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Fix: changed endian syntax to le/be #362

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Sep 22, 2023
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Fix: changed endian syntax to le/be #362

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14 changes: 7 additions & 7 deletions crates/utils/src/helpers.cairo
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Original file line number Diff line number Diff line change
Expand Up @@ -71,12 +71,12 @@ fn pow256_rev(i: usize) -> u256 {

/// Splits a u256 into `len` bytes, big-endian, and appends the result to `dst`.
fn split_word(mut value: u256, mut len: usize, ref dst: Array<u8>) {
let little_endian = split_word_little(value, len);
let big_endian = ArrayExtensionTrait::reverse(little_endian.span());
ArrayExtensionTrait::concat(ref dst, big_endian.span());
let word_le = split_word_le(value, len);
let word_be = ArrayExtensionTrait::reverse(word_le.span());
ArrayExtensionTrait::concat(ref dst, word_be.span());
}

fn split_u128_little(ref dest: Array<u8>, mut value: u128, mut len: usize) {
fn split_u128_le(ref dest: Array<u8>, mut value: u128, mut len: usize) {
loop {
if len == 0 {
assert(value == 0, 'split_words:value not 0');
Expand All @@ -89,12 +89,12 @@ fn split_u128_little(ref dest: Array<u8>, mut value: u128, mut len: usize) {
}

/// Splits a u256 into `len` bytes, little-endian, and returns the bytes array.
fn split_word_little(mut value: u256, mut len: usize) -> Array<u8> {
fn split_word_le(mut value: u256, mut len: usize) -> Array<u8> {
let mut dst: Array<u8> = ArrayTrait::new();
let low_len = min(len, 16);
split_u128_little(ref dst, value.low, low_len);
split_u128_le(ref dst, value.low, low_len);
let high_len = min(len - low_len, 16);
split_u128_little(ref dst, value.high, high_len);
split_u128_le(ref dst, value.high, high_len);
dst
}

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12 changes: 6 additions & 6 deletions crates/utils/src/tests/test_helpers.cairo
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Original file line number Diff line number Diff line change
Expand Up @@ -69,24 +69,24 @@ fn test_load_word() {

#[test]
#[available_gas(2000000000)]
fn test_split_word_little() {
fn test_split_word_le() {
// Test with 0 value and 0 len
let res0 = helpers::split_word_little(0, 0);
let res0 = helpers::split_word_le(0, 0);
assert(res0.len() == 0, 'res0: wrong length');

// Test with single byte value
let res1 = helpers::split_word_little(1, 1);
let res1 = helpers::split_word_le(1, 1);
assert(res1.len() == 1, 'res1: wrong length');
assert(*res1[0] == 1, 'res1: wrong value');

// Test with two byte value
let res2 = helpers::split_word_little(257, 2); // 257 = 0x0101
let res2 = helpers::split_word_le(257, 2); // 257 = 0x0101
assert(res2.len() == 2, 'res2: wrong length');
assert(*res2[0] == 1, 'res2: wrong value at index 0');
assert(*res2[1] == 1, 'res2: wrong value at index 1');

// Test with four byte value
let res3 = helpers::split_word_little(67305985, 4); // 67305985 = 0x04030201
let res3 = helpers::split_word_le(67305985, 4); // 67305985 = 0x04030201
assert(res3.len() == 4, 'res3: wrong length');
assert(*res3[0] == 1, 'res3: wrong value at index 0');
assert(*res3[1] == 2, 'res3: wrong value at index 1');
Expand All @@ -95,7 +95,7 @@ fn test_split_word_little() {

// Test with 16 byte value (u128 max value)
let max_u128: u256 = 340282366920938463463374607431768211454; // u128 max value - 1
let res4 = helpers::split_word_little(max_u128, 16);
let res4 = helpers::split_word_le(max_u128, 16);
assert(res4.len() == 16, 'res4: wrong length');
assert(*res4[0] == 0xfe, 'res4: wrong MSB value');

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