~linaro-toolchain-dev/cortex-strings/trunk

#include <string.h>

#include "xscale.h"

void *

memset (void *dst, int c, size_t len)

{

  int dummy;

  asm volatile ("tst	%0, #0x3"

#ifndef __OPTIMIZE_SIZE__

"\n\

	beq	1f\n\

	b	2f\n\

0:\n\

	strb	%1, [%0], #1\n\

	tst	%0, #0x3\n\

	beq	1f\n\

2:\n\

	movs	r3, %2\n\

	sub	%2, %2, #1\n\

	bne	0b\n\

# At this point we know that %2 == len == -1 (since the SUB has already taken\n\

# place).  If we fall through to the 1: label (as the code used to do), the\n\

# CMP will detect this negative value and branch to the 2: label.  This will\n\

# test %2 again, but this time against 0.  The test will fail and the loop\n\

# at 2: will go on for (almost) ever.  Hence the explicit branch to the end\n\

# of the hand written assembly code.\n\

	b       4f\n\

1:\n\

	cmp	%2, #0x3\n\

	bls	2f\n\

	and	%1, %1, #0xff\n\

	orr	lr, %1, %1, asl #8\n\

	cmp	%2, #0xf\n\

	orr	lr, lr, lr, asl #16\n\

	bls	1f\n\

	mov	r3, lr\n\

	mov	r4, lr\n\

	mov	r5, lr\n\

0:\n\

	sub	%2, %2, #16\n\

	stmia	%0!, { r3, r4, r5, lr }\n\

	cmp	%2, #0xf\n\

	bhi	0b\n\

1:\n\

	cmp	%2, #0x7\n\

	bls	1f\n\

	mov	r3, lr\n\

0:\n\

	sub	%2, %2, #8\n\

	stmia	%0!, { r3, lr }\n\

	cmp	%2, #0x7\n\

	bhi	0b\n\

1:\n\

	cmp	%2, #0x3\n\

	bls	2f\n\

0:\n\

	sub	%2, %2, #4\n\

	str	lr, [%0], #4\n\

	cmp	%2, #0x3\n\

	bhi	0b\n\

"

#endif /* !__OPTIMIZE_SIZE__ */

"\n\

2:\n\

	movs	r3, %2\n\

	sub	%2, %2, #1\n\

	beq	4f\n\

0:\n\

	movs	r3, %2\n\

	sub	%2, %2, #1\n\

	strb	%1, [%0], #1\n\

	bne	0b\n\

4:"

       : "=&r" (dummy), "=&r" (c), "=&r" (len)

       : "0" (dst), "1" (c), "2" (len)

       : "memory", "r3", "r4", "r5", "lr");

  return dst;

}