openpgp: Move byte order conversion functions.

1 files changed, 38 insertions, 0 deletions

diff --git a/openpgp/src/utils.rs b/openpgp/src/utils.rs
new file mode 100644
index 00000000..5abc968b
--- /dev/null
+++ b/openpgp/src/utils.rs
@@ -0,0 +1,38 @@
+//! Utility functions that don't fit anywhere else.
+
+pub fn read_be_u64(b: &[u8]) -> u64 {
+    assert_eq!(b.len(), 8);
+    ((b[0] as u64) << 56) as u64
+        | ((b[1] as u64) << 48)
+        | ((b[2] as u64) << 40)
+        | ((b[3] as u64) << 32)
+        | ((b[4] as u64) << 24)
+        | ((b[5] as u64) << 16)
+        | ((b[6] as u64) <<  8)
+        | ((b[7] as u64) <<  0)
+}
+
+pub fn write_be_u64(b: &mut [u8], n: u64) {
+    assert_eq!(b.len(), 8);
+    b[0] = (n >> 56) as u8;
+    b[1] = (n >> 48) as u8;
+    b[2] = (n >> 40) as u8;
+    b[3] = (n >> 32) as u8;
+    b[4] = (n >> 24) as u8;
+    b[5] = (n >> 16) as u8;
+    b[6] = (n >>  8) as u8;
+    b[7] = (n >>  0) as u8;
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    quickcheck! {
+        fn be_u64_roundtrip(n: u64) -> bool {
+            let mut b = [0; 8];
+            write_be_u64(&mut b, n);
+            n == read_be_u64(&b)
+        }
+    }
+}