alpha/lib/ev6-stxcpy.S

1 /* SPDX-License-Identifier: GPL-2.0 */
3  * arch/alpha/lib/ev6-stxcpy.S
4  * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
6  * Copy a null-terminated string from SRC to DST.
21  * Furthermore, v0, a3-a5, t11, and t12 are untouched.
26  *	ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
28  *	E	- either cluster
29  *	U	- upper subcluster; U0 - subcluster U0; U1 - subcluster U1
30  *	L	- lower subcluster; L0 - subcluster L0; L1 - subcluster L1
42    doesn't like putting the entry point for a procedure somewhere in the
53 	/* On entry to this basic block:
58 	lda	t2, -1		# E : build a mask against false zero
68 	/* On entry to this basic block:
79 	ldq_u	t1, 0(a1)	# L : Latency=3
85 	   On entry to this basic block we have:
98 	ldq_u	t0, 0(a0)	# L : Latency=3
109 	ret	(t9)		# L0 : Latency=3
122 	/* Are source and destination co-aligned?  */
128 	/* We are co-aligned; take care of a partial first word.  */
135 	br	stxcpy_aligned	# L0 : Latency=3
140 /* The source and destination are not co-aligned.  Align the destination
150 	   On entry to this basic block:
153 	   t6 == bytemask that is -1 in dest word bytes */
167 	lda	t6, -1		# E : for masking just below
180 	extql	t2, a1, t0	# U : position ho-bits of lo word
181 	ldq_u	t2, 8(a1)	# U : read next high-order source word
195 	   On entry to this basic block:
196 	   t0 == the shifted high-order bits from the previous source word
209 	ldq_u	t2, 0(a1)	# L : Latency=3 load high word for next time
210 	stq_u	t1, -8(a0)	# L : save the current word (stall)
223 	   On entry to this basic block:
224 	   t0 == the shifted high-order bits from the previous source word
233 	stq_u	t1, 0(a0)	# L : the null was in the high-order bits
239 	   On entry to this basic block:
259 	ret	(t9)		# L0 : Latency=3
263 	/* Unaligned copy entry point.  */
277 	lda	t6, -1		# E :
289 	lda	t2, -1		# E : mask out leading garbage in source