memcpy.c

来自「国产CPU－龙芯（loongson)BIOS源代码」· C语言 代码 · 共 54 行

/* simple memory copy function */
#if 1
void memcpy(void *to, void *from, int size)
{
    int i = 0;
    for(i=0;i<size;i+=4)
    {
	*(unsigned char *)(to++) = *(unsigned char *)(from++);
	*(unsigned char *)(to++) = *(unsigned char *)(from++);
	*(unsigned char *)(to++) = *(unsigned char *)(from++);
	*(unsigned char *)(to++) = *(unsigned char *)(from++);

	/*
	*(unsigned short *)(to)=*(unsigned short *)(from);
	to+=2;
	from+=2;
	*(unsigned short *)(to)=*(unsigned short *)(from);
	to+=2;
	from+=2;
	*/

	/* why in simos the below code does not work properly
	 * Maybe the address not aligned 
	*(unsigned long *)(to) = *(unsigned long *)(from);
	to+=4;
	from+=4;
	*/
    }
    switch (size%4)
    {
	case 1:
	    *(unsigned char *)(to)=*(unsigned char *)(from);
	    break;
	case 2:
	    *(unsigned short *)(to)=*(unsigned short *)(from);
	    break;
	case 3:
	    *(unsigned char *)(to++)=*(unsigned char *)(from++);
	    *(unsigned short *)(to)=*(unsigned short *)(from);
	    break;
	case 0:
	default:
	    break;
    }
}
#else
void memcpy(void *to, void *from, int size)
{
    int i = 0;
    for (i=0;i<size;i++)
	*(unsigned char *)(to++) = *(unsigned char *)(from++);
}
#endif