Add missing methods to lambdaworks implementation (lambdaclass#1290)

* Add missing methods to lambdaworks impl

* Remove `modpow` and `to_signed_bytes_le` from lw-felt

* Add `From<&Big(U)Int>` to lw-felt
* Move comments out of `FeltOps` and remove trait

* Fix build

* Update changelog

* Uncomment deprecated tags

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 #### Upcoming Changes
 
+* fix: add `to_bytes_be` to the felt when `lambdaworks-felt` feature is active [#1290](https://github.com/lambdaclass/cairo-vm/pull/1290)
+
+* chore: mark `modpow` and `to_signed_bytes_le` as *deprecated* [#1290](https://github.com/lambdaclass/cairo-vm/pull/1290)
+
 * fix: bump *lambdaworks-math* to latest version, that fixes no-std support [#1293](https://github.com/lambdaclass/cairo-vm/pull/1293)
 
 * build: remove dependecy to `thiserror` (use `thiserror-no-std/std` instead)
@@ -13,8 +17,8 @@
 * feat: Add feature `lambdaworks-felt` to `felt` & `cairo-vm` crates [#1281](https://github.com/lambdaclass/cairo-rs/pull/1281)
 
     Changes under this feature:
-  * `Felt252` now uses _lambdaworks_' `FieldElement` internally
-  * BREAKING: some methods of `Felt252` were removed, namely: `modpow` and `to_bytes_be`
+  * `Felt252` now uses *LambdaWorks*' `FieldElement` internally
+  * BREAKING: some methods of `Felt252` were removed, namely: `modpow` and `to_signed_bytes_le`
 
 #### [0.7.0] - 2023-6-26
 

felt/src/lib_bigint_felt.rs

@@ -43,40 +43,10 @@ pub(crate) trait FeltOps {
     #[cfg(any(feature = "std", feature = "alloc"))]
     fn to_str_radix(&self, radix: u32) -> String;
 
-    /// Converts [`Felt252`] into a [`BigInt`] number in the range: `(- FIELD / 2, FIELD / 2)`.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// # use crate::cairo_felt::Felt252;
-    /// # use num_bigint::BigInt;
-    /// # use num_traits::Bounded;
-    /// let positive = Felt252::new(5);
-    /// assert_eq!(positive.to_signed_felt(), Into::<num_bigint::BigInt>::into(5));
-    ///
-    /// let negative = Felt252::max_value();
-    /// assert_eq!(negative.to_signed_felt(), Into::<num_bigint::BigInt>::into(-1));
-    /// ```
     fn to_signed_felt(&self) -> BigInt;
 
-    // Converts [`Felt252`]'s representation directly into a [`BigInt`].
-    // Equivalent to doing felt.to_biguint().to_bigint().
     fn to_bigint(&self) -> BigInt;
 
-    /// Converts [`Felt252`] into a [`BigUint`] number.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// # use crate::cairo_felt::Felt252;
-    /// # use num_bigint::BigUint;
-    /// # use num_traits::{Num, Bounded};
-    /// let positive = Felt252::new(5);
-    /// assert_eq!(positive.to_biguint(), Into::<num_bigint::BigUint>::into(5_u32));
-    ///
-    /// let negative = Felt252::max_value();
-    /// assert_eq!(negative.to_biguint(), BigUint::from_str_radix("800000000000011000000000000000000000000000000000000000000000000", 16).unwrap());
-    /// ```
     fn to_biguint(&self) -> BigUint;
 
     fn bits(&self) -> u64;
@@ -142,11 +112,14 @@ impl Felt252 {
     pub fn new<T: Into<Felt252>>(value: T) -> Self {
         value.into()
     }
+
+    #[deprecated]
     pub fn modpow(&self, exponent: &Felt252, modulus: &Felt252) -> Self {
         Self {
             value: self.value.modpow(&exponent.value, &modulus.value),
         }
     }
+
     pub fn iter_u64_digits(&self) -> U64Digits {
         self.value.iter_u64_digits()
     }
@@ -184,7 +157,9 @@ impl Felt252 {
     }
 
     #[cfg(any(feature = "std", feature = "alloc"))]
+    #[deprecated]
     pub fn to_signed_bytes_le(&self) -> Vec<u8> {
+        // NOTE: this is unsigned
         self.value.to_signed_bytes_le()
     }
     #[cfg(any(feature = "std", feature = "alloc"))]
@@ -207,16 +182,46 @@ impl Felt252 {
         self.value.to_str_radix(radix)
     }
 
+    /// Converts [`Felt252`] into a [`BigInt`] number in the range: `(- FIELD / 2, FIELD / 2)`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use crate::cairo_felt::Felt252;
+    /// # use num_bigint::BigInt;
+    /// # use num_traits::Bounded;
+    /// let positive = Felt252::new(5);
+    /// assert_eq!(positive.to_signed_felt(), Into::<num_bigint::BigInt>::into(5));
+    ///
+    /// let negative = Felt252::max_value();
+    /// assert_eq!(negative.to_signed_felt(), Into::<num_bigint::BigInt>::into(-1));
+    /// ```
     pub fn to_signed_felt(&self) -> BigInt {
         #[allow(deprecated)]
         self.value.to_signed_felt()
     }
 
+    // Converts [`Felt252`]'s representation directly into a [`BigInt`].
+    // Equivalent to doing felt.to_biguint().to_bigint().
     pub fn to_bigint(&self) -> BigInt {
         #[allow(deprecated)]
         self.value.to_bigint()
     }
 
+    /// Converts [`Felt252`] into a [`BigUint`] number.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use crate::cairo_felt::Felt252;
+    /// # use num_bigint::BigUint;
+    /// # use num_traits::{Num, Bounded};
+    /// let positive = Felt252::new(5);
+    /// assert_eq!(positive.to_biguint(), Into::<num_bigint::BigUint>::into(5_u32));
+    ///
+    /// let negative = Felt252::max_value();
+    /// assert_eq!(negative.to_biguint(), BigUint::from_str_radix("800000000000011000000000000000000000000000000000000000000000000", 16).unwrap());
+    /// ```
     pub fn to_biguint(&self) -> BigUint {
         #[allow(deprecated)]
         self.value.to_biguint()

felt/src/lib_lambdaworks.rs

@@ -148,7 +148,6 @@ impl From<bool> for Felt252 {
     }
 }
 
-// TODO: bury BigUint?
 impl From<BigUint> for Felt252 {
     fn from(mut value: BigUint) -> Self {
         if value >= *CAIRO_PRIME_BIGUINT {
@@ -163,7 +162,21 @@ impl From<BigUint> for Felt252 {
     }
 }
 
-// TODO: bury BigInt?
+impl From<&BigUint> for Felt252 {
+    fn from(value: &BigUint) -> Self {
+        if value >= &CAIRO_PRIME_BIGUINT {
+            Self::from(value.clone())
+        } else {
+            let mut limbs = [0; 4];
+            for (i, l) in (0..4).rev().zip(value.iter_u64_digits()) {
+                limbs[i] = l;
+            }
+            let value = FieldElement::new(UnsignedInteger::from_limbs(limbs));
+            Self { value }
+        }
+    }
+}
+
 // NOTE: used for deserialization
 impl From<BigInt> for Felt252 {
     fn from(value: BigInt) -> Self {
@@ -193,6 +206,11 @@ impl Felt252 {
         self.value.representative().limbs.into_iter().rev()
     }
 
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    pub fn to_bytes_be(&self) -> Vec<u8> {
+        self.to_be_bytes().to_vec()
+    }
+
     pub fn to_le_bytes(&self) -> [u8; 32] {
         // TODO: upstream should return array
         let mut bytes = [0; 32];