migrate over endian, serial and error placeholder libs

example/halo2/Cargo.lock

@@ -425,6 +425,7 @@ dependencies = [
  "ff",
  "halo2",
  "halo2_gadgets",
+ "hex",
  "pasta_curves",
  "rand",
 ]
@@ -644,6 +645,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "hex"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
+
 [[package]]
 name = "ident_case"
 version = "1.0.1"

example/halo2/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2021"
 rand = "0.8.4"
 ff = "0.11.0"
 pasta_curves = "0.2.1"
+hex = "0.4.3"
 
 [dependencies.halo2]
 version = "=0.1.0-beta.1"

example/halo2/src/lib.rs

@@ -1,4 +1,7 @@
 pub mod constants;
 pub mod crypto;
+pub mod endian;
+pub mod error;
 pub mod proof;
+pub mod serial;
 pub mod spec;