Implement Deg function

src/base.rs

@@ -1,3 +1,5 @@
+use std::cmp::min;
+
 // As defined in section 3.2
 pub struct PayloadId {
     pub source_block_number: u8,
@@ -23,3 +25,18 @@ pub struct EncodingPacket {
     pub symbol: Vec<u8>
 }
 
+// Deg[v] as defined in section 5.3.5.2
+pub fn deg(v: u32, lt_symbols: u32) -> u32 {
+    assert!(v < 1048576);
+    let f: [u32; 31] = [
+        0, 5243, 529531, 704294, 791675, 844104, 879057, 904023, 922747, 937311, 948962,
+        958494, 966438, 973160, 978921, 983914, 988283, 992138, 995565, 998631, 1001391,
+        1003887, 1006157, 1008229, 1010129, 1011876, 1013490, 1014983, 1016370, 1017662, 1048576];
+
+    for d in 1..f.len() {
+        if v < f[d] {
+            return min(d as u32, lt_symbols - 2);
+        }
+    }
+    panic!();
+}