split bytes utils into unit

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/bytes.rs

@@ -0,0 +1,29 @@
+use crate::Result;
+
+#[inline]
+#[must_use]
+pub fn increment(old: Option<&[u8]>) -> [u8; 8] {
+	old.map(TryInto::try_into)
+		.map_or(0_u64, |val| val.map_or(0_u64, u64::from_be_bytes))
+		.wrapping_add(1)
+		.to_be_bytes()
+}
+
+/// Parses the big-endian bytes into an u64.
+#[inline]
+pub fn u64_from_bytes(bytes: &[u8]) -> Result<u64> {
+	let array: [u8; 8] = bytes.try_into()?;
+	Ok(u64_from_u8x8(array))
+}
+
+/// Parses the 8 big-endian bytes into an u64.
+#[inline]
+#[must_use]
+pub fn u64_from_u8(bytes: &[u8]) -> u64 {
+	let bytes: &[u8; 8] = bytes.try_into().expect("must slice at least 8 bytes");
+	u64_from_u8x8(*bytes)
+}
+
+#[inline]
+#[must_use]
+pub fn u64_from_u8x8(bytes: [u8; 8]) -> u64 { u64::from_be_bytes(bytes) }