diff --git a/math32.tal b/math32.tal
index 13feea8..e05d65b 100644
--- a/math32.tal
+++ b/math32.tal
@@ -112,8 +112,7 @@
 
 ( temporary registers )
 ( used by most operations, except mul32 and div32 )
-@sh [ &r $1
-      &x0 $1 &x1 $1 &x2 $1 &x3 $1
+@sh [ &x0 $1 &x1 $1 &x2 $1 &x3 $1
       &y0 $1 &y1 $1 &y2 $1 &y3 $1
       &z0 $1 &z1 $1 &z2 $1 &z3 $1
       &a0 $1 &a1 $1 &a2 $2 ]
@@ -171,36 +170,26 @@
 
 ( shift left by 0-7 bits )
 @left-shift0 ( x** n^ -> x<<n )
-    #0000 ;sh/z0 STA2 #0000 ;sh/z2 STA2
-    #40 SFT STH ( n<<4 -> r )
-    SWP SWP2 SWP ( x3 x2 x1 x0 )
-
-    STHkr SFT ;sh/z0 STA ( x3 x2 x1 )
-
-    #00 SWP STHkr SFT2 ( x3 x2 00x1<<r )
-    ;sh/z0 LDA2 ORA2 ;sh/z0 STA2 ( x3 x2 )
-
-    #00 SWP STHkr SFT2 ( x3 00x2<<r )
-    ;sh/z1 LDA2 ORA2 ;sh/z1 STA2 ( x3 )
-
-    #00 SWP STHr SFT2 ( 00x3<<r )
-    ;sh/z2 LDA2 ORA2 ;sh/z2 STA2 ( )
-
-    ;sh/z0 LDA2 ;sh/z2 LDA2
+    #40 SFT STH ( stash n<<4 )
+    #00 SWP STHkr SFT2                     ;sh/z2 STA2 ( store z2,z3 )
+    #00 SWP STHkr SFT2 #00 ;sh/z2 LDA ORA2 ;sh/z1 STA2 ( store z1,z2 )
+    #00 SWP STHkr SFT2 #00 ;sh/z1 LDA ORA2 ;sh/z0 STA2 ( store z0,z1 )
+            STHr  SFT      ;sh/z0 LDA ORA              ( calculate z0 )
+    ;sh/z1 LDA ;sh/z2 LDA2
     RTN
 
 ( shift left by 8-15 bits )
 @left-shift1 ( x** n^ -> x<<n )
     #0000 ;sh/z0 STA2 #00 ;sh/z2 STA
-    #08 SUB #40 SFT ;sh/r STA ( n<<4 -> r )
+    #08 SUB #40 SFT STH ( n<<4 -> r )
     SWP SWP2 SWP POP ( x3 x2 x1 )
 
-    ;sh/r LDA SFT ;sh/z0 STA ( x3 x2 )
+    STHkr SFT ;sh/z0 STA ( x3 x2 )
 
-    #00 SWP ;sh/r LDA SFT2 ( x3 00x2<<r )
+    #00 SWP STHkr SFT2 ( x3 00x2<<r )
     ;sh/z0 LDA2 ORA2 ;sh/z0 STA2 ( x3 )
 
-    #00 SWP ;sh/r LDA SFT2 ( 00x3<<r )
+    #00 SWP STHr SFT2 ( 00x3<<r )
     ;sh/z1 LDA2 ORA2 ;sh/z1 STA2 ( )
 
     ;sh/z0 LDA2 ;sh/z2 LDA #00
@@ -209,12 +198,12 @@
 ( shift left by 16-23 bits )
 @left-shift2 ( x** n^ -> x<<n )
     #0000 ;sh/z0 STA2
-    #10 SUB #40 SFT ;sh/r STA ( n<<4 -> r )
+    #10 SUB #40 SFT STH ( n<<4 -> r )
     SWP2 POP2 SWP ( x3 x2 )
 
-    ;sh/r LDA SFT ;sh/z0 STA ( x3 )
+    STHkr SFT ;sh/z0 STA ( x3 )
 
-    #00 SWP ;sh/r LDA SFT2 ( x3<<r )
+    #00 SWP STHr SFT2 ( x3<<r )
     ;sh/z0 LDA2 ORA2 ;sh/z0 STA2 (  )
 
     ;sh/z0 LDA2 #0000