members/libpt-bintols/src/join.rs

@@ -0,0 +1,50 @@
+//! # Join bits and bytes into numbers
+//!
+//! Sometimes you have a `[u8]` that is the representation of a larger unsigned integer, such as
+//! [u128]. This module helps you join them together.
+
+use anyhow::anyhow;
+use libpt_log::trace;
+
+/// Join a [Vec] of [u8]s into an unsigned integer
+///
+/// Say you have the array `[0b00000110, 0b10110101]` and want to use it as a [u32].
+/// This function sets it together to a integer type of your choosing:
+/// 1717 (binary: `00000000 00000000 00000110 10110101`).
+///
+/// If the array is not long enough, the number will be padded with null bytes.
+///
+/// # Examples
+///
+/// ```
+/// # use libpt_bintols::join::*;
+///
+/// let x: [u8; 2] = [0b00000110, 0b10110101];
+///
+/// assert_eq!(array_to_unsigned::<u32>(&x).unwrap(), 1717);
+/// ```
+pub fn array_to_unsigned<T>(parts: &[u8]) -> anyhow::Result<T>
+where
+    u128: std::convert::From<T>,
+    T: std::str::FromStr,
+    T: std::convert::TryFrom<u128>,
+    <T as std::str::FromStr>::Err: std::fmt::Debug,
+    <T as std::str::FromStr>::Err: std::error::Error,
+    <T as std::convert::TryFrom<u128>>::Error: std::error::Error,
+    <T as std::convert::TryFrom<u128>>::Error: std::marker::Send,
+    <T as std::convert::TryFrom<u128>>::Error: std::marker::Sync,
+    <T as std::convert::TryFrom<u128>>::Error: 'static,
+{
+    trace!("amount of parts: {}", parts.len());
+    if parts.len() > (u128::BITS / 8) as usize {
+        return Err(anyhow!(
+            "the list is too long to fit into the specified integer type: {}",
+            std::any::type_name::<T>()
+        ));
+    }
+    let mut ri: u128 = 0;
+    for (i, e) in parts.iter().rev().enumerate() {
+        ri += (*e as u128) * 256u128.pow(i as u32);
+    }
+    T::try_from(ri).map_err(anyhow::Error::from)
+}

members/libpt-bintols/src/lib.rs

@@ -25,4 +25,5 @@ pub const YOBI: u128 = 2u128.pow(80);
 // use libpt_core;
 pub mod datalayout;
 pub mod display;
+pub mod join;
 pub mod split;

members/libpt-bintols/tests/join.rs

@@ -0,0 +1,55 @@
+use libpt_bintols::join::*;
+
+#[test]
+fn join_u128() {
+    let correct = [
+        16,
+        255,
+        256,
+        0,
+        u128::MAX,
+        u64::MAX as u128,
+        u64::MAX as u128 + 1,
+    ];
+    let source = [
+        vec![16],
+        vec![255],
+        vec![1, 0],
+        vec![0],
+        vec![
+            255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+        ],
+        vec![255, 255, 255, 255, 255, 255, 255, 255],
+        vec![1, 0, 0, 0, 0, 0, 0, 0, 0],
+    ];
+    for (i, n) in source.iter().enumerate() {
+        assert_eq!(array_to_unsigned::<u128>(n).unwrap(), correct[i]);
+    }
+}
+
+#[test]
+fn join_u64() {
+    let correct = [
+        16,
+        255,
+        256,
+        0,
+        u64::MAX,
+        u32::MAX as u64,
+        0b1_00000001,
+        0b10011011_10110101_11110000_00110011,
+    ];
+    let source = [
+        vec![16],
+        vec![255],
+        vec![1, 0],
+        vec![0],
+        vec![255, 255, 255, 255, 255, 255, 255, 255],
+        vec![255, 255, 255, 255],
+        vec![1, 1],
+        vec![0b10011011, 0b10110101, 0b11110000, 0b00110011],
+    ];
+    for (i, n) in source.iter().enumerate() {
+        assert_eq!(array_to_unsigned::<u64>(n).unwrap(), correct[i]);
+    }
+}