[#1793] Implement EC ADD circuit + witness generation

Squash

msm/Cargo.toml

@@ -21,12 +21,14 @@ ark-bn254.workspace = true
 ark-serialize.workspace = true
 o1-utils.workspace = true
 kimchi.workspace = true
+itertools.workspace = true
 poly-commitment.workspace = true
 groupmap.workspace = true
 mina-curves.workspace = true
 mina-poseidon.workspace = true
 num-bigint.workspace = true
 num-integer.workspace = true
+num-traits.workspace = true
 rmp-serde.workspace = true
 serde_json.workspace = true
 serde.workspace = true

msm/src/fec/columns.rs

@@ -0,0 +1,4 @@
+use crate::N_LIMBS;
+
+/// Number of columns in the FEC circuits.
+pub const FEC_N_COLUMNS: usize = 34 * N_LIMBS + 42 * N_LIMBS; // 42 LIMBS is for debugging

msm/src/fec/constraint.rs

@@ -0,0 +1,54 @@
+use crate::{columns::Column, expr::E, fec::interpreter::FECInterpreterEnv};
+use ark_ff::PrimeField;
+use kimchi::circuits::{
+    expr::{ConstantExpr, ConstantTerm, Expr, ExprInner, Variable},
+    gate::CurrOrNext,
+};
+
+/// Contains constraints for just one row.
+pub struct ConstraintBuilderEnv<F> {
+    pub constraints: Vec<E<F>>,
+}
+
+impl<F: PrimeField> FECInterpreterEnv<F> for ConstraintBuilderEnv<F> {
+    type Variable = E<F>;
+
+    fn empty() -> Self {
+        ConstraintBuilderEnv {
+            constraints: vec![],
+        }
+    }
+
+    fn assert_zero(&mut self, cst: Self::Variable) {
+        self.constraints.push(cst)
+    }
+
+    fn copy(&mut self, x: &Self::Variable, position: Column) -> Self::Variable {
+        let y = Expr::Atom(ExprInner::Cell(Variable {
+            col: position,
+            row: CurrOrNext::Curr,
+        }));
+        self.constraints.push(y.clone() - x.clone());
+        y
+    }
+
+    fn constant(value: F) -> Self::Variable {
+        let cst_expr_inner = ConstantExpr::from(ConstantTerm::Literal(value));
+        Expr::Atom(ExprInner::Constant(cst_expr_inner))
+    }
+
+    fn read_column(&self, ix: Column) -> Self::Variable {
+        Expr::Atom(ExprInner::Cell(Variable {
+            col: ix,
+            row: CurrOrNext::Curr,
+        }))
+    }
+
+    fn range_check_abs1(&mut self, _value: &Self::Variable) {
+        // FIXME unimplemented
+    }
+
+    fn range_check_15bit(&mut self, _value: &Self::Variable) {
+        // FIXME unimplemented
+    }
+}