Copyright	(c) 2025 Jared Tobin
License	MIT
Maintainer	Jared Tobin <jared@ppad.tech>
Safe Haskell	None
Language	Haskell2010

Data.Word.Limb

Contents

Limb
Bit manipulation and representation
Comparison
Selection
Negation
Arithmetic

Description

The primitive Limb type, as well as operations on it.

Synopsis

newtype Limb :: TYPE 'WordRep = Limb Word#
render :: Limb -> String
and# :: Limb -> Limb -> Limb
or# :: Limb -> Limb -> Limb
not# :: Limb -> Limb
xor# :: Limb -> Limb -> Limb
bits# :: Limb -> Int
shl# :: Limb -> Int# -> Limb
shl1# :: Limb -> (# Limb, Limb #)
shr# :: Limb -> Int# -> Limb
shr1# :: Limb -> (# Limb, Limb #)
eq# :: Limb -> Limb -> Choice
ne# :: Limb -> Limb -> Choice
eq_vartime# :: Limb -> Limb -> Bool
ne_vartime# :: Limb -> Limb -> Bool
nonzero# :: Limb -> Choice
lt# :: Limb -> Limb -> Choice
gt# :: Limb -> Limb -> Choice
select# :: Limb -> Limb -> Choice -> Limb
cswap# :: Limb -> Limb -> Choice -> (# Limb, Limb #)
neg# :: Limb -> Limb
add_o# :: Limb -> Limb -> (# Limb, Limb #)
add_c# :: Limb -> Limb -> Limb -> (# Limb, Limb #)
add_w# :: Limb -> Limb -> Limb
add_s# :: Limb -> Limb -> Limb
sub_b# :: Limb -> Limb -> Limb -> (# Limb, Limb #)
sub_w# :: Limb -> Limb -> Limb
sub_s# :: Limb -> Limb -> Limb
mul_c# :: Limb -> Limb -> (# Limb, Limb #)
mul_w# :: Limb -> Limb -> Limb
mul_s# :: Limb -> Limb -> Limb
mac# :: Limb -> Limb -> Limb -> Limb -> (# Limb, Limb #)

Limb

newtype Limb :: TYPE 'WordRep Source #

A Limb is the smallest component of a wider word.

Constructors

Limb Word#

render :: Limb -> String Source #

Return a Limb value as a String.

Bit manipulation and representation

and# Source #

Arguments

:: Limb	a
-> Limb	b
-> Limb	a & b

Bitwise and.

or# Source #

Arguments

:: Limb	a
-> Limb	b
-> Limb	a \| b

Bitwise or.

not# Source #

Arguments

:: Limb	a
-> Limb	not a

Bitwise not.

xor# Source #

Arguments

:: Limb	a
-> Limb	b
-> Limb	a ^ b

Bitwise exclusive or.

bits# Source #

Arguments

:: Limb	limb
-> Int	bits required to represent limb

Number of bits required to represent this limb.

shl# Source #

Arguments

:: Limb	limb
-> Int#	shift amount
-> Limb	result

Bit-shift left.

shl1# :: Limb -> (# Limb, Limb #) Source #

Bit-shift left by 1, returning the result and carry.

shr# Source #

Arguments

:: Limb	limb
-> Int#	shift amount
-> Limb	result

Bit-shift right.

shr1# :: Limb -> (# Limb, Limb #) Source #

Bit-shift right by 1, returning the result and carry.

Comparison

eq# :: Limb -> Limb -> Choice Source #

Equality comparison.

ne# :: Limb -> Limb -> Choice Source #

Inequality comparison.

eq_vartime# :: Limb -> Limb -> Bool Source #

ne_vartime# :: Limb -> Limb -> Bool Source #

nonzero# :: Limb -> Choice Source #

Comparison to zero.

lt# :: Limb -> Limb -> Choice Source #

Less than.

gt# :: Limb -> Limb -> Choice Source #

Greater than.

Selection

select# Source #

Arguments

:: Limb	a
-> Limb	b
-> Choice	c
-> Limb	result

Return a if c is truthy, otherwise return b.

cswap# Source #

Arguments

:: Limb	a
-> Limb	b
-> Choice	c
-> (# Limb, Limb #)	result

Return (# b, a #) if c is truthy, otherwise return (# a, b #).

Negation

neg# :: Limb -> Limb Source #

Wrapping (two's complement) negation.

Arithmetic

add_o# Source #

Arguments

:: Limb	augend
-> Limb	addend
-> (# Limb, Limb #)	(# sum, carry #)

Overflowing addition, computing augend + addend, returning the sum and carry.

add_c# Source #

Arguments

:: Limb	augend
-> Limb	addend
-> Limb	carry
-> (# Limb, Limb #)	(# sum, new carry #)

Carrying addition, computing augend + addend + carry, returning the sum and new carry.

add_w# Source #

Arguments

:: Limb	augend
-> Limb	addend
-> Limb	sum

Wrapping addition, computing augend + addend, returning the sum (discarding overflow).

add_s# :: Limb -> Limb -> Limb Source #

Saturating addition, computing augend + addend, returning the sum (clamping to the maximum representable value in the case of overflow).

sub_b# Source #

Arguments

:: Limb	minuend
-> Limb	subtrahend
-> Limb	borrow
-> (# Limb, Limb #)	(# difference, new borrow #)

Borrowing subtraction, computing minuend - (subtrahend + borrow), returning the difference and new borrow mask.

sub_w# Source #

Arguments

:: Limb	minuend
-> Limb	subtrahend
-> Limb	difference

Wrapping subtraction, computing minuend - subtrahend, returning the difference (and discarding underflow).

sub_s# Source #

Arguments

:: Limb	minuend
-> Limb	subtrahend
-> Limb	difference

Saturating subtraction, computing minuend - subtrahend, returning the difference (and clamping to zero in the case of underflow).

mul_c# Source #

Arguments

:: Limb	multiplicand
-> Limb	multiplier
-> (# Limb, Limb #)	(# low, high #) product

Widening multiplication, returning low and high words of the product.

mul_w# Source #

Arguments

:: Limb	multiplicand
-> Limb	multiplier
-> Limb	low word of product

Wrapping multiplication, returning only the low word of the product.

mul_s# Source #

Arguments

:: Limb	multiplicand
-> Limb	multiplier
-> Limb	clamped low word of product

Saturating multiplication, returning only the low word of the product, and clamping to the maximum value in the case of overflow.

mac# Source #

Arguments

:: Limb	a (multiplicand)
-> Limb	b (multiplier)
-> Limb	m (addend)
-> Limb	c (carry)
-> (# Limb, Limb #)	a * b + m + c

Multiply-add-carry, computing a * b + m + c, returning the result along with the new carry.