Added fp_to_bytes

evm-tests/ethcore-builtin/Cargo.toml

@@ -23,6 +23,7 @@ hex-literal = "0.4"
 c-kzg = "1.0"
 derive_more = "0.99"
 hex = "0.4.3"
+blst = "0.3.13"
 
 [dev-dependencies]
 maplit = "1.0.2"

evm-tests/ethcore-builtin/src/bls.rs

@@ -0,0 +1,31 @@
+#![allow(dead_code)]
+use blst::{blst_bendian_from_fp, blst_fp};
+
+/// Number of bits used in the BLS12-381 curve finite field elements.
+const NBITS: usize = 256;
+/// Finite field element input length.
+const FP_LENGTH: usize = 48;
+/// Finite field element padded input length.
+const PADDED_FP_LENGTH: usize = 64;
+/// Quadratic extension of finite field element input length.
+const PADDED_FP2_LENGTH: usize = 128;
+/// Input elements padding length.
+const PADDING_LENGTH: usize = 16;
+/// Scalar length.
+const SCALAR_LENGTH: usize = 32;
+// Big-endian non-Montgomery form.
+const MODULUS_REPR: [u8; 48] = [
+	0x1a, 0x01, 0x11, 0xea, 0x39, 0x7f, 0xe6, 0x9a, 0x4b, 0x1b, 0xa7, 0xb6, 0x43, 0x4b, 0xac, 0xd7,
+	0x64, 0x77, 0x4b, 0x84, 0xf3, 0x85, 0x12, 0xbf, 0x67, 0x30, 0xd2, 0xa0, 0xf6, 0xb0, 0xf6, 0x24,
+	0x1e, 0xab, 0xff, 0xfe, 0xb1, 0x53, 0xff, 0xff, 0xb9, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xaa, 0xab,
+];
+
+/// BLS Encodes a single finite field element into byte slice with padding.
+pub fn fp_to_bytes(out: &mut [u8], input: *const blst_fp) {
+	if out.len() != PADDED_FP_LENGTH {
+		return;
+	}
+	let (padding, rest) = out.split_at_mut(PADDING_LENGTH);
+	padding.fill(0);
+	unsafe { blst_bendian_from_fp(rest.as_mut_ptr(), input) };
+}

evm-tests/ethcore-builtin/src/lib.rs

@@ -18,6 +18,7 @@
 
 #![warn(missing_docs)]
 
+mod bls;
 mod kzg;
 
 use std::{