Greatly simplify crc32 c-ffi

zlstringham · Apr 25, 2022 · af0b7bd · af0b7bd
1 parent ab54a3e
commit af0b7bd
Showing 1 changed file with 15 additions and 118 deletions.
diff --git a/c-ffi/src/crc32.rs b/c-ffi/src/crc32.rs
@@ -3,134 +3,31 @@ use core::slice;
 use byond_crc32::Crc32;
 use libc::size_t;
 
-/// Represents a CRC-32/BYOND checksum computation.
-#[repr(C)]
-pub struct Crc32Struct {
-    _private: [u8; 0],
-}
-
-/// Creates and initializes a new CRC-32/BYOND checksum.
-///
-/// # Safety
-///
-/// The pointer returned must be freed with `crc32_destroy`.
-#[no_mangle]
-pub extern "C" fn crc32_create() -> *mut Crc32Struct {
-    Box::into_raw(Box::new(Crc32::new())) as *mut Crc32Struct
-}
-
-/// Creates and initializes an in-progress CRC-32/BYOND checksum.
-///
-/// This initializer accepts a starting checksum and the length of data used to
-/// calculate the checksum up to this point. The length is used in the
-/// calculation for `crc32_combine`.
-///
-/// # Safety
-///
-/// The pointer returned must be freed with `crc32_destroy`.
-#[no_mangle]
-pub extern "C" fn crc32_create_with_initial(crc: u32, len: size_t) -> *mut Crc32Struct {
-    Box::into_raw(Box::new(Crc32::new_with_initial(crc, len as u64))) as *mut Crc32Struct
-}
+pub const DEFAULT_CRC32: u32 = 0xffffffff;
 
 /// Creates a CRC-32/BYOND checksum as the combination of two component
 /// checksums.
-///
-/// # Safety
-///
-/// The pointer returned must be freed with `crc32_destroy`. The two component
-/// checksums are not freed by this function and must still be freed with
-/// `crc32_destroy`. The component pointers should point to valid crc32 structs.
-#[no_mangle]
-pub unsafe extern "C" fn crc32_combine(
-    crc_a_ptr: *const Crc32Struct,
-    crc_b_ptr: *const Crc32Struct,
-) -> *mut Crc32Struct {
-    match (
-        (crc_a_ptr as *const Crc32).as_ref(),
-        (crc_b_ptr as *const Crc32).as_ref(),
-    ) {
-        (Some(a), Some(b)) => Box::into_raw(Box::new(Crc32::combine(a, b))) as *mut Crc32Struct,
-        (_, _) => std::ptr::null_mut(),
-    }
-}
-
-/// Free the heap memory from a CRC-32/BYOND checksum.
-///
-/// # Safety
-///
-/// The pointer should point to a valid crc32 struct.
-#[no_mangle]
-pub unsafe extern "C" fn crc32_destroy(crc_ptr: *mut Crc32Struct) {
-    if !crc_ptr.is_null() {
-        let _ = Box::from_raw(crc_ptr as *mut Crc32);
-    }
-}
-
-/// Gets the 32-bit value of a CRC-32/BYOND checksum.
-///
-/// # Safety
-///
-/// The pointer should point to a valid crc32 struct.
-#[no_mangle]
-pub unsafe extern "C" fn crc32_as_u32(crc_ptr: *const Crc32Struct) -> u32 {
-    if let Some(crc) = (crc_ptr as *const Crc32).as_ref() {
-        return crc.as_u32();
-    }
-    0xffffffff
-}
-
-/// Returns whether or not the CRC-32/BYOND checksum has ingested no data.
-///
-/// # Safety
-///
-/// The pointer should point to a valid crc32 struct.
 #[no_mangle]
-pub unsafe extern "C" fn crc32_is_empty(crc_ptr: *const Crc32Struct) -> bool {
-    if let Some(crc) = (crc_ptr as *const Crc32).as_ref() {
-        return crc.is_empty();
-    }
-    true
-}
-
-/// Returns the length of data ingested by the CRC-32/BYOND checksum.
-///
-/// # Safety
-///
-/// The pointer should point to a valid crc32 struct.
-#[no_mangle]
-pub unsafe extern "C" fn crc32_len(crc_ptr: *const Crc32Struct) -> u64 {
-    if let Some(crc) = (crc_ptr as *const Crc32).as_ref() {
-        return crc.len();
-    }
-    0
-}
-
-/// Resets a CRC-32/BYOND checksum to the default state.
-///
-/// This can be useful for reusing a single checksum to hash multiple
-/// data streams, rather than allocating separate checksums for each stream.
-///
-/// # Safety
-///
-/// The pointer should point to a valid crc32 struct.
-#[no_mangle]
-pub unsafe extern "C" fn crc32_reset(crc_ptr: *mut Crc32Struct) {
-    if let Some(crc) = (crc_ptr as *mut Crc32).as_mut() {
-        crc.reset();
-    }
+pub extern "C" fn crc32_combine(crc_a: u32, crc_b: u32, crc_b_len: u64) -> u32 {
+    Crc32::combine(
+        &Crc32::new_with_initial(crc_a, 0),
+        &Crc32::new_with_initial(crc_b, crc_b_len),
+    )
+    .as_u32()
 }
 
 /// Updates a CRC-32/BYOND checksum with some data.
 ///
 /// # Safety
 ///
-/// The pointer should point to a valid crc32 struct, and len should not
-/// exceed the length of data.
+/// The given len should not exceed the length of data.
 #[no_mangle]
-pub unsafe extern "C" fn crc32_update(crc_ptr: *mut Crc32Struct, data: *const u8, len: size_t) {
-    match (data.is_null(), (crc_ptr as *mut Crc32).as_mut()) {
-        (false, Some(crc)) => crc.update(slice::from_raw_parts(data, len)),
-        (_, _) => (),
+pub unsafe extern "C" fn crc32_update(crc: u32, data: *const u8, len: size_t) -> u32 {
+    if data.is_null() {
+        crc
+    } else {
+        let mut crc32 = Crc32::new_with_initial(crc, 0);
+        crc32.update(slice::from_raw_parts(data, len));
+        crc32.as_u32()
     }
 }