From fcef5a57f5f38bd39e8ed5989c58ad8fd6b8c50f Mon Sep 17 00:00:00 2001
From: wborgeaud <williamborgeaud@gmail.com>
Date: Mon, 7 Feb 2022 10:25:01 +0100
Subject: [PATCH] Fibonacci recursive constraints

---
 starky/src/fibonacci_stark.rs | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/starky/src/fibonacci_stark.rs b/starky/src/fibonacci_stark.rs
index c77775e8..18bc46b5 100644
--- a/starky/src/fibonacci_stark.rs
+++ b/starky/src/fibonacci_stark.rs
@@ -79,7 +79,25 @@ impl<F: RichField + Extendable<D>, const D: usize> Stark<F, D> for FibonacciStar
         vars: StarkEvaluationTargets<D, { Self::COLUMNS }, { Self::PUBLIC_INPUTS }>,
         yield_constr: &mut RecursiveConstraintConsumer<F, D>,
     ) {
-        todo!()
+        // Check public inputs.
+        let pis_constraints = [
+            builder.sub_extension(vars.local_values[0], vars.public_inputs[Self::PI_INDEX_X0]),
+            builder.sub_extension(vars.local_values[1], vars.public_inputs[Self::PI_INDEX_X1]),
+            builder.sub_extension(vars.local_values[1], vars.public_inputs[Self::PI_INDEX_RES]),
+        ];
+        yield_constr.constraint_first_row(builder, pis_constraints[0]);
+        yield_constr.constraint_first_row(builder, pis_constraints[1]);
+        yield_constr.constraint_last_row(builder, pis_constraints[2]);
+
+        // x0 <- x1
+        let first_col_constraint = builder.sub_extension(vars.next_values[0], vars.local_values[1]);
+        yield_constr.constraint(builder, first_col_constraint);
+        // x1 <- x0 + x1
+        let second_col_constraint = {
+            let tmp = builder.sub_extension(vars.next_values[1], vars.local_values[0]);
+            builder.sub_extension(tmp, vars.local_values[1])
+        };
+        yield_constr.constraint(builder, second_col_constraint);
     }
 
     fn constraint_degree(&self) -> usize {