feat(hints): add NewHint#53 (#1050)

* Add NewHint#53

* Update changelog

CHANGELOG.md

@@ -367,6 +367,15 @@
         %}
     ```
 
+* Add missing hint on vrf.json lib [#1050](https://github.com/lambdaclass/cairo-rs/pull/1050):
+
+    `BuiltinHintProcessor` now supports the following hint:
+
+    ```python
+        sum_low = ids.a.low + ids.b.low
+        ids.carry_low = 1 if sum_low >= ids.SHIFT else 0
+    ```
+
 * Add missing hint on uint256_improvements lib [#1016](https://github.com/lambdaclass/cairo-rs/pull/1016):
 
     `BuiltinHintProcessor` now supports the following hint:

cairo_programs/fq.cairo

@@ -155,18 +155,9 @@ namespace fq {
         alloc_locals;
         local res: Uint256;
         local carry_low: felt;
-        // unused. added to use UINT256_ADD
-        local carry_high: felt;
-        // this hint is not implemented:
-        // %{
-        //     sum_low = ids.a.low + ids.b.low
-        //     ids.carry_low = 1 if sum_low >= ids.SHIFT else 0
-        // %}
         %{
             sum_low = ids.a.low + ids.b.low
             ids.carry_low = 1 if sum_low >= ids.SHIFT else 0
-            sum_high = ids.a.high + ids.b.high + ids.carry_low
-            ids.carry_high = 1 if sum_high >= ids.SHIFT else 0
         %}
         // changed hint, no carry_high
         assert carry_low * carry_low = carry_low;

cairo_programs/fq_test.cairo

@@ -2,6 +2,30 @@
 
 from cairo_programs.fq import fq, Uint256, Uint512
 
+func test_add{range_check_ptr}() {
+    let a = Uint256(346, 0);
+    let b = Uint256(213, 0);
+
+    let res = fq.add(a, b);
+
+    assert res = Uint256(559, 0);
+
+    let a = Uint256(
+        154693353187447763037373048681595478410, 49972746532502551770198072697358847685
+    );
+    let b = Uint256(
+        103510830969771876705678198448587782120, 321696934602460025966614305804515599536
+    );
+
+    let res = fq.add(a, b);
+
+    assert res = Uint256(
+        258204184157219639743051247130183260530, 371669681134962577736812378501874447221
+    );
+
+    return ();
+}
+
 func test_u512_unsigned_div_rem{range_check_ptr}() {
     let x = Uint512(26362362, 32523523, 135525, 15521);
     let div = Uint256(1, 0);
@@ -58,6 +82,7 @@ func test_div{range_check_ptr}() {
 }
 
 func main{range_check_ptr}() {
+    test_add();
     test_u512_unsigned_div_rem();
     test_div();
 

src/hint_processor/builtin_hint_processor/builtin_hint_processor_definition.rs

@@ -362,7 +362,12 @@ impl HintProcessor for BuiltinHintProcessor {
             hint_code::DICT_SQUASH_UPDATE_PTR => {
                 dict_squash_update_ptr(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)
             }
-            hint_code::UINT256_ADD => uint256_add(vm, &hint_data.ids_data, &hint_data.ap_tracking),
+            hint_code::UINT256_ADD => {
+                uint256_add(vm, &hint_data.ids_data, &hint_data.ap_tracking, false)
+            }
+            hint_code::UINT256_ADD_LOW => {
+                uint256_add(vm, &hint_data.ids_data, &hint_data.ap_tracking, true)
+            }
             hint_code::UINT128_ADD => uint128_add(vm, &hint_data.ids_data, &hint_data.ap_tracking),
             hint_code::UINT256_SUB => uint256_sub(vm, &hint_data.ids_data, &hint_data.ap_tracking),
             hint_code::SPLIT_64 => split_64(vm, &hint_data.ids_data, &hint_data.ap_tracking),

src/hint_processor/builtin_hint_processor/hint_code.rs

@@ -301,6 +301,9 @@ ids.carry_low = 1 if sum_low >= ids.SHIFT else 0
 sum_high = ids.a.high + ids.b.high + ids.carry_low
 ids.carry_high = 1 if sum_high >= ids.SHIFT else 0"#;
 
+pub const UINT256_ADD_LOW: &str = r#"sum_low = ids.a.low + ids.b.low
+ids.carry_low = 1 if sum_low >= ids.SHIFT else 0"#;
+
 pub const UINT128_ADD: &str = r#"res = ids.a + ids.b
 ids.carry = 1 if res >= ids.SHIFT else 0"#;
 
@@ -1153,6 +1156,7 @@ from starkware.python.math_utils import div_mod, safe_div
 a = pack(ids.a, PRIME)
 b = pack(ids.b, PRIME)
 value = res = a - b"#;
+
 pub const EC_RECOVER_PRODUCT_MOD: &str = r#"from starkware.cairo.common.cairo_secp.secp_utils import pack
 from starkware.python.math_utils import div_mod, safe_div
 

src/hint_processor/builtin_hint_processor/uint256_utils.rs

@@ -100,38 +100,48 @@ impl<'a> From<Felt252> for Uint256<'a> {
 }
 
 /*
-Implements hint:
+Implements hints:
 %{
     sum_low = ids.a.low + ids.b.low
     ids.carry_low = 1 if sum_low >= ids.SHIFT else 0
     sum_high = ids.a.high + ids.b.high + ids.carry_low
     ids.carry_high = 1 if sum_high >= ids.SHIFT else 0
 %}
+%{
+    sum_low = ids.a.low + ids.b.low
+    ids.carry_low = 1 if sum_low >= ids.SHIFT else 0
+%}
 */
 pub fn uint256_add(
     vm: &mut VirtualMachine,
     ids_data: &HashMap<String, HintReference>,
     ap_tracking: &ApTracking,
+    low_only: bool,
 ) -> Result<(), HintError> {
     let shift = Felt252::new(1_u32) << 128_u32;
 
     let a = Uint256::from_var_name("a", vm, ids_data, ap_tracking)?;
     let b = Uint256::from_var_name("b", vm, ids_data, ap_tracking)?;
     let a_low = a.low.as_ref();
-    let a_high = a.high.as_ref();
     let b_low = b.low.as_ref();
-    let b_high = b.high.as_ref();
 
     // Main logic
     // sum_low = ids.a.low + ids.b.low
     // ids.carry_low = 1 if sum_low >= ids.SHIFT else 0
-    // sum_high = ids.a.high + ids.b.high + ids.carry_low
-    // ids.carry_high = 1 if sum_high >= ids.SHIFT else 0
-
     let carry_low = Felt252::from((a_low + b_low >= shift) as u8);
-    let carry_high = Felt252::from((a_high + b_high + &carry_low >= shift) as u8);
 
-    insert_value_from_var_name("carry_high", carry_high, vm, ids_data, ap_tracking)?;
+    if !low_only {
+        let a_high = a.high.as_ref();
+        let b_high = b.high.as_ref();
+
+        // Main logic
+        // sum_high = ids.a.high + ids.b.high + ids.carry_low
+        // ids.carry_high = 1 if sum_high >= ids.SHIFT else 0
+        let carry_high = Felt252::from((a_high + b_high + &carry_low >= shift) as u8);
+
+        insert_value_from_var_name("carry_high", carry_high, vm, ids_data, ap_tracking)?;
+    }
+
     insert_value_from_var_name("carry_low", carry_low, vm, ids_data, ap_tracking)
 }
 
@@ -508,6 +518,28 @@ mod tests {
         check_memory![vm.segments.memory, ((1, 12), 0), ((1, 13), 1)];
     }
 
+    #[test]
+    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+    fn run_uint256_add_low_only_ok() {
+        let hint_code =
+            "sum_low = ids.a.low + ids.b.low\nids.carry_low = 1 if sum_low >= ids.SHIFT else 0";
+        let mut vm = vm_with_range_check!();
+        //Initialize fp
+        vm.run_context.fp = 10;
+        //Create hint_data
+        let ids_data = non_continuous_ids_data![("a", -6), ("b", -4), ("carry_low", 2)];
+        vm.segments = segments![
+            ((1, 4), 2),
+            ((1, 5), 3),
+            ((1, 6), 4),
+            ((1, 7), ("340282366920938463463374607431768211455", 10))
+        ];
+        //Execute the hint
+        assert_matches!(run_hint!(vm, ids_data, hint_code), Ok(()));
+        //Check hint memory inserts
+        check_memory![vm.segments.memory, ((1, 12), 0)];
+    }
+
     #[test]
     #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
     fn run_uint128_add_ok() {

src/tests/cairo_run_test.rs

@@ -846,7 +846,7 @@ fn assert_le_felt_old() {
 #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
 fn cairo_run_fq_test() {
     let program_data = include_bytes!("../../cairo_programs/fq_test.json");
-    run_program_simple_with_memory_holes(program_data.as_slice(), 122);
+    run_program_simple_with_memory_holes(program_data.as_slice(), 120);
 }
 
 #[test]