File: strtok.S

package info (click to toggle)
glibc 2.19-18+deb8u7
  • links: PTS, VCS
  • area: main
  • in suites: jessie-backports
  • size: 204,748 kB
  • sloc: ansic: 970,427; asm: 241,207; sh: 10,069; makefile: 8,476; cpp: 3,595; perl: 2,077; pascal: 1,839; awk: 1,704; yacc: 317; sed: 73
file content (208 lines) | stat: -rw-r--r-- 6,120 bytes parent folder | download | duplicates (10)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
/* strtok (str, delim) -- Return next DELIM separated token from STR.
   For AMD x86-64.
   Copyright (C) 1998-2014 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Based on i686 version contributed by Ulrich Drepper
   <drepper@cygnus.com>, 1998.

   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
   <http://www.gnu.org/licenses/>.  */

#include <sysdep.h>
#include "asm-syntax.h"

/* This file can be used for the strtok and strtok_r functions:

   strtok:
	INPUT PARAMETER:
	str		%rdi
	delim		%rsi

   strtok_r:
	INPUT PARAMETER:
	str		%rdi
	delim		%rsi
	save_ptr	%rdx

   We do a common implementation here.  */

#ifdef USE_AS_STRTOK_R
# define SAVE_PTR (%r9)
#else
	.bss
	.local save_ptr
	.type save_ptr, @object
	.size save_ptr, LP_SIZE
save_ptr:
	.space LP_SIZE

# ifdef PIC
#  define SAVE_PTR save_ptr(%rip)
# else
#  define SAVE_PTR save_ptr
# endif

# define FUNCTION strtok
#endif

	.text
ENTRY (FUNCTION)
	/* First we create a table with flags for all possible characters.
	   For the ASCII (7bit/8bit) or ISO-8859-X character sets which are
	   supported by the C string functions we have 256 characters.
	   Before inserting marks for the stop characters we clear the whole
	   table.  */
	movq %rdi, %r8			/* Save value.  */
	subq $256, %rsp			/* Make space for 256 bytes.  */
	cfi_adjust_cfa_offset(256)
	movl $32,  %ecx			/* 32*8 bytes = 256 bytes.  */
	movq %rsp, %rdi
	xorl %eax, %eax			/* We store 0s.  */
	cld
	rep
	stosq

	/* Note: %rcx = 0 !!! */

#ifdef USE_AS_STRTOK_R
	/* The value is stored in the third argument.  */
	mov %RDX_LP, %R9_LP	/* Save value - see def. of SAVE_PTR.  */
	mov (%rdx), %RAX_LP
#else
	/* The value is in the local variable defined above.  But
	   we have to take care for PIC code.  */
	mov SAVE_PTR, %RAX_LP
#endif
	movq %r8, %rdx		/* Get start of string.  */

	/* If the pointer is NULL we have to use the stored value of
	   the last run.  */
	cmpq $0, %rdx
	cmove %rax, %rdx
	testq %rdx, %rdx
	jz L(returnNULL)
	movq %rsi, %rax		/* Get start of delimiter set.  */

/* For understanding the following code remember that %rcx == 0 now.
   Although all the following instruction only modify %cl we always
   have a correct zero-extended 64-bit value in %rcx.  */

L(2):	movb (%rax), %cl	/* get byte from stopset */
	testb %cl, %cl		/* is NUL char? */
	jz L(1)			/* yes => start compare loop */
	movb %cl, (%rsp,%rcx)	/* set corresponding byte in stopset table */

	movb 1(%rax), %cl	/* get byte from stopset */
	testb $0xff, %cl	/* is NUL char? */
	jz L(1)			/* yes => start compare loop */
	movb %cl, (%rsp,%rcx)	/* set corresponding byte in stopset table */

	movb 2(%rax), %cl	/* get byte from stopset */
	testb $0xff, %cl	/* is NUL char? */
	jz L(1)			/* yes => start compare loop */
	movb %cl, (%rsp,%rcx)	/* set corresponding byte in stopset table */

	movb 3(%rax), %cl	/* get byte from stopset */
	addq $4, %rax		/* increment stopset pointer */
	movb %cl, (%rsp,%rcx)	/* set corresponding byte in stopset table */
	testb $0xff, %cl	/* is NUL char? */
	jnz L(2)		/* no => process next dword from stopset */

L(1):

	leaq -4(%rdx), %rax	/* prepare loop */

	/* We use a neat trick for the following loop.  Normally we would
	   have to test for two termination conditions
	   1. a character in the stopset was found
	   and
	   2. the end of the string was found
	   As a sign that the character is in the stopset we store its
	   value in the table.  The value of NUL is NUL so the loop
	   terminates for NUL in every case.  */

L(3):	addq $4, %rax		/* adjust pointer for full loop round */

	movb (%rax), %cl	/* get byte from string */
	testb %cl, (%rsp,%rcx)	/* is it contained in stopset? */
	jz L(4)			/* no => start of token */

	movb 1(%rax), %cl	/* get byte from string */
	testb %cl, (%rsp,%rcx)	/* is it contained in stopset? */
	jz L(5)			/* no => start of token */

	movb 2(%rax), %cl	/* get byte from string */
	testb %cl, (%rsp,%rcx)	/* is it contained in stopset? */
	jz L(6)			/* no => start of token */

	movb 3(%rax), %cl	/* get byte from string */
	testb %cl, (%rsp,%rcx)	/* is it contained in stopset? */
	jnz L(3)		/* yes => start of loop */

	incq %rax		/* adjust pointer */
L(6):	incq %rax
L(5):	incq %rax

	/* Now we have to terminate the string.  */

L(4):	leaq -4(%rax), %rdx	/* We use %rDX for the next run.  */

L(7):	addq $4, %rdx		/* adjust pointer for full loop round */

	movb (%rdx), %cl	/* get byte from string */
	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
	je L(8)			/* yes => return */

	movb 1(%rdx), %cl	/* get byte from string */
	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
	je L(9)			/* yes => return */

	movb 2(%rdx), %cl	/* get byte from string */
	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
	je L(10)		/* yes => return */

	movb 3(%rdx), %cl	/* get byte from string */
	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
	jne L(7)		/* no => start loop again */

	incq %rdx		/* adjust pointer */
L(10):	incq %rdx
L(9):	incq %rdx

L(8):	cmpq %rax, %rdx
	je L(returnNULL)	/* There was no token anymore.  */

	movb $0, (%rdx)		/* Terminate string.  */

	/* Are we at end of string?  */
	cmpb $0, %cl
	leaq 1(%rdx), %rcx
	cmovne %rcx, %rdx

	/* Store the pointer to the next character.  */
	mov %RDX_LP, SAVE_PTR

L(epilogue):
	/* Remove the stopset table.  */
	addq $256, %rsp
	cfi_adjust_cfa_offset(-256)
	retq

L(returnNULL):
	xorl %eax, %eax
	/* Store the pointer to the next character.  */
	mov %RDX_LP, SAVE_PTR
	jmp L(epilogue)

END (FUNCTION)