HaskellWorks.Data.Bits.Broadword.Word64

Documentation

h :: Int -> Word64

Initialise all sub-words of size k where k ∈ { 2, 4, 8, 16, 32, 64 } such that the highest bit is set to 1 and all other bits are cleared.

>>> import Numeric(showHex)
>>> showHex (h 2) ""
"aaaaaaaaaaaaaaaa"
>>> showHex (h 4) ""
"8888888888888888"
>>> showHex (h 8) ""
"8080808080808080"
>>> showHex (h 16) ""
"8000800080008000"
>>> showHex (h 32) ""
"8000000080000000"
>>> showHex (h 64) ""
"8000000000000000"

l :: Int -> Word64

Initialise all sub-words of size k where k ∈ { 2, 4, 8, 16, 32, 64 } such that the lowest bit is set to 1 and all other bits are cleared.

>>> import Numeric(showHex)
>>> showHex (l 2) ""
"5555555555555555"
>>> showHex (l 4) ""
"1111111111111111"
>>> showHex (l 8) ""
"101010101010101"
>>> showHex (l 16) ""
"1000100010001"
>>> showHex (l 32) ""
"100000001"
>>> showHex (l 64) ""
"1"

kBitDiff :: Int -> Word64 -> Word64 -> Word64

Broadword subtraction of sub-words of size k where k ∈ { 2, 4, 8, 16, 32, 64 }.

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

>>> import Numeric(showHex)
>>> showHex (kBitDiff 8 0x0807060504030201 0x0404030302020101) ""
"403030202010100"
>>> showHex (kBitDiff 8 0x0807060504030201 0x0102030405060708) ""
"7050301fffdfbf9"
>>> showHex (kBitDiff 8 0x20000000000000ff 0x10000000000000ff) ""
"1000000000000000"

kBitDiffPos :: Int -> Word64 -> Word64 -> Word64

Broadword subtraction of sub-words of size k where k ∈ { 2, 4, 8, 16, 32, 64 } where results are bounded from below by 0.

>>> import Numeric(showHex)
>>> showHex (kBitDiffPos 8 0x0807060504030201 0x0404030302020101) ""
"403030202010100"
>>> showHex (kBitDiffPos 8 0x0807060504030201 0x0102030405060708) ""
"705030100000000"
>>> showHex (kBitDiffPos 8 0x20000000000000ff 0x10000000000000ff) ""
"1000000000000000"

kBitDiffUnsafe :: Int -> Word64 -> Word64 -> Word64

Broadword subtraction of sub-words of size k where k ∈ { 2, 4, 8, 16, 32, 64 } 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 0x0807060504030201 0x0404030302020101) ""
"403030202010100"
>>> showHex (kBitDiffUnsafe 8 0x0807060504030201 0x0102030405060708) ""
"7050301fffdfbf9"
>>> showHex (kBitDiffUnsafe 8 0x20000000000000ff 0x10000000000000ff) "" -- produces nonsense in the last sub-word
"1000000000000080"