memcpy

sky_feiyang 2014-07-08

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void *Memcpy(void *dst, const void *src, size_t size)

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{

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    char *psrc;

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    char *pdst;

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    if(NULL == dst || NULL == src)

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    {

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        return NULL;

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    }

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    if((src < dst) && (char *)src + size > (char *)dst) // 重叠的话自后向前拷贝

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    {

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        psrc = (char *)src + size - 1;

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        pdst = (char *)dst + size - 1;

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        while(size--)

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        {

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            *pdst-- = *psrc--;

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        }

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    }

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    else

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    {

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        psrc = (char *)src;

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        pdst = (char *)dst;

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        while(size--)

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        {

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            *pdst++ = *psrc++;

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        }

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    }

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    return dst;