memcpy.c

Newlib 嵌入式 C库 标准实现代码

#if defined __thumb__

#include "../../string/memcpy.c"

#else

#include <string.h>
#include "xscale.h"

void *
memcpy (void *dst0, const void *src0, size_t len)
{
  int dummy;
  asm volatile (
#ifndef __OPTIMIZE_SIZE__
       "cmp	%2, #0x3\n\
	bls	3f\n\
	and	lr, %1, #0x3\n\
	and	r3, %0, #0x3\n\
	cmp	lr, r3\n\
	bne	3f\n\
	cmp	lr, #0x0\n\
	beq	2f\n\
	b	1f\n\
0:\n\
	ldrb	r3, [%1], #1\n\
"
	PRELOADSTR ("%1")
"\n\
	tst	%1, #0x3\n\
	strb	r3, [%0], #1\n\
	beq	3f\n\
1:\n\
	sub	%2, %2, #1\n\
	cmn	%2, #1\n\
	bne	0b\n\
2:\n\
	cmp	%2, #0xf\n\
	bls	1f\n\
0:\n\
	ldmia	%1!, { r3, r4, r5, lr }\n\
"
	PRELOADSTR ("%1")
"\n\
\n\
	sub	%2, %2, #16\n\
	cmp	%2, #0xf\n\
	stmia	%0!, { r3, r4, r5, lr }\n\
	bhi	0b\n\
1:\n\
	cmp	%2, #0x7\n\
	bls	1f\n\
0:\n\
	ldmia	%1!, { r3, r4 }\n\
"
	PRELOADSTR ("%1")
"\n\
\n\
	sub	%2, %2, #8\n\
	cmp	%2, #0x7\n\
	stmia	%0!, { r3, r4 }\n\
	bhi	0b\n\
1:\n\
	cmp	%2, #0x3\n\
	bls	3f\n\
0:\n\
	sub	%2, %2, #4\n\
	ldr	r3, [%1], #4\n\
"
	PRELOADSTR ("%1")
"\n\
\n\
	cmp	%2, #0x3\n\
	str	r3, [%0], #4\n\
	bhi	0b\n\
"
#endif /* !__OPTIMIZE_SIZE__ */
"\n\
3:\n\
"
	PRELOADSTR ("%1")
"\n\
	sub	%2, %2, #1\n\
	cmn	%2, #1\n\
	beq	1f\n\
0:\n\
	sub	%2, %2, #1\n\
	ldrb	r3, [%1], #1\n\
"
	PRELOADSTR ("%1")
"\n\
	cmn	%2, #1\n\
	strb	r3, [%0], #1\n\
	bne	0b\n\
1:"
       : "=&r" (dummy), "=&r" (src0), "=&r" (len)
       : "0" (dst0), "1" (src0), "2" (len)
       : "memory", "lr", "r3", "r4", "r5", "cc");
  return dst0;
}
#endif