option, disables the
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* CONFIG_MEMCPY_PRE_INC_PTRS option.
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*
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* CONFIG_MEMCPY_64BIT - Compiles memcpy for 64 bit architectures
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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 CONFIG_MEMCPY_INDEXED_COPY
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/********************************************************************
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* Included Files
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*******************************************************************/
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#include <nuttx/config.h>
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#include <nuttx/compiler.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <string.h>
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/********************************************************************
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* Pre-processor Definitions
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*******************************************************************/
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/* Can't support CONFIG_MEMCPY_64BIT if the platform does not have 64-bit
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* integer types.
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*/
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#ifndef CONFIG_HAVE_LONG_LONG
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# undef CONFIG_MEMCPY_64BIT
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#endif
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/* Remove definitions when CONFIG_MEMCPY_INDEXED_COPY is defined */
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#if defined (CONFIG_MEMCPY_INDEXED_COPY)
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# if defined (CONFIG_MEMCPY_PRE_INC_PTRS)
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# undef CONFIG_MEMCPY_PRE_INC_PTRS
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# endif /* CONFIG_MEMCPY_PRE_INC_PTRS */
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#endif /* CONFIG_MEMCPY_INDEXED_COPY */
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/* Definitions for pre and post increment of pointers */
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#if defined (CONFIG_MEMCPY_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_t*)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 /* CONFIG_MEMCPY_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_t*)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 /* CONFIG_MEMCPY_PRE_INC_PTRS */
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/* Definitions for endian-ness */
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#ifdef CONFIG_ENDIAN_BIG
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# define SHL <<
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# define SHR >>
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#else /* CONFIG_ENDIAN_BIG */
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# define SHL >>
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# define SHR <<
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#endif /* CONFIG_ENDIAN_BIG */
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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 (CONFIG_MEMCPY_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 /* CONFIG_MEMCPY_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 /* CONFIG_MEMCPY_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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{ \
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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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{ \
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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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{ \
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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) & \
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~(TYPE_WIDTH - 1)); \
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UIntN* srcN = (UIntN*)((((UIntN)src8) PRE_LOOP_ADJUST) & \
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~(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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{ \
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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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{ \
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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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* Type Definitions
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*******************************************************************/
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#ifdef CONFIG_MEMCPY_64BIT
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typedef uint64_t UIntN;
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# define TYPE_WIDTH 8L
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#else
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typedef uint32_t UIntN;
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# define TYPE_WIDTH 4L
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#endif
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/********************************************************************
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* Public Functions
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*******************************************************************/
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/********************************************************************
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* Name: memcpy
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*
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* Description:
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* Copies count bytes from src to dest. No overlap check is performed.
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*
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* Input Parameters:
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* 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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* Returned Value:
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* A pointer to destination buffer
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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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uint8_t *dst8 = (uint8_t*)dest;
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uint8_t *src8 = (uint8_t*)src;
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if (count < 8)
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{
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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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{
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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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{
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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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return dest;
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}
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