checksums.superfast: reuse code and make a bit faster.

basis/checksums/superfast/superfast.factor

@@ -1,10 +1,9 @@
 ! Copyright (C) 2013 John Benediktsson.
 ! See http://factorcode.org/license.txt for BSD license.
 
-USING: accessors alien alien.data byte-arrays checksums
-combinators fry grouping io.binary kernel math math.bitwise
-math.ranges sequences sequences.private ;
-QUALIFIED-WITH: alien.c-types c
+USING: accessors alien alien.c-types alien.data byte-arrays
+checksums combinators fry grouping io.binary kernel math
+math.bitwise math.ranges sequences sequences.private ;
 
 IN: checksums.superfast
 
@@ -15,23 +14,21 @@ C: <superfast> superfast
 
 : 32-bit ( n -- n' ) 32 on-bits mask ; inline
 
+: (main-loop) ( hash m n -- hash' )
+    [ + ] [ 11 shift dupd bitxor ] bi*
+    [ 16 shift ] [ bitxor ] bi* 32-bit
+    [ -11 shift ] [ + ] bi ; inline
+
 : main-loop ( seq hash -- seq hash' )
     over byte-array? little-endian? and [
-        [ 0 over length 4 - 4 <range> ] dip
-        [
-            pick
-            [ <displaced-alien> c:short deref ]
-            [ [ 2 + ] dip <displaced-alien> c:short deref ] 2bi
-            [ + ] [ 11 shift dupd bitxor ] bi*
-            [ 16 shift ] [ bitxor ] bi* 32-bit
-            [ -11 shift ] [ + ] bi
+        [ 0 over length 4 - 4 <range> ] dip [
+            pick <displaced-alien> int deref
+            [ 16 on-bits mask ] [ -16 shift ] bi
+            (main-loop)
         ] reduce
     ] [
         [ dup length 4 mod dupd head-slice* 4 <groups> ] dip [
-            2 cut-slice
-            [ le> + ] [ le> 11 shift dupd bitxor ] bi*
-            [ 16 shift ] [ bitxor ] bi* 32-bit
-            [ -11 shift ] [ + ] bi
+            2 cut-slice [ le> ] bi@ (main-loop)
         ] reduce
     ] if ; inline