From 34733eae8843b6d2cd89c5fcd7d485e25a5ea0ea Mon Sep 17 00:00:00 2001
From: Leo Lara <leo@leolara.me>
Date: Thu, 13 Apr 2023 15:13:33 +0700
Subject: [PATCH] Add fibonacci example

---
 examples/fibonacci.rs | 148 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 examples/fibonacci.rs

diff --git a/examples/fibonacci.rs b/examples/fibonacci.rs
new file mode 100644
index 0000000..56b0607
--- /dev/null
+++ b/examples/fibonacci.rs
@@ -0,0 +1,148 @@
+use chiquito::{
+    ast::ToField,
+    backend::halo2::{chiquito2Halo2, ChiquitoHalo2},
+    compiler::{
+        cell_manager::SingleRowCellManager, step_selector::SimpleStepSelectorBuilder, Compiler,
+    },
+    dsl::circuit,
+};
+use halo2_proofs::{
+    circuit::SimpleFloorPlanner,
+    dev::MockProver,
+    halo2curves::{bn256::Fr, FieldExt},
+    plonk::ConstraintSystem,
+};
+
+fn fibo_circuit<F: FieldExt>() -> chiquito::ir::Circuit<F, (), (u64, u64)> {
+    let fibo = circuit::<F, (), (u64, u64), _>("fibonacci", |ctx| {
+        use chiquito::dsl::cb::*;
+
+        let a = ctx.forward("a");
+        let b = ctx.forward("b");
+
+        let fibo_step = ctx.step_type("fibo step");
+        let fibo_last_step = ctx.step_type("last step");
+
+        ctx.pragma_first_step(fibo_step);
+        ctx.pragma_last_step(fibo_last_step);
+
+        ctx.step_type_def(fibo_step, |ctx| {
+            let c = ctx.internal("c");
+
+            ctx.constr("a + b == c", eq(a + b, c));
+            ctx.transition("b == a.next", eq(b, a.next()));
+            ctx.transition("c == b.next", eq(c, b.next()));
+
+            ctx.wg(move |ctx, (a_value, b_value)| {
+                println!("fib line wg: {} {} {}", a_value, b_value, a_value + b_value);
+                ctx.assign(a, a_value.field());
+                ctx.assign(b, b_value.field());
+                ctx.assign(c, (a_value + b_value).field());
+            });
+        });
+
+        ctx.step_type_def(fibo_last_step, |ctx| {
+            let c = ctx.internal("c");
+
+            ctx.constr("a + b == c", eq(a + b, c));
+
+            ctx.wg(move |ctx, (a_value, b_value)| {
+                println!(
+                    "fib last line wg: {} {} {}",
+                    a_value,
+                    b_value,
+                    a_value + b_value
+                );
+                ctx.assign(a, a_value.field());
+                ctx.assign(b, b_value.field());
+                ctx.assign(c, (a_value + b_value).field());
+            });
+        });
+
+        ctx.trace(move |ctx, _| {
+            ctx.add(&fibo_step, (1, 1));
+            let mut a = 1;
+            let mut b = 2;
+
+            for i in 1..10 {
+                ctx.add(&fibo_step, (a, b));
+
+                let prev_a = a;
+                a = b;
+                b = prev_a + b;
+            }
+
+            ctx.add(&fibo_last_step, (a, b));
+        })
+    });
+
+    //println!("{:#?}", fibo);
+
+    let compiler = Compiler::new(SingleRowCellManager {}, SimpleStepSelectorBuilder {});
+
+    let compiled = compiler.compile(&fibo);
+
+    //println!("{:#?}", compiled);
+
+    compiled
+}
+
+fn main() {
+    let circuit = FiboCircuit {};
+
+    let prover = MockProver::<Fr>::run(7, &circuit, Vec::new()).unwrap();
+
+    let result = prover.verify_par();
+
+    println!("{:#?}", result);
+
+    if let Err(failures) = &result {
+        for failure in failures.iter() {
+            println!("{}", failure);
+        }
+    }
+}
+
+// *** Halo2 boilerplate ***
+
+#[derive(Clone)]
+struct FiboConfig<F: FieldExt> {
+    compiled: ChiquitoHalo2<F, (), (u64, u64)>,
+}
+
+impl<F: FieldExt> FiboConfig<F> {
+    fn new(meta: &mut ConstraintSystem<F>) -> FiboConfig<F> {
+        let mut compiled = chiquito2Halo2(fibo_circuit::<F>());
+
+        compiled.configure(meta);
+
+        FiboConfig { compiled }
+    }
+}
+
+#[derive(Default)]
+struct FiboCircuit {}
+
+impl<F: FieldExt> halo2_proofs::plonk::Circuit<F> for FiboCircuit {
+    type Config = FiboConfig<F>;
+
+    type FloorPlanner = SimpleFloorPlanner;
+
+    fn without_witnesses(&self) -> Self {
+        Self::default()
+    }
+
+    fn configure(meta: &mut halo2_proofs::plonk::ConstraintSystem<F>) -> Self::Config {
+        FiboConfig::<F>::new(meta)
+    }
+
+    fn synthesize(
+        &self,
+        config: Self::Config,
+        mut layouter: impl halo2_proofs::circuit::Layouter<F>,
+    ) -> Result<(), halo2_proofs::plonk::Error> {
+        config.compiled.synthesize(&mut layouter, ());
+
+        Ok(())
+    }
+}