1/* strcspn (str, ss) -- Return the length of the initial segment of STR
2			which contains no characters from SS.
3   For AMD x86-64.
4   Copyright (C) 1994-2021 Free Software Foundation, Inc.
5   This file is part of the GNU C Library.
6
7   The GNU C Library is free software; you can redistribute it and/or
8   modify it under the terms of the GNU Lesser General Public
9   License as published by the Free Software Foundation; either
10   version 2.1 of the License, or (at your option) any later version.
11
12   The GNU C Library is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15   Lesser General Public License for more details.
16
17   You should have received a copy of the GNU Lesser General Public
18   License along with the GNU C Library; if not, see
19   <https://www.gnu.org/licenses/>.  */
20
21#include <sysdep.h>
22#include "asm-syntax.h"
23
24	.text
25ENTRY (strcspn)
26
27	movq %rdi, %rdx		/* Save SRC.  */
28
29	/* First we create a table with flags for all possible characters.
30	   For the ASCII (7bit/8bit) or ISO-8859-X character sets which are
31	   supported by the C string functions we have 256 characters.
32	   Before inserting marks for the stop characters we clear the whole
33	   table.  */
34	movq %rdi, %r8			/* Save value.  */
35	subq $256, %rsp			/* Make space for 256 bytes.  */
36	cfi_adjust_cfa_offset(256)
37	movl $32,  %ecx			/* 32*8 bytes = 256 bytes.  */
38	movq %rsp, %rdi
39	xorl %eax, %eax			/* We store 0s.  */
40	cld
41	rep
42	stosq
43
44	movq %rsi, %rax			/* Setup skipset.  */
45
46/* For understanding the following code remember that %rcx == 0 now.
47   Although all the following instruction only modify %cl we always
48   have a correct zero-extended 64-bit value in %rcx.  */
49
50	.p2align 4
51L(2):	movb (%rax), %cl	/* get byte from skipset */
52	testb %cl, %cl		/* is NUL char? */
53	jz L(1)			/* yes => start compare loop */
54	movb %cl, (%rsp,%rcx)	/* set corresponding byte in skipset table */
55
56	movb 1(%rax), %cl	/* get byte from skipset */
57	testb $0xff, %cl	/* is NUL char? */
58	jz L(1)			/* yes => start compare loop */
59	movb %cl, (%rsp,%rcx)	/* set corresponding byte in skipset table */
60
61	movb 2(%rax), %cl	/* get byte from skipset */
62	testb $0xff, %cl	/* is NUL char? */
63	jz L(1)			/* yes => start compare loop */
64	movb %cl, (%rsp,%rcx)	/* set corresponding byte in skipset table */
65
66	movb 3(%rax), %cl	/* get byte from skipset */
67	addq $4, %rax		/* increment skipset pointer */
68	movb %cl, (%rsp,%rcx)	/* set corresponding byte in skipset table */
69	testb $0xff, %cl	/* is NUL char? */
70	jnz L(2)		/* no => process next dword from skipset */
71
72L(1):	leaq -4(%rdx), %rax	/* prepare loop */
73
74	/* We use a neat trick for the following loop.  Normally we would
75	   have to test for two termination conditions
76	   1. a character in the skipset was found
77	   and
78	   2. the end of the string was found
79	   But as a sign that the character is in the skipset we store its
80	   value in the table.  But the value of NUL is NUL so the loop
81	   terminates for NUL in every case.  */
82
83	.p2align 4
84L(3):	addq $4, %rax		/* adjust pointer for full loop round */
85
86	movb (%rax), %cl	/* get byte from string */
87	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
88	je L(4)			/* yes => return */
89
90	movb 1(%rax), %cl	/* get byte from string */
91	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
92	je L(5)			/* yes => return */
93
94	movb 2(%rax), %cl	/* get byte from string */
95	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
96	jz L(6)			/* yes => return */
97
98	movb 3(%rax), %cl	/* get byte from string */
99	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
100	jne L(3)		/* no => start loop again */
101
102	incq %rax		/* adjust pointer */
103L(6):	incq %rax
104L(5):	incq %rax
105
106L(4):	addq $256, %rsp		/* remove skipset */
107	cfi_adjust_cfa_offset(-256)
108#ifdef USE_AS_STRPBRK
109	xorl %edx,%edx
110	orb %cl, %cl		/* was last character NUL? */
111	cmovzq %rdx, %rax	/* Yes:	return NULL */
112#else
113	subq %rdx, %rax		/* we have to return the number of valid
114				   characters, so compute distance to first
115				   non-valid character */
116#endif
117	ret
118END (strcspn)
119libc_hidden_builtin_def (strcspn)
120