[project @ 2002-02-05 17:32:24 by simonmar]

[haskell-directory.git] / GHC / Num.lhs

diff --git a/GHC/Num.lhs b/GHC/Num.lhs
index 611236c..52c2a7b 100644 (file)
--- a/GHC/Num.lhs
+++ b/GHC/Num.lhs
@@ -1,5 +1,5 @@
 % ------------------------------------------------------------------------------
-% $Id: Num.lhs,v 1.2 2001/07/31 13:09:11 simonmar Exp $
+% $Id: Num.lhs,v 1.4 2002/02/05 17:32:26 simonmar Exp $
 %
 % (c) The University of Glasgow, 1994-2000
 %
@@ -19,12 +19,12 @@ and the type
 {-# OPTIONS -fno-implicit-prelude #-}
 
 #include "MachDeps.h"
-#if WORD_SIZE_IN_BYTES == 4
+#if SIZEOF_HSWORD == 4
 #define LEFTMOST_BIT 2147483648
-#elif WORD_SIZE_IN_BYTES == 8
+#elif SIZEOF_HSWORD == 8
 #define LEFTMOST_BIT 9223372036854775808
 #else
-#error Please define LEFTMOST_BIT to be 2^(WORD_SIZE_IN_BYTES*8-1)
+#error Please define LEFTMOST_BIT to be 2^(SIZEOF_HSWORD*8-1)
 #endif
 
 module GHC.Num where
@@ -109,7 +109,13 @@ divModInt x@(I# _) y@(I# _) = (x `divInt` y, x `modInt` y)
 \begin{code}
 data Integer   
    = S# Int#                           -- small integers
+#ifndef ILX
    | J# Int# ByteArray#                        -- large integers
+#else
+   | J# Void BigInteger                 -- .NET big ints
+
+foreign type dotnet "BigInteger" BigInteger
+#endif
 \end{code}
 
 Convenient boxed Integer PrimOps. 
@@ -346,9 +352,9 @@ minusInteger i1@(J# _ _) i2@(S# _) = i1 - toBig i2
 minusInteger i1@(S# _) i2@(J# _ _) = toBig i1 - i2
 minusInteger (J# s1 d1) (J# s2 d2) = case minusInteger# s1 d1 s2 d2 of (# s, d #) -> J# s d
 
-timesInteger i1@(S# i) i2@(S# j)   = case mulIntC# i j of { (# r, c #) ->
-                                    if c ==# 0# then S# r
-                                    else toBig i1 * toBig i2 }
+timesInteger i1@(S# i) i2@(S# j)   = if   mulIntMayOflo# i j ==# 0#
+                                     then S# (i *# j)
+                                     else toBig i1 * toBig i2 
 timesInteger i1@(J# _ _) i2@(S# _) = i1 * toBig i2
 timesInteger i1@(S# _) i2@(J# _ _) = toBig i1 * i2
 timesInteger (J# s1 d1) (J# s2 d2) = case timesInteger# s1 d1 s2 d2 of (# s, d #) -> J# s d
@@ -376,33 +382,29 @@ instance  Enum Integer  where
     {-# INLINE enumFromThen #-}
     {-# INLINE enumFromTo #-}
     {-# INLINE enumFromThenTo #-}
-    enumFrom x             = efdInteger  x 1
-    enumFromThen x y       = efdInteger  x (y-x)
-    enumFromTo x lim      = efdtInteger x 1     lim
-    enumFromThenTo x y lim = efdtInteger x (y-x) lim
-
-
-efdInteger  = enumDeltaIntegerList
-efdtInteger = enumDeltaToIntegerList
+    enumFrom x             = enumDeltaInteger  x 1
+    enumFromThen x y       = enumDeltaInteger  x (y-x)
+    enumFromTo x lim      = enumDeltaToInteger x 1     lim
+    enumFromThenTo x y lim = enumDeltaToInteger x (y-x) lim
 
 {-# RULES
-"efdInteger"           forall x y.  efdInteger x y         = build (\c _ -> enumDeltaIntegerFB c x y)
-"efdtInteger"          forall x y l.efdtInteger x y l      = build (\c n -> enumDeltaToIntegerFB c n x y l)
-"enumDeltaInteger"     enumDeltaIntegerFB   (:)    = enumDeltaIntegerList
-"enumDeltaToInteger"   enumDeltaToIntegerFB (:) [] = enumDeltaToIntegerList
+"enumDeltaInteger"     [~1] forall x y.  enumDeltaInteger x y     = build (\c _ -> enumDeltaIntegerFB c x y)
+"efdtInteger"          [~1] forall x y l.enumDeltaToInteger x y l = build (\c n -> enumDeltaToIntegerFB c n x y l)
+"enumDeltaInteger"     [1] enumDeltaIntegerFB   (:)    = enumDeltaInteger
+"enumDeltaToInteger"   [1] enumDeltaToIntegerFB (:) [] = enumDeltaToInteger
  #-}
 
 enumDeltaIntegerFB :: (Integer -> b -> b) -> Integer -> Integer -> b
 enumDeltaIntegerFB c x d = x `c` enumDeltaIntegerFB c (x+d) d
 
-enumDeltaIntegerList :: Integer -> Integer -> [Integer]
-enumDeltaIntegerList x d = x : enumDeltaIntegerList (x+d) d
+enumDeltaInteger :: Integer -> Integer -> [Integer]
+enumDeltaInteger x d = x : enumDeltaInteger (x+d) d
 
 enumDeltaToIntegerFB c n x delta lim
   | delta >= 0 = up_fb c n x delta lim
   | otherwise  = dn_fb c n x delta lim
 
-enumDeltaToIntegerList x delta lim
+enumDeltaToInteger x delta lim
   | delta >= 0 = up_list x delta lim
   | otherwise  = dn_list x delta lim
 
@@ -436,7 +438,10 @@ dn_list x delta lim = go (x::Integer)
 \begin{code}
 instance Show Integer where
     showsPrec p n r
-        | n < 0 && p > 6 = '(' : jtos n (')' : r)
+        | p > 6 && n < 0 = '(' : jtos n (')' : r)
+               -- Minor point: testing p first gives better code 
+               -- in the not-uncommon case where the p argument
+               -- is a constant
         | otherwise      = jtos n r
     showList = showList__ (showsPrec 0)