summaryrefslogtreecommitdiffstats
path: root/src/VBox/Runtime/common/string/strncpy.asm
blob: 20a028dc312f98affa7476eb94df5ea45eca2e33 (plain)
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
; $Id: strncpy.asm $
;; @file
; IPRT - No-CRT strncpy - AMD64 & X86.
;

;
; Copyright (C) 2006-2023 Oracle and/or its affiliates.
;
; This file is part of VirtualBox base platform packages, as
; available from https://www.virtualbox.org.
;
; This program is free software; you can redistribute it and/or
; modify it under the terms of the GNU General Public License
; as published by the Free Software Foundation, in version 3 of the
; License.
;
; This program 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
; General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program; if not, see <https://www.gnu.org/licenses>.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
; in the VirtualBox distribution, in which case the provisions of the
; CDDL are applicable instead of those of the GPL.
;
; You may elect to license modified versions of this file under the
; terms and conditions of either the GPL or the CDDL or both.
;
; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
;

%include "iprt/asmdefs.mac"

BEGINCODE

;;
; @param    pszDst   gcc: rdi  msc: rcx  x86:[esp+4]   wcall: eax
; @param    pszSrc   gcc: rsi  msc: rdx  x86:[esp+8]   wcall: edx
; @param    cbMax    gcc: rdx  msc: r8   x86:[esp+12]  wcall: ebx
RT_NOCRT_BEGINPROC strncpy
        ; input
%ifdef RT_ARCH_AMD64
 %ifdef ASM_CALL64_MSC
  %define pszDst rcx
  %define pszSrc rdx
  %define cbMax  r8
 %else
  %define pszDst rdi
  %define pszSrc rsi
  %define cbMax  rdx
 %endif
        mov     r9, pszDst
%else
 %ifdef ASM_CALL32_WATCOM
  mov   ecx, eax
  %define pszDst ecx
  %define pszSrc edx
  %define cbMax  ebx
 %else
        mov     ecx, [esp + 4]
        mov     edx, [esp + 8]
        push    ebx
        mov     ebx, [esp + 12 + 4]
  %define pszDst ecx
  %define pszSrc edx
  %define cbMax  ebx
 %endif
        push    pszDst
%endif

        ;
        ; The rolled out loop.
        ;
.next:
        cmp     cbMax, 4
        jb      .simple_intro

        mov     al, [pszSrc]
        mov     [pszDst], al
        test    al, al
        jz      .done

        mov     al, [pszSrc + 1]
        mov     [pszDst + 1], al
        test    al, al
        jz      .done

        mov     al, [pszSrc + 2]
        mov     [pszDst + 2], al
        test    al, al
        jz      .done

        mov     al, [pszSrc + 3]
        mov     [pszDst + 3], al
        test    al, al
        jz      .done

        add     pszDst, 4
        add     pszSrc, 4
        sub     cbMax,  4
        jmp     .next

        ;
        ; Char by char.
        ;
.simple_intro:
        test    cbMax, cbMax
        jz      .done

.simple_next:
        mov     al, [pszSrc]
        mov     [pszDst], al
        test    al, al
        jz      .done

        dec     cbMax
        jz      .done

        inc     pszSrc
        inc     pszDst
        jmp     .simple_next

.done:
%ifdef RT_ARCH_AMD64
        mov     rax, r9
%else
 %ifndef ASM_CALL32_WATCOM
        pop     ebx
 %endif
        pop     eax
%endif
        ret
ENDPROC RT_NOCRT(strncpy)