Add wrapper around error detection functions (#23)

Author: jbangelo

build.rs

@@ -26,6 +26,7 @@ fn main() {
         .header(format!("{}/include/swiftnav/ionosphere.h", dst.display()))
         .header(format!("{}/include/swiftnav/troposphere.h", dst.display()))
         .header(format!("{}/include/swiftnav/ephemeris.h", dst.display()))
+        .header(format!("{}/include/swiftnav/edc.h", dst.display()))
         // Tell cargo to invalidate the built crate whenever any of the
         // included header files changed.
         .parse_callbacks(Box::new(bindgen::CargoCallbacks))
@@ -80,6 +81,7 @@ fn main() {
         .whitelist_function("decode_ephemeris")
         .whitelist_function("decode_bds_d1_ephemeris")
         .whitelist_function("decode_gal_ephemeris")
+        .whitelist_function("crc24q")
         // Finish the builder and generate the bindings.
         .generate()
         // Unwrap the Result and panic on failure.

src/edc.rs

@@ -0,0 +1,36 @@
+use crate::c_bindings;
+
+pub fn compute_crc24q(buf: &[u8], initial_value: u32) -> u32 {
+    unsafe { c_bindings::crc24q(buf.as_ptr(), buf.len() as u32, initial_value) }
+}
+
+#[cfg(test)]
+mod tests {
+    const TEST_DATA: &[u8] = "123456789".as_bytes();
+
+    #[test]
+    fn crc24q() {
+        let crc = super::compute_crc24q(&TEST_DATA[0..0], 0);
+        assert!(
+            crc == 0,
+            "CRC of empty buffer with starting value 0 should be 0, not {}",
+            crc
+        );
+
+        let crc = super::compute_crc24q(&TEST_DATA[0..0], 22);
+        assert!(
+            crc == 22,
+            "CRC of empty buffer with starting value 22 should be 22, not {}",
+            crc
+        );
+
+        /* Test value taken from python crcmod package tests, see:
+         * http://crcmod.sourceforge.net/crcmod.predefined.html */
+        let crc = super::compute_crc24q(TEST_DATA, 0xB704CE);
+        assert!(
+            crc == 0x21CF02,
+            "CRC of \"123456789\" with init value 0xB704CE should be {}, not 0x%06X",
+            crc
+        );
+    }
+}

src/lib.rs

@@ -16,6 +16,7 @@
 
 mod c_bindings;
 pub mod coords;
+pub mod edc;
 pub mod ephemeris;
 pub mod ionosphere;
 pub mod signal;