(* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1
*
* The implementation of function PosEx is subject to the
* Mozilla Public License Version 1.1 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Fastcode
*
* The Initial Developer of the Original Code is Fastcode
*
* Portions created by the Initial Developer are Copyright © 2002-2004
* the Initial Developer. All Rights Reserved.
*
* Contributor(s): Aleksandr Sharahov
*
* ***** END LICENSE BLOCK ***** *)
function PosEx(const SubStr, S: string; Offset: Integer = 1): Integer;
asm
test eax, eax
jz @Nil
test edx, edx
jz @Nil
dec ecx
jl @Nil

push esi
push ebx

mov esi, [edx-4] //Length(Str)
mov ebx, [eax-4] //Length(Substr)
sub esi, ecx //effective length of Str
add edx, ecx //addr of the first char at starting position
cmp esi, ebx
jl @Past //jump if EffectiveLength(Str)<Length(Substr)
test ebx, ebx
jle @Past //jump if Length(Substr)<=0

add esp, -12
add ebx, -1 //Length(Substr)-1
add esi, edx //addr of the terminator
add edx, ebx //addr of the last char at starting position
mov [esp+8], esi //save addr of the terminator
add eax, ebx //addr of the last char of Substr
sub ecx, edx //-@Str[Length(Substr)]
neg ebx //-(Length(Substr)-1)
mov [esp+4], ecx //save -@Str[Length(Substr)]
mov [esp], ebx //save -(Length(Substr)-1)
movzx ecx, byte ptr [eax] //the last char of Substr

@Loop:
cmp cl, [edx]
jz @Test0
@AfterTest0:
cmp cl, [edx+1]
jz @TestT
@AfterTestT:
add edx, 4
cmp edx, [esp+8]
jb @Continue
@EndLoop:
add edx, -2
cmp edx, [esp+8]
jb @Loop
@Exit:
add esp, 12
@Past:
pop ebx
pop esi
@Nil:
xor eax, eax
ret
@Continue:
cmp cl, [edx-2]
jz @Test2
cmp cl, [edx-1]
jnz @Loop
@Test1:
add edx, 1
@Test2:
add edx, -2
@Test0:
add edx, -1
@TestT:
mov esi, [esp]
test esi, esi
jz @Found
@String:
movzx ebx, word ptr [esi+eax]
cmp bx, word ptr [esi+edx+1]
jnz @AfterTestT
cmp esi, -2
jge @Found
movzx ebx, word ptr [esi+eax+2]
cmp bx, word ptr [esi+edx+3]
jnz @AfterTestT
add esi, 4
jl @String
@Found:
mov eax, [esp+4]
add edx, 2

cmp edx, [esp+8]
ja @Exit

add esp, 12
add eax, edx
pop ebx
pop esi
end;