r926 - cpu/x86

Author: wmb
Date: 2008-09-09 03:55:47 +0200 (Tue, 09 Sep 2008)
New Revision: 926

Modified:
   cpu/x86/kerncode.fth
Log:
Added bskip and lskip primitives to speed up bitmap searching for ext2.

Modified: cpu/x86/kerncode.fth
===================================================================
--- cpu/x86/kerncode.fth	2008-09-08 23:30:08 UTC (rev 925)
+++ cpu/x86/kerncode.fth	2008-09-09 01:55:47 UTC (rev 926)
@@ -551,6 +551,31 @@
    dx di mov
 c;

+\ Skip initial occurrences of bvalue, returning the residual length
+code bskip  ( adr len bvalue -- residue )
+   di dx mov
+   ax pop         \ BX: compare value
+   cx pop         \ CX: Length
+   di pop         \ SI: address
+   cld  repz byte scas
+   <>  if  cx inc  then
+   dx di mov
+   cx push
+c;
+
+\ Skip initial occurrences of lvalue, returning the residual length
+code lskip  ( adr len lvalue -- residue )
+   di dx mov
+   ax pop         \ BX: compare value
+   cx pop         \ CX: Length
+   2 # cx shr     \ Convert CX to longword count
+   di pop         \ SI: address
+   cld  repz scas
+   <>  if  cx inc  then
+   dx di mov
+   2 # cx shl  cx push
+c;
+
 code noop (s -- )  c;

code n->l (s n.unsigned -- l ) c;