reactos/sdk/lib/ucrt/string/i386/strcat.s
2025-01-22 18:56:08 +02:00

235 lines
6.5 KiB
ArmAsm

#include <asm.inc>
#if 0
page ,132
title strcat - concatenate (append) one string to another
;***
;strcat.asm - contains strcat() and strcpy() routines
;
; Copyright (c) Microsoft Corporation. All rights reserved.
;
;Purpose:
; STRCAT concatenates (appends) a copy of the source string to the
; end of the destination string, returning the destination string.
;
;*******************************************************************************
.xlist
include cruntime.inc
.list
page
;***
;char *strcat(dst, src) - concatenate (append) one string to another
;
;Purpose:
; Concatenates src onto the end of dest. Assumes enough
; space in dest.
;
; Algorithm:
; char * strcat (char * dst, char * src)
; {
; char * cp = dst;
;
; while( *cp )
; ++cp; /* Find end of dst */
; while( *cp++ = *src++ )
; ; /* Copy src to end of dst */
; return( dst );
; }
;
;Entry:
; char *dst - string to which "src" is to be appended
; const char *src - string to be appended to the end of "dst"
;
;Exit:
; The address of "dst" in EAX
;
;Uses:
; EAX, ECX
;
;Exceptions:
;
;*******************************************************************************
page
;***
;char *strcpy(dst, src) - copy one string over another
;
;Purpose:
; Copies the string src into the spot specified by
; dest; assumes enough room.
;
; Algorithm:
; char * strcpy (char * dst, char * src)
; {
; char * cp = dst;
;
; while( *cp++ = *src++ )
; ; /* Copy src over dst */
; return( dst );
; }
;
;Entry:
; char * dst - string over which "src" is to be copied
; const char * src - string to be copied over "dst"
;
;Exit:
; The address of "dst" in EAX
;
;Uses:
; EAX, ECX
;
;Exceptions:
;*******************************************************************************
#endif
.code
public _strcat
public _strcpy // make both functions available
.PROC _strcpy
// dst:ptr byte, \
// src:ptr byte
//OPTION PROLOGUE:NONE, EPILOGUE:NONE
push edi // preserve edi
mov edi,[esp+8] // edi points to dest string
jmp short copy_start
.ENDP // _strcpy
align 16
.PROC _strcat
// dst:ptr byte, \
// src:ptr byte
//OPTION PROLOGUE:NONE, EPILOGUE:NONE
FPO 0, 2, 0, 0, 0, 0
mov ecx,[esp+4] // ecx -> dest string
push edi // preserve edi
test ecx,3 // test if string is aligned on 32 bits
je short find_end_of_dest_string_loop
dest_misaligned: // simple byte loop until string is aligned
mov al,byte ptr [ecx]
add ecx,1
test al,al
je short start_byte_3
test ecx,3
jne short dest_misaligned
align 4
find_end_of_dest_string_loop:
mov eax,dword ptr [ecx] // read 4 bytes
mov edx,HEX(7efefeff)
add edx,eax
xor eax,-1
xor eax,edx
add ecx,4
test eax,HEX(81010100)
je short find_end_of_dest_string_loop
// found zero byte in the loop
mov eax,[ecx - 4]
test al,al // is it byte 0
je short start_byte_0
test ah,ah // is it byte 1
je short start_byte_1
test eax,HEX(00ff0000) // is it byte 2
je short start_byte_2
test eax,HEX(0ff000000) // is it byte 3
je short start_byte_3
jmp short find_end_of_dest_string_loop
// taken if bits 24-30 are clear and bit
// 31 is set
start_byte_3:
lea edi,[ecx - 1]
jmp short copy_start
start_byte_2:
lea edi,[ecx - 2]
jmp short copy_start
start_byte_1:
lea edi,[ecx - 3]
jmp short copy_start
start_byte_0:
lea edi,[ecx - 4]
// jmp short copy_start
// edi points to the end of dest string.
GLOBAL_LABEL copy_start
mov ecx,[esp+HEX(0c)] // ecx -> sorc string
test ecx,3 // test if string is aligned on 32 bits
je short main_loop_entrance
src_misaligned: // simple byte loop until string is aligned
mov dl,byte ptr [ecx]
add ecx,1
test dl,dl
je short byte_0
mov [edi],dl
add edi,1
test ecx,3
jne short src_misaligned
jmp short main_loop_entrance
main_loop: // edx contains first dword of sorc string
mov [edi],edx // store one more dword
add edi,4 // kick dest pointer
main_loop_entrance:
mov edx,HEX(7efefeff)
mov eax,dword ptr [ecx] // read 4 bytes
add edx,eax
xor eax,-1
xor eax,edx
mov edx,[ecx] // it's in cache now
add ecx,4 // kick dest pointer
test eax,HEX(81010100)
je short main_loop
// found zero byte in the loop
; main_loop_end:
test dl,dl // is it byte 0
je short byte_0
test dh,dh // is it byte 1
je short byte_1
test edx,HEX(00ff0000) // is it byte 2
je short byte_2
test edx,HEX(0ff000000) // is it byte 3
je short byte_3
jmp short main_loop // taken if bits 24-30 are clear and bit
// 31 is set
byte_3:
mov [edi],edx
mov eax,[esp+8] // return in eax pointer to dest string
pop edi
ret
byte_2:
mov [edi],dx
mov eax,[esp+8] // return in eax pointer to dest string
mov byte ptr [edi+2],0
pop edi
ret
byte_1:
mov [edi],dx
mov eax,[esp+8] // return in eax pointer to dest string
pop edi
ret
byte_0:
mov [edi],dl
mov eax,[esp+8] // return in eax pointer to dest string
pop edi
ret
.ENDP // _strcat
end