arch/arc/lib/strcpy-700.S

/*
 * Copyright (C) 2004, 2007-2010, 2011-2014 Synopsys, Inc. All rights reserved.
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

/*
 * If dst and src are 4 byte aligned, copy 8 bytes at a time.
 * If the src is 4, but not 8 byte aligned, we first read 4 bytes to get
 * it 8 byte aligned.  Thus, we can do a little read-ahead, without
 * dereferencing a cache line that we should not touch.
 * Note that short and long instructions have been scheduled to avoid
 * branch stalls.
 * The beq_s to r3z could be made unaligned & long to avoid a stall
 * there, but it is not likely to be taken often, and it would also be likely
 * to cost an unaligned mispredict at the next call.
 */

.global strcpy
.align 4
strcpy:
	or	%r2, %r0, %r1
	bmsk_s	%r2, %r2, 1
	brne.d	%r2, 0, charloop
	mov_s	%r10, %r0
	ld_s	%r3, [%r1, 0]
	mov	%r8, 0x01010101
	bbit0.d	%r1, 2, loop_start
	ror	%r12, %r8
	sub	%r2, %r3, %r8
	bic_s	%r2, %r2, %r3
	tst_s	%r2,%r12
	bne	r3z
	mov_s	%r4,%r3
	.balign 4
loop:
	ld.a	%r3, [%r1, 4]
	st.ab	%r4, [%r10, 4]
loop_start:
	ld.a	%r4, [%r1, 4]
	sub	%r2, %r3, %r8
	bic_s	%r2, %r2, %r3
	tst_s	%r2, %r12
	bne_s	r3z
	st.ab	%r3, [%r10, 4]
	sub	%r2, %r4, %r8
	bic	%r2, %r2, %r4
	tst	%r2, %r12
	beq	loop
	mov_s	%r3, %r4
#ifdef __LITTLE_ENDIAN__
r3z:	bmsk.f	%r1, %r3, 7
	lsr_s	%r3, %r3, 8
#else /* __BIG_ENDIAN__ */
r3z:	lsr.f	%r1, %r3, 24
	asl_s	%r3, %r3, 8
#endif /* _ENDIAN__ */
	bne.d	r3z
	stb.ab	%r1, [%r10, 1]
	j_s	[%blink]

	.balign	4
charloop:
	ldb.ab	%r3, [%r1, 1]
	brne.d	%r3, 0, charloop
	stb.ab	%r3, [%r10, 1]
	j	[%blink]