HaskellWorks.Data.Bits.Broadword.Word32

Documentation

h :: Int -> Word32

Initialise all sub-words of size k where k ∈ { 2, 4, 8, 16, 32 } such that the highest bit is set to 1 and all other bits are cleared.

>>> import Numeric(showHex)
>>> showHex (h 2) ""
"aaaaaaaa"
>>> showHex (h 4) ""
"88888888"
>>> showHex (h 8) ""
"80808080"
>>> showHex (h 16) ""
"80008000"
>>> showHex (h 32) ""
"80000000"

l :: Int -> Word32

Initialise all sub-words of size k where k ∈ { 2, 4, 8, 16, 32 } such that the lowest bit is set to 1 and all other bits are cleared.

>>> import Numeric(showHex)
>>> showHex (l 2) ""
"55555555"
>>> showHex (l 4) ""
"11111111"
>>> showHex (l 8) ""
"1010101"
>>> showHex (l 16) ""
"10001"
>>> showHex (l 32) ""
"1"

kBitDiff :: Int -> Word32 -> Word32 -> Word32

Broadword subtraction of sub-words of size k where k ∈ { 2, 4, 8, 16, 32 }.

The subtraction respects 2's complement so sub-words may be regarded as signed or unsigned words.

>>> import Numeric(showHex)
>>> showHex (kBitDiff 8 0x04030201 0x02020101) ""
"2010100"
>>> showHex (kBitDiff 8 0x04030201 0x01020304) ""
"301fffd"
>>> showHex (kBitDiff 8 0x200000ff 0x100000ff) ""
"10000000"

kBitDiffPos :: Int -> Word32 -> Word32 -> Word32

Broadword subtraction of sub-words of size k where k ∈ { 2, 4, 8, 16, 32 } where results are bounded from below by 0.

>>> import Numeric(showHex)
>>> showHex (kBitDiffPos 8 0x04030201 0x02020101) ""
"2010100"
>>> showHex (kBitDiffPos 8 0x04030201 0x01020304) ""
"3010000"
>>> showHex (kBitDiffPos 8 0x200000ff 0x100000ff) "" -- produces nonsense in the last sub-word
"10000000"

kBitDiffUnsafe :: Int -> Word32 -> Word32 -> Word32

Broadword subtraction of sub-words of size k where k ∈ { 2, 4, 8, 16, 32 } where all the sub-words of x and y must not have the signed bit set for the result to be meaningful.

>>> import Numeric(showHex)
>>> showHex (kBitDiffUnsafe 8 0x04030201 0x02020101) ""
"2010100"
>>> showHex (kBitDiffUnsafe 8 0x04030201 0x05060708) ""
"fffdfbf9"
>>> showHex (kBitDiffUnsafe 8 0x200000ff 0x100000ff) ""
"10000080"