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
|
/*
Copyright 2022 Gabriel Jensen.
This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/
#include <zap/priv.h>
.globl zap_utf8enc
zap_utf8enc:
/*
zap_chr20 const * in
zap_chr8 * out
*/
#if defined(__amd64__)
# rdi: Current input codepoint.
# rsi: Current output octet.
# rax: Current codepoint.
# rdx: Temporary.
# Iterate over the input:
.loop:
movl (%rdi),%eax
cmpl $0xFFFF,%eax
jg .oct4
cmpl $0x7FF,%eax
jg .oct3
cmpl $0x7F,%eax
jg .oct2 # Otherwise, only one octet is needed.
# One octet:
.oct1:
# Octet #0:
movb %al,(%rsi) # No conversion needed:
incq %rsi
# Test if we have reached the null-terminator:
testb %al,%al
jz .done
jmp .cnt
# Two octets:
.oct2:
/* Octet #0: */
movl %eax,%edx
shrl $0x6,%edx
orb $0xC0,%dl
movb %dl,(%rsi)
incq %rsi
# Octet #1:
movl %eax,%edx
andb $0x3F,%dl
orb $0x80,%dl
movb %dl,(%rsi)
incq %rsi
jmp .cnt
# Three octets:
.oct3:
# Octet #0:
movl %eax,%edx
shrl $0xC,%edx
orb $0xE0,%dl
movb %dl,(%rsi)
incq %rsi
# Octet #1:
movl %eax,%edx
shrl $0x6,%edx
andb $0x3F,%dl
orb $0x80,%dl
movb %dl,(%rsi)
incq %rsi
# Octet #2:
movl %eax,%edx
andb $0x3F,%dl
orb $0x80,%dl
movb %dl,(%rsi)
incq %rsi
jmp .cnt
# Four octets:/
.oct4:
# Octet #0:
movl %eax,%edx
shrl $0x12,%edx
orb $0xF0,%dl
movb %dl,(%rsi)
incq %rsi
# Octet #1:
movl %eax,%edx
shrl $0xC,%edx
andb $0x3F,%dl
orb $0x80,%dl
movb %dl,(%rsi)
incq %rsi
# Octet #2:
movl %eax,%edx
shrl $0x6,%edx
andb $0x3F,%dl
orb $0x80,%dl
movb %dl,(%rsi)
incq %rsi
# Octet #3:
movl %eax,%edx
andb $0x3F,%dl
orb $0x80,%dl
movb %dl,(%rsi)
incq %rsi
# Continue to the next codepoint:
.cnt:
addq $0x4,%rdi
jmp .loop
# Done:
.done:
ret
#endif
|
