[commit: packages/array] master: Fix and simplify handling of Bool arrays (7adaf40)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/array

On branch  : master
Link       : http://git.haskell.org/packages/array.git/commitdiff/7adaf408cf24e420083f88ecd5b8d7bd7d0e5512

>---------------------------------------------------------------

commit 7adaf408cf24e420083f88ecd5b8d7bd7d0e5512
Author: Ben Gamari <ben at smart-cactus.org>
Date:   Tue Feb 7 21:32:29 2017 -0500

    Fix and simplify handling of Bool arrays
    
    No overflow check is necessary in the case of Bool arrays since the array size
    is actually smaller than the number of elements it contains. Moreover, we can
    use setByteArray# to initialize the array.


>---------------------------------------------------------------

7adaf408cf24e420083f88ecd5b8d7bd7d0e5512
 Data/Array/Base.hs | 41 +++++++++++------------------------------
 1 file changed, 11 insertions(+), 30 deletions(-)

diff --git a/Data/Array/Base.hs b/Data/Array/Base.hs
index 3bf861f..36db53f 100644
--- a/Data/Array/Base.hs
+++ b/Data/Array/Base.hs
@@ -1023,21 +1023,13 @@ instance MArray (STUArray s) Bool (ST s) where
     getNumElements (STUArray _ _ n _) = return n
     {-# INLINE newArray #-}
     newArray (l,u) initialValue = ST $ \s1# ->
-        case safeRangeSize (l,u)            of { n@(I# n#) ->
-        case newByteArray# (bOOL_SCALE n#) s1# of { (# s2#, marr# #) ->
-        case bOOL_WORD_SCALE n#         of { n'# ->
-#if __GLASGOW_HASKELL__ > 706
-        let loop i# s3# | isTrue# (i# ==# n'#) = s3#
-#else
-        let loop i# s3# | i# ==# n'#           = s3#
-#endif
-                        | otherwise            =
-                case writeWordArray# marr# i# e# s3# of { s4# ->
-                loop (i# +# 1#) s4# } in
-        case loop 0# s2#                of { s3# ->
+        case safeRangeSize (l,u)                   of { n@(I# n#) ->
+        case bOOL_SCALE n#                         of { nbytes# ->
+        case newByteArray# nbytes# s1#             of { (# s2#, marr# #) ->
+        case setByteArray# marr# 0# nbytes# e# s2# of { s3# ->
         (# s3#, STUArray l u n marr# #) }}}}
       where
-        !(W# e#) = if initialValue then maxBound else 0
+        !(I# e#) = if initialValue then 0xff else 0x0
     {-# INLINE unsafeNewArray_ #-}
     unsafeNewArray_ (l,u) = unsafeNewArraySTUArray_ (l,u) bOOL_SCALE
     {-# INLINE newArray_ #-}
@@ -1350,22 +1342,10 @@ instance MArray (STUArray s) Word64 (ST s) where
 -----------------------------------------------------------------------------
 -- Translation between elements and bytes
 
-bOOL_SCALE, bOOL_WORD_SCALE,
-  wORD_SCALE, dOUBLE_SCALE, fLOAT_SCALE :: Int# -> Int#
-bOOL_SCALE n#
-  | isTrue# (res# ># n#) = res#
-  | otherwise = error $ "Data.Array.Base.bOOL_SCALE: Overflow; n: "
-    ++ show (I# n#) ++ ", res: " ++ show (I# n#)
-  where
-    !(I# last#) = SIZEOF_HSWORD * 8 - 1
-    !res# = (n# +# last#) `uncheckedIShiftRA#` 3#
-bOOL_WORD_SCALE n#
-  | isTrue# (res# ># n#) = res#
-  | otherwise = error $ "Data.Array.Base.bOOL_WORD_SCALE: Overflow; n: "
-    ++ show (I# n#) ++ ", res: " ++ show (I# n#)
-  where
-    !(I# last#) = SIZEOF_HSWORD * 8 - 1
-    !res# = bOOL_INDEX (n# +# last#)
+bOOL_SCALE, wORD_SCALE, dOUBLE_SCALE, fLOAT_SCALE :: Int# -> Int#
+bOOL_SCALE n# =
+    -- + 7 to handle case where n is not divisible by 8
+    (n# +# 7#) `uncheckedIShiftRA#` 3#
 wORD_SCALE   n# = safe_scale scale# n# where !(I# scale#) = SIZEOF_HSWORD
 dOUBLE_SCALE n# = safe_scale scale# n# where !(I# scale#) = SIZEOF_HSDOUBLE
 fLOAT_SCALE  n# = safe_scale scale# n# where !(I# scale#) = SIZEOF_HSFLOAT
@@ -1379,8 +1359,9 @@ safe_scale scale# n#
     !res# = scale# *# n#
     !overflow = isTrue# (maxN# `divInt#` scale# <# n#)
     !(I# maxN#) = maxBound
+{-# INLINE safe_scale #-}
 
-
+-- | The index of the word which the given @Bool@ array elements falls within.
 bOOL_INDEX :: Int# -> Int#
 #if SIZEOF_HSWORD == 4
 bOOL_INDEX i# = i# `uncheckedIShiftRA#` 5#