+ added i8086 asm optimized IndexByte routine

git-svn-id: trunk@31947 -

rtl/i8086/i8086.inc

@@ -160,6 +160,43 @@ end;
 {$endif FPC_SYSTEM_HAS_MOVE}
 
 
+{$ifndef FPC_SYSTEM_HAS_INDEXBYTE}
+{$define FPC_SYSTEM_HAS_INDEXBYTE}
+function IndexByte(Const buf;len:SizeInt;b:byte):SizeInt; assembler; nostackframe;
+asm
+  mov bx, sp
+  mov cx, ss:[bx + 4 + extra_param_offset]  // len
+  or cx, cx
+  jle @@NotFound
+{$ifdef FPC_X86_DATA_NEAR}
+  mov di, ss:[bx + 6 + extra_param_offset]  // @buf
+  mov ax, ds
+  mov es, ax
+{$else FPC_X86_DATA_NEAR}
+  les di, ss:[bx + 6 + extra_param_offset]  // @buf
+{$endif FPC_X86_DATA_NEAR}
+  mov si, di  // save the start of the buffer in si
+  mov al, ss:[bx + 2 + extra_param_offset]  // b
+{$ifdef FPC_ENABLED_CLD}
+  cld
+{$endif FPC_ENABLED_CLD}
+  repne scasb
+  je @@Found
+@@NotFound:
+  mov ax, 0FFFFh  // return -1
+  jmp @@Done
+@@Found:
+  sub di, si
+  xchg ax, di
+  dec ax
+{$if defined(FPC_X86_DATA_FAR) or defined(FPC_X86_DATA_HUGE)}
+  mov dx, es
+{$endif}
+@@Done:
+end;
+{$endif FPC_SYSTEM_HAS_INDEXBYTE}
+
+
 {$define FPC_SYSTEM_HAS_SPTR}
 Function Sptr : Pointer;assembler;nostackframe;
 asm