Add NewHint#13

cairo_programs/quad_bit.cairo

@@ -0,0 +1,31 @@
+%builtins range_check
+
+func get_quad_bit{range_check_ptr}(scalar_u: felt, scalar_v: felt, m: felt) -> felt {
+    alloc_locals;
+    local quad_bit: felt;
+    %{
+        ids.quad_bit = (
+            8 * ((ids.scalar_v >> ids.m) & 1)
+            + 4 * ((ids.scalar_u >> ids.m) & 1)
+            + 2 * ((ids.scalar_v >> (ids.m - 1)) & 1)
+            + ((ids.scalar_u >> (ids.m - 1)) & 1)
+        )
+    %}
+    return quad_bit;
+}
+
+func test_quad_bit{range_check_ptr}() {
+    let u = 4194304;  // 1 << 22
+    let v = 8388608;  // 1 << 23
+
+    // 8 * 1 + 4 * 0 + 2 * 0 + 1 * 1
+    assert get_quad_bit(u, v, 23) = 9;
+
+    return ();
+}
+
+func main{range_check_ptr}() {
+    test_quad_bit();
+
+    return ();
+}

src/hint_processor/builtin_hint_processor/builtin_hint_processor_definition.rs

@@ -78,6 +78,8 @@ use felt::Felt252;
 #[cfg(feature = "skip_next_instruction_hint")]
 use crate::hint_processor::builtin_hint_processor::skip_next_instruction::skip_next_instruction;
 
+use super::secp::ec_utils::quad_bit;
+
 pub struct HintProcessorData {
     pub code: String,
     pub ap_tracking: ApTracking,
@@ -522,6 +524,7 @@ impl HintProcessor for BuiltinHintProcessor {
             hint_code::UINT256_MUL_DIV_MOD => {
                 uint256_mul_div_mod(vm, &hint_data.ids_data, &hint_data.ap_tracking)
             }
+            hint_code::QUAD_BIT => quad_bit(vm, &hint_data.ids_data, &hint_data.ap_tracking),
             #[cfg(feature = "skip_next_instruction_hint")]
             hint_code::SKIP_NEXT_INSTRUCTION => skip_next_instruction(vm),
             code => Err(HintError::UnknownHint(code.to_string())),

src/hint_processor/builtin_hint_processor/hint_code.rs

@@ -776,5 +776,12 @@ ids.root.d1 = root_split[1]
 ids.root.d2 = root_split[2]";
 pub const UINT384_SIGNED_NN: &str = "memory[ap] = 1 if 0 <= (ids.a.d2 % PRIME) < 2 ** 127 else 0";
 
+pub const QUAD_BIT: &str = r#"ids.quad_bit = (
+    8 * ((ids.scalar_v >> ids.m) & 1)
+    + 4 * ((ids.scalar_u >> ids.m) & 1)
+    + 2 * ((ids.scalar_v >> (ids.m - 1)) & 1)
+    + ((ids.scalar_u >> (ids.m - 1)) & 1)
+)"#;
+
 #[cfg(feature = "skip_next_instruction_hint")]
 pub const SKIP_NEXT_INSTRUCTION: &str = "skip_next_instruction()";

src/hint_processor/builtin_hint_processor/secp/ec_utils.rs

@@ -3,9 +3,13 @@ use crate::{
     hint_processor::{
         builtin_hint_processor::{
             hint_utils::{
-                get_integer_from_var_name, get_relocatable_from_var_name, insert_value_into_ap,
+                get_integer_from_var_name, get_relocatable_from_var_name,
+                insert_value_from_var_name, insert_value_into_ap,
+            },
+            secp::{
+                bigint_utils::BigInt3,
+                secp_utils::{pack, SECP_P},
             },
-            secp::secp_utils::pack,
         },
         hint_processor_definition::HintReference,
     },
@@ -18,9 +22,7 @@ use crate::{
 use felt::Felt252;
 use num_bigint::BigInt;
 use num_integer::Integer;
-use num_traits::{One, Zero};
-
-use super::{bigint_utils::BigInt3, secp_utils::SECP_P};
+use num_traits::{One, ToPrimitive, Zero};
 
 #[derive(Debug, PartialEq)]
 struct EcPoint<'a> {
@@ -272,6 +274,48 @@ pub fn ec_mul_inner(
     insert_value_into_ap(vm, scalar)
 }
 
+/*
+Implements hint:
+%{
+    ids.quad_bit = (
+        8 * ((ids.scalar_v >> ids.m) & 1)
+        + 4 * ((ids.scalar_u >> ids.m) & 1)
+        + 2 * ((ids.scalar_v >> (ids.m - 1)) & 1)
+        + ((ids.scalar_u >> (ids.m - 1)) & 1)
+    )
+%}
+*/
+pub fn quad_bit(
+    vm: &mut VirtualMachine,
+    ids_data: &HashMap<String, HintReference>,
+    ap_tracking: &ApTracking,
+) -> Result<(), HintError> {
+    let scalar_v_cow = get_integer_from_var_name("scalar_v", vm, ids_data, ap_tracking)?;
+    let scalar_u_cow = get_integer_from_var_name("scalar_u", vm, ids_data, ap_tracking)?;
+    let m_cow = get_integer_from_var_name("m", vm, ids_data, ap_tracking)?;
+
+    let scalar_v = scalar_v_cow.as_ref();
+    let scalar_u = scalar_u_cow.as_ref();
+    let Some(m) = m_cow.as_ref().to_u32() else {
+        return insert_value_from_var_name("quad_bit", 0, vm, ids_data, ap_tracking);
+    };
+
+    let one = &Felt252::one();
+
+    // 8 * ((ids.scalar_v >> ids.m) & 1)
+    let quad_bit_3 = ((scalar_v >> m) & one) << 3u32;
+    // 4 * ((ids.scalar_u >> ids.m) & 1)
+    let quad_bit_2 = ((scalar_u >> m) & one) << 2u32;
+    // 2 * ((ids.scalar_v >> (ids.m - 1)) & 1)
+    let quad_bit_1 = ((scalar_v >> (m - 1)) & one) << 1u32;
+    // 1 * ((ids.scalar_u >> (ids.m - 1)) & 1)
+    let quad_bit_0 = (scalar_u >> (m - 1)) & one;
+
+    let res = quad_bit_0 + quad_bit_1 + quad_bit_2 + quad_bit_3;
+
+    insert_value_from_var_name("quad_bit", res, vm, ids_data, ap_tracking)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -809,4 +853,27 @@ mod tests {
         let r = EcPoint::from_var_name("e", &vm, &ids_data, &ap_tracking);
         assert_matches!(r, Err(HintError::UnknownIdentifier(x)) if x == "e")
     }
+
+    #[test]
+    fn run_quad_bit_ok() {
+        let hint_code = "ids.quad_bit = (\n    8 * ((ids.scalar_v >> ids.m) & 1)\n    + 4 * ((ids.scalar_u >> ids.m) & 1)\n    + 2 * ((ids.scalar_v >> (ids.m - 1)) & 1)\n    + ((ids.scalar_u >> (ids.m - 1)) & 1)\n)";
+        let mut vm = vm_with_range_check!();
+
+        let scalar_u = 89712;
+        let scalar_v = 1478396;
+        let m = 4;
+        // Insert ids.scalar into memory
+        vm.segments = segments![((1, 0), scalar_u), ((1, 1), scalar_v), ((1, 2), m)];
+
+        // Initialize RunContext
+        run_context!(vm, 0, 4, 4);
+
+        let ids_data = ids_data!["scalar_u", "scalar_v", "m", "quad_bit"];
+
+        // Execute the hint
+        assert_matches!(run_hint!(vm, ids_data, hint_code), Ok(()));
+
+        // Check hint memory inserts
+        check_memory![vm.segments.memory, ((1, 3), 14)];
+    }
 }

src/tests/cairo_run_test.rs

@@ -1329,3 +1329,10 @@ fn cairo_run_div_mod_n() {
     let program_data = include_bytes!("../../cairo_programs/div_mod_n.json");
     run_program_simple(program_data.as_slice());
 }
+
+#[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+fn cairo_run_quad_bit() {
+    let program_data = include_bytes!("../../cairo_programs/quad_bit.json");
+    run_program_simple(program_data.as_slice());
+}