make crc code cleaner

src/durandal/crc.rs

@@ -1,11 +1,13 @@
+fn crc_accum(a: u32) -> u32
+{
+    if a & 1 == 1 {0xedb88320 ^ a >> 1}
+    else                       {a >> 1}
+}
+
 fn crc_init() -> [u32; 256]
 {
    let mut t = [0; 256];
-   for n in 0..256
-   {
-      t[n] = (0..8).fold(n as u32, |a, _|
-         {if a & 1 == 1 {0xedb88320 ^ a >> 1} else {a >> 1}});
-   }
+   for n in 0..256 {t[n] = (0..8).fold(n as u32, |a, _| crc_accum(a))}
    t
 }