main: add quick bench

Signed-off-by: Ignacio Hagopian <jsign.uy@gmail.com>

src/main.zig

@@ -1,5 +1,37 @@
 const std = @import("std");
 const testing = std.testing;
+const parameters = @import("parameters.zig");
+const poseidon = @import("poseidon.zig");
+const Fr = @import("bn254/fr.zig");
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+
+    var bn254_params = try parameters.get_babyjubjub_parameters(gpa.allocator());
+    defer bn254_params.deinit();
+
+    const widths = [_]usize{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
+
+    inline for (widths) |w| {
+        var instance = poseidon.Poseidon(Fr, w + 1).init(bn254_params);
+        var buf: [32]u8 = undefined;
+
+        var frs: [w]Fr.NonMontgomeryDomainFieldElement = undefined;
+        for (0..w, 0..) |v, i| {
+            std.mem.writeIntLittle(u256, &buf, v);
+            var nonMont: Fr.NonMontgomeryDomainFieldElement = undefined;
+            Fr.fromBytes(&nonMont, buf);
+            Fr.toMontgomery(&frs[i], nonMont);
+        }
+
+        const now = std.time.microTimestamp();
+        const n: i64 = 10_000;
+        for (0..n) |_| {
+            _ = instance.hash(frs);
+        }
+        std.debug.print("Poseidon(width={}) took {}µs\n", .{ w, @divTrunc(std.time.microTimestamp() - now, n) });
+    }
+}
 
 test "tests" {
     std.testing.log_level = .debug;