Vorkommen eines SubStrings in einem String

[sakura]

Die folgende Methode gibt die Anzahl des vollständigen Auftreten eines SubStrings in einem String zurück. (getestet in Delphi 5 - 7)

Delphi-Quellcode:

function CountSubStrings(SubStr, Str: AnsiString): DWORD;
type
  StrRec = packed record
    allocSiz: Longint;
    refCnt: Longint;
    length: Longint;
  end;
const
  skew = sizeof(StrRec);
var
  Count, SubLength: Integer;
asm
  // Search-String passed?
  TEST    EAX,EAX
  JE      @@noWork

  // Sub-String passed?
  TEST    EDX,EDX
  JE      @@stringEmpty

  // Save registers affected
  PUSH    ECX
  PUSH    EBX
  PUSH    EDI
  PUSH    ESI

  // Load Sub-String pointer
  MOV     ESI,EAX
  // Load Search-String pointer
  MOV     EDI,EDX
  // Save Last Position in EBX
  MOV     EBX,ECX

  // Get Search-String Length
  MOV     ECX,[EDI-skew].StrRec.length

  // Get Sub-String Length
  MOV     EAX,[ESI-skew].StrRec.length
  // Adjust
  DEC     EAX
  MOV     SubLength,EAX
  // Failed if Sub-String Length was zero
  JS      @@exit

  XOR     EDX,EDX
  MOV     Count,EDX
  // Load character count to be scanned
  SUB     ECX,EAX
  // Failed if Sub-String was equal or longer than Search-String
  JLE     @@exit
  // Pull first character of Sub-String for SCASB function
  MOV     AL,[ESI]
  // Point to second character for CMPSB function
  INC     ESI
@@loop:
  // Scan for first matching character
  REPNE   SCASB
  // Failed, if none are matching
  JNE     @@exit
  // Save counter
  MOV     EBX,ECX
  // load Sub-String length
  MOV     ECX,SubLength
  PUSH    ESI
  PUSH    EDI
  // compare all bytes until one is not equal
  REPE    CMPSB
  // restore counter
  POP     EDI
  POP     ESI
  // restore counter
  MOV     ECX,EBX
  // all byte were equal, search is completed
  JE      @@found
  // continue search
  JMP     @@loop
@@found:
  // increment found counter
  MOV     EBX,SubLength
  ADD     EDI,EBX
  INC     Count
  JMP     @@loop
@@stringEmpty:
  // return zero - no match
  XOR     EDX,EDX
  JMP     @@noWork
@@exit:
  // restore registers
  POP     ESI
  POP     EDI
  POP     EBX
  POP     ECX
  MOV     EAX,Count
@@noWork:
end;

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