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/*
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 * Copyright (c) 2005 Sergey Bondari
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup ia32   
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 * @{
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 */
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/** @file
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 */
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#ifndef KERN_ia32_MEMSTR_H_
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#define KERN_ia32_MEMSTR_H_
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/** Copy memory
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 *
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 * Copy a given number of bytes (3rd argument)
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 * from the memory location defined by 2nd argument
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 * to the memory location defined by 1st argument.
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 * The memory areas cannot overlap.
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 *
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 * @param dst Destination
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 * @param src Source
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 * @param cnt Number of bytes
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 * @return Destination
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 */
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static inline void * memcpy(void * dst, const void * src, size_t cnt)
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{
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        unative_t d0, d1, d2;
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        asm volatile(
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                /* copy all full dwords */
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                "rep movsl\n\t"
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                /* load count again */
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                "movl %4, %%ecx\n\t"
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                /* ecx = ecx mod 4 */
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                "andl $3, %%ecx\n\t"
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                /* are there last <=3 bytes? */
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                "jz 1f\n\t"
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                /* copy last <=3 bytes */
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                "rep movsb\n\t"
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                /* exit from asm block */
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                "1:\n"
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                : "=&c" (d0), "=&D" (d1), "=&S" (d2)
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                : "0" ((unative_t) (cnt / 4)), "g" ((unative_t) cnt), "1" ((unative_t) dst), "2" ((unative_t) src)
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                : "memory");
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        return dst;
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}
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/** Compare memory regions for equality
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 *
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 * Compare a given number of bytes (3rd argument)
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 * at memory locations defined by 1st and 2nd argument
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 * for equality. If bytes are equal function returns 0.
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 *
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 * @param src Region 1
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 * @param dst Region 2
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 * @param cnt Number of bytes
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 * @return Zero if bytes are equal, non-zero otherwise
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 */
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static inline int memcmp(const void * src, const void * dst, size_t cnt)
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{
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    uint32_t d0, d1, d2;
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    int ret;
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    asm (
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        "repe cmpsb\n\t"
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        "je 1f\n\t"
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        "movl %3, %0\n\t"
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        "addl $1, %0\n\t"
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        "1:\n"
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        : "=a" (ret), "=%S" (d0), "=&D" (d1), "=&c" (d2)
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        : "0" (0), "1" ((unative_t) src), "2" ((unative_t) dst), "3" ((unative_t) cnt)
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    );
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    return ret;
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}
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/** Fill memory with words
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 * Fill a given number of words (2nd argument)
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 * at memory defined by 1st argument with the
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 * word value defined by 3rd argument.
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 *
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 * @param dst Destination
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 * @param cnt Number of words
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 * @param x Value to fill
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 */
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static inline void memsetw(uintptr_t dst, size_t cnt, uint16_t x)
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{
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    uint32_t d0, d1;
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    asm volatile (
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        "rep stosw\n\t"
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        : "=&D" (d0), "=&c" (d1), "=a" (x)
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        : "0" (dst), "1" (cnt), "2" (x)
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        : "memory"
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    );
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}
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/** Fill memory with bytes
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 * Fill a given number of bytes (2nd argument)
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 * at memory defined by 1st argument with the
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 * word value defined by 3rd argument.
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 *
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 * @param dst Destination
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 * @param cnt Number of bytes
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 * @param x Value to fill
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 */
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static inline void memsetb(uintptr_t dst, size_t cnt, uint8_t x)
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{
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    uint32_t d0, d1;
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    asm volatile (
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        "rep stosb\n\t"
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        : "=&D" (d0), "=&c" (d1), "=a" (x)
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        : "0" (dst), "1" (cnt), "2" (x)
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        : "memory"
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    );
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}
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#endif
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/** @}
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 */