[thirdparty/glibc.git] / sysdeps / powerpc / powerpc32 / power7 / strchrnul.S

/* Optimized strchrnul implementation for PowerPC32/POWER7 using cmpb insn.
   Copyright (C) 2010-2019 Free Software Foundation, Inc.
   Contributed by Luis Machado <luisgpm@br.ibm.com>.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <sysdep.h>

/* int [r3] strchrnul (char *s [r3], int c [r4])  */
	.machine  power7
ENTRY (__strchrnul)
	CALL_MCOUNT
	dcbt	0,r3
	clrrwi	r8,r3,2	      /* Align the address to word boundary.  */

	/* Replicate byte to word.  */
	insrwi  r4,r4,8,16
	insrwi  r4,r4,16,0

	rlwinm	r6,r3,3,27,28 /* Calculate padding.  */
	lwz	r12,0(r8)     /* Load word from memory.  */
	li	r0,0	      /* Word with null chars to use
				 with cmpb.  */

	/* Now r4 has a word of c bytes and r0 has
	   a word of null bytes.  */

	cmpb	r10,r12,r0    /* Compare each byte against c byte.  */
	cmpb	r9,r12,r4     /* Compare each byte against null byte.  */

	/* Move the words left and right to discard the bits that are
	   not part of the string and bring them back as zeros.  */
#ifdef __LITTLE_ENDIAN__
	srw	r10,r10,r6
	srw	r9,r9,r6
	slw	r10,r10,r6
	slw	r9,r9,r6
#else
	slw	r10,r10,r6
	slw	r9,r9,r6
	srw	r10,r10,r6
	srw	r9,r9,r6
#endif
	or	r5,r9,r10     /* OR the results to speed things up.  */
	cmpwi	cr7,r5,0      /* If r5 == 0, no c or null bytes
				 have been found.  */
	bne	cr7,L(done)

	mtcrf   0x01,r8

	/* Are we now aligned to a doubleword boundary?  If so, skip to
	   the main loop.  Otherwise, go through the alignment code.  */

	bt	29,L(loop)

	/* Handle WORD2 of pair.  */
	lwzu	r12,4(r8)
	cmpb	r10,r12,r0
	cmpb	r9,r12,r4
	or	r5,r9,r10
	cmpwi	cr7,r5,0
	bne	cr7,L(done)
	b	L(loop)	      /* We branch here (rather than falling through)
				 to skip the nops due to heavy alignment
				 of the loop below.  */

	.p2align  5
L(loop):
	/* Load two words, compare and merge in a
	   single register for speed.  This is an attempt
	   to speed up the null-checking process for bigger strings.  */
	lwz	r12,4(r8)
	lwzu	r11,8(r8)
	cmpb	r10,r12,r0
	cmpb	r9,r12,r4
	cmpb	r6,r11,r0
	cmpb	r7,r11,r4
	or	r5,r9,r10
	or	r10,r6,r7
	or	r11,r5,r10
	cmpwi	cr7,r11,0
	beq	cr7,L(loop)

	/* OK, one (or both) of the words contains a c/null byte.  Check
	   the first word and decrement the address in case the first
	   word really contains a c/null byte.  */

	cmpwi	cr6,r5,0
	addi	r8,r8,-4
	bne	cr6,L(done)

	/* The c/null byte must be in the second word.  Adjust the address
	   again and move the result of cmpb to r5 so we can calculate the
	   pointer.  */
	mr	r5,r10
	addi	r8,r8,4

	/* r5 has the output of the cmpb instruction, that is, it contains
	   0xff in the same position as the c/null byte in the original
	   word from the string.  Use that to calculate the pointer.  */
L(done):
#ifdef __LITTLE_ENDIAN__
	addi    r0,r5,-1
	andc    r0,r0,r5
	popcntw	r0,r0
#else
	cntlzw	r0,r5	      /* Count leading zeros before the match.  */
#endif
	srwi	r0,r0,3	      /* Convert leading zeros to bytes.  */
	add	r3,r8,r0      /* Return address of matching c/null byte.  */
	blr
END (__strchrnul)
weak_alias (__strchrnul,strchrnul)
libc_hidden_builtin_def (__strchrnul)
Commit	Line	Data
fe2f79db	1	/* Optimized strchrnul implementation for PowerPC32/POWER7 using cmpb insn.
04277e02	2	Copyright (C) 2010-2019 Free Software Foundation, Inc.
fe2f79db LM	3	Contributed by Luis Machado <luisgpm@br.ibm.com>.
	4	This file is part of the GNU C Library.
	5
	6	The GNU C Library is free software; you can redistribute it and/or
	7	modify it under the terms of the GNU Lesser General Public
	8	License as published by the Free Software Foundation; either
	9	version 2.1 of the License, or (at your option) any later version.
	10
	11	The GNU C Library is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	Lesser General Public License for more details.
	15
	16	You should have received a copy of the GNU Lesser General Public
59ba27a6	17	License along with the GNU C Library; if not, see
5a82c748	18	<https://www.gnu.org/licenses/>. */
fe2f79db LM	19
fe2f79db LM	20	#include <sysdep.h>
fe2f79db LM	21
	22	/* int [r3] strchrnul (char s [r3], int c [r4]) /
	23	.machine power7
b5510883	24	ENTRY (__strchrnul)
fe2f79db LM	25	CALL_MCOUNT
	26	dcbt 0,r3
	27	clrrwi r8,r3,2 /* Align the address to word boundary. */
	28
	29	/* Replicate byte to word. */
d298c416 AZ	30	insrwi r4,r4,8,16
d298c416 AZ	31	insrwi r4,r4,16,0
fe2f79db LM	32
	33	rlwinm r6,r3,3,27,28 /* Calculate padding. */
	34	lwz r12,0(r8) /* Load word from memory. */
	35	li r0,0 /* Word with null chars to use
	36	with cmpb. */
	37
	38	/* Now r4 has a word of c bytes and r0 has
	39	a word of null bytes. */
	40
	41	cmpb r10,r12,r0 /* Compare each byte against c byte. */
	42	cmpb r9,r12,r4 /* Compare each byte against null byte. */
	43
	44	/* Move the words left and right to discard the bits that are
	45	not part of the string and bring them back as zeros. */
664318c3 AM	46	#ifdef __LITTLE_ENDIAN__
	47	srw r10,r10,r6
	48	srw r9,r9,r6
	49	slw r10,r10,r6
	50	slw r9,r9,r6
	51	#else
fe2f79db LM	52	slw r10,r10,r6
	53	slw r9,r9,r6
	54	srw r10,r10,r6
	55	srw r9,r9,r6
664318c3	56	#endif
fe2f79db LM	57	or r5,r9,r10 /* OR the results to speed things up. */
	58	cmpwi cr7,r5,0 /* If r5 == 0, no c or null bytes
	59	have been found. */
	60	bne cr7,L(done)
	61
	62	mtcrf 0x01,r8
	63
664318c3	64	/* Are we now aligned to a doubleword boundary? If so, skip to
fe2f79db LM	65	the main loop. Otherwise, go through the alignment code. */
	66
	67	bt 29,L(loop)
	68
	69	/* Handle WORD2 of pair. */
	70	lwzu r12,4(r8)
	71	cmpb r10,r12,r0
	72	cmpb r9,r12,r4
	73	or r5,r9,r10
	74	cmpwi cr7,r5,0
	75	bne cr7,L(done)
	76	b L(loop) /* We branch here (rather than falling through)
	77	to skip the nops due to heavy alignment
	78	of the loop below. */
	79
	80	.p2align 5
	81	L(loop):
	82	/* Load two words, compare and merge in a
	83	single register for speed. This is an attempt
	84	to speed up the null-checking process for bigger strings. */
	85	lwz r12,4(r8)
664318c3	86	lwzu r11,8(r8)
fe2f79db LM	87	cmpb r10,r12,r0
	88	cmpb r9,r12,r4
	89	cmpb r6,r11,r0
	90	cmpb r7,r11,r4
	91	or r5,r9,r10
	92	or r10,r6,r7
	93	or r11,r5,r10
	94	cmpwi cr7,r11,0
	95	beq cr7,L(loop)
	96
	97	/* OK, one (or both) of the words contains a c/null byte. Check
	98	the first word and decrement the address in case the first
	99	word really contains a c/null byte. */
	100
	101	cmpwi cr6,r5,0
	102	addi r8,r8,-4
	103	bne cr6,L(done)
	104
664318c3 AM	105	/* The c/null byte must be in the second word. Adjust the address
	106	again and move the result of cmpb to r5 so we can calculate the
	107	pointer. */
fe2f79db LM	108	mr r5,r10
	109	addi r8,r8,4
	110
	111	/* r5 has the output of the cmpb instruction, that is, it contains
	112	0xff in the same position as the c/null byte in the original
	113	word from the string. Use that to calculate the pointer. */
	114	L(done):
664318c3 AM	115	#ifdef __LITTLE_ENDIAN__
	116	addi r0,r5,-1
	117	andc r0,r0,r5
	118	popcntw r0,r0
	119	#else
fe2f79db	120	cntlzw r0,r5 /* Count leading zeros before the match. */
664318c3	121	#endif
fe2f79db LM	122	srwi r0,r0,3 /* Convert leading zeros to bytes. */
	123	add r3,r8,r0 /* Return address of matching c/null byte. */
	124	blr
b5510883	125	END (__strchrnul)
fe2f79db LM	126	weak_alias (__strchrnul,strchrnul)
fe2f79db LM	127	libc_hidden_builtin_def (__strchrnul)