From eefd214309fc3f8a0b5415184e833948bd5bbb1e Mon Sep 17 00:00:00 2001
From: N8BWert <n8.wert.b@gmail.com>
Date: Sat, 5 Oct 2024 18:26:01 -0400
Subject: [PATCH] generate Packable implementations for primitive numbers +
 default to big-endian packing

---
 ncomm-utils/Cargo.toml     |   3 +-
 ncomm-utils/src/packing.rs | 103 +++++++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/ncomm-utils/Cargo.toml b/ncomm-utils/Cargo.toml
index 13b4f5b..da4d08b 100644
--- a/ncomm-utils/Cargo.toml
+++ b/ncomm-utils/Cargo.toml
@@ -16,4 +16,5 @@ repository.workspace = true
 default = ["std"]
 nostd = []
 alloc = []
-std = []
\ No newline at end of file
+std = []
+little-endian = []
\ No newline at end of file
diff --git a/ncomm-utils/src/packing.rs b/ncomm-utils/src/packing.rs
index 0db37f3..12babf2 100644
--- a/ncomm-utils/src/packing.rs
+++ b/ncomm-utils/src/packing.rs
@@ -28,3 +28,106 @@ pub trait Packable: Sized {
     /// Unpack a given piece of data from an array of bytes
     fn unpack(data: &[u8]) -> Result<Self, PackingError>;
 }
+
+#[cfg(feature = "little-endian")]
+macro_rules! packable_primitive {
+    ($primitive_name: ident, $length: literal) => {
+        impl Packable for $primitive_name {
+            fn len() -> usize {
+                $length as usize
+            }
+
+            fn pack(self, buffer: &mut [u8]) -> Result<(), PackingError> {
+                if buffer.len() < Self::len() {
+                    return Err(PackingError::InvalidBufferSize);
+                }
+
+                buffer[..Self::len()].copy_from_slice(&self.to_le_bytes()[..]);
+                Ok(())
+            }
+
+            fn unpack(data: &[u8]) -> Result<Self, PackingError> {
+                if data.len() < Self::len() {
+                    return Err(PackingError::InvalidBufferSize);
+                }
+
+                Ok(Self::from_le_bytes(data[..Self::len()].try_into().unwrap()))
+            }
+        }
+    };
+}
+
+#[cfg(not(feature = "little-endian"))]
+macro_rules! packable_primitive {
+    ($primitive_name: ident, $length: literal) => {
+        impl Packable for $primitive_name {
+            fn len() -> usize {
+                $length as usize
+            }
+
+            fn pack(self, buffer: &mut [u8]) -> Result<(), PackingError> {
+                if buffer.len() < Self::len() {
+                    return Err(PackingError::InvalidBufferSize);
+                }
+
+                buffer[..Self::len()].copy_from_slice(&self.to_be_bytes()[..]);
+                Ok(())
+            }
+
+            fn unpack(data: &[u8]) -> Result<Self, PackingError> {
+                if data.len() < Self::len() {
+                    return Err(PackingError::InvalidBufferSize);
+                }
+
+                Ok(Self::from_be_bytes(data[..Self::len()].try_into().unwrap()))
+            }
+        }
+    };
+}
+
+packable_primitive!(u8, 1);
+packable_primitive!(u16, 2);
+packable_primitive!(u32, 4);
+packable_primitive!(u64, 8);
+packable_primitive!(u128, 16);
+packable_primitive!(usize, 8);
+packable_primitive!(i8, 1);
+packable_primitive!(i16, 2);
+packable_primitive!(i32, 4);
+packable_primitive!(i64, 8);
+packable_primitive!(i128, 16);
+packable_primitive!(isize, 8);
+packable_primitive!(f32, 4);
+packable_primitive!(f64, 8);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    macro_rules! test_primitive_packing {
+        ($primitive: ident, $buffer_length: literal, $value: literal, $test_name: ident) => {
+            #[test]
+            fn $test_name() {
+                let mut buffer = [0u8; $buffer_length as usize];
+                assert!($value.pack(&mut buffer).is_ok());
+                println!("buffer: {:?}", buffer);
+                assert_eq!($value, $primitive::unpack(&buffer).unwrap());
+            }
+        };
+    }
+
+    test_primitive_packing!(u8, 1, 129u8, test_u8_packing);
+    test_primitive_packing!(u16, 2, 129u16, test_u16_packing);
+    test_primitive_packing!(u32, 4, 129u32, test_u32_packing);
+    test_primitive_packing!(u64, 8, 129u64, test_u64_packing);
+    test_primitive_packing!(u128, 16, 129u128, test_u128_packing);
+    test_primitive_packing!(usize, 16, 129usize, test_usize_packing);
+    test_primitive_packing!(i8, 1, 15i8, test_i8_packing);
+    test_primitive_packing!(i16, 2, 129i16, test_i16_packing);
+    test_primitive_packing!(i32, 4, 129i32, test_i32_packing);
+    test_primitive_packing!(i64, 8, 129i64, test_i64_packing);
+    test_primitive_packing!(i128, 16, 129i128, test_i128_packing);
+    test_primitive_packing!(isize, 16, 129isize, test_isize_packing);
+    test_primitive_packing!(f32, 4, 2.01f32, test_f32_packing);
+    test_primitive_packing!(f64, 8, 2.01f64, test_f64_packing);
+}
\ No newline at end of file