✨ A collection of useful functions in Cairo

Get Sphinx

To install the library through protostar, you can just run the following command:

protostar install https://github.com/Th0rgal/sphinx

Otherwise, you can just copy the files that you need. You can do whatever you want with the code and you don't have to give me credit for it, it's MIT licensed.

Features

Functional

File: functional.cairo Some functions applying operations from other functions passed in parameter. They are inspired by the standard OCAML library.

note: new(x, y, z, ...) will create an array, link to the docs

List.fold_left

Takes a function, an accumulator and a list. It will apply the function to the accumulator and an element of the list to get the new accumulator until reaching the end.

# a sum which adds two elements
func sum(
    acc : felt, value : felt
) -> (output : felt):
    return (acc + value)
end

# a sum which adds all elements from a list using fold_left and sum
@view
func test_fold_left():
    let (result) = List.fold_left(sum, 0, 5, new (5, 4, 3, 2, 1))
    assert result = 15
    return ()
end

List.exists / List.for_all

These functions are equivalent to quantifiers for_all and exists in mathematics. Given a list of elements, for_all will return true if and only if all these elements respect a property given in parameter while exists will return true if there is at least one element respecting the property.

func is_4(item : felt) -> (
    bool : felt
):
    if item == 4:
        return (TRUE)
    end
    return (FALSE)
end

@view
func test_exists():
    alloc_locals
    let (arr : felt*) = new (5, 4, 3, 2, 1)
    let (result) = List.exists(is_4, 5, arr)
    assert result = TRUE
    return ()
end

@view
func test_for_all():
    alloc_locals
    let (arr : felt*) = alloc()
    assert arr[0] = 5
    assert arr[1] = 4
    assert arr[2] = 3
    assert arr[3] = 2
    assert arr[4] = 1
    let (result) = List.for_all(is_4, 5, arr)
    assert result = FALSE
    let (result) = List.for_all(is_not_10, 5, arr)
    assert result = TRUE
    return ()
end

Storage

File: storage.cairo Write to a storage_variable from its address.

Storage.write, Storage.read

@storage_var
func my_var(x : felt, y : felt) -> (a : felt):
end

@view
func test_my_var{syscall_ptr : felt*, range_check_ptr, pedersen_ptr : HashBuiltin*}():
    alloc_locals
    let (inputs) = alloc()
    assert inputs[0] = 7
    assert inputs[1] = 6
    Storage.write(my_var.addr, 2, inputs, 'hello')

    let (result) = my_var.read(7, 6)
    assert result = 'hello'

    let (storage_result) = Storage.read(my_var.addr, 2, inputs)
    assert storage_result = 'hello'
    return ()
end

SHA256

File: sha256.cairo This file depends on bits.cairo. It allows to calculate the sha256 hash of an input of any size in bits. For example, sha256("hey guys") = "be83351937c9a13e0d0e16ae97ee46915e790cf9a5d55fa317014539009f2101" Which if broken down into 32-bit words, gives :

3196269849
935960894
219027118
2548975249
1584991481
2782224291
385959225
10428673

@view
func test_sha256{bitwise_ptr : BitwiseBuiltin*, range_check_ptr}():

    # let's hash "hey guys"
    let (hash) = sha256(new ('hey ', 'guys'), 64)
    let a = hash[0]
    assert a = 3196269849
    let b = hash[1]
    assert b = 935960894
    let c = hash[2]
    assert c = 219027118
    let d = hash[3]
    assert d = 2548975249
    let e = hash[4]
    assert e = 1584991481
    let f = hash[5]
    assert f = 2782224291
    let g = hash[6]
    assert g = 385959225
    let h = hash[7]
    assert h = 10428673

    return ()
end

Bits manipulation

File: bits.cairo This file allows to represent long lists of bits and to perform common operations on them. This list will be represented by a list of words (felts) each containing up to 32 bits, and a felt containing the total number of bits.

Bits.extract

Write len bits from input to output, starting at start.

@view
func test_extract{range_check_ptr}():
    alloc_locals
    let (input) = alloc()
    # 01001000011001010110110001101100
    assert input[0] = 1214606444
    # 01101111001000000111011101101111
    assert input[1] = 1864398703
    # 01110010011011000110010000000000
    assert input[2] = 1919706112

    # two words, no shift, len = two words
    let (output) = alloc()
    Bits.extract(input, 0, 64, output)
    # 01001000011001010110110001101100
    assert output[0] = 1214606444
    # 01101111001000000111011101101111
    assert output[1] = 1864398703

    return ()
end

Bits.merge

Allows to merge two lists of bits into one.

Bits.rightshift

Allows you to apply a binary rightshift to a word.

Bits.leftshift

Allows you to apply a binary leftship to a word.

Bits.rightrotate

Allows you to shift the bits to the right and return by the left to a word.

Bits.negate

Returns the binary negation of a word.

th0rgal / sphinx Goto Github PK

sphinx's Introduction

✨ A collection of useful functions in Cairo

Get Sphinx

Features

Functional

List.fold_left

List.exists / List.for_all

Storage

Storage.write, Storage.read

SHA256

Bits manipulation

Bits.extract

Bits.merge

Bits.rightshift

Bits.leftshift

Bits.rightrotate

Bits.negate

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