Import of the watch repository from Pebble

platform/snowy/boot/src/util/crc32.h

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+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+//! \file
+//! Calculate the CRC-32 checksum of data.
+//!
+//! The checksum is the standard CRC-32 used by zlib, PNG and others.
+//! The model parameters for the algorithm, as described in A Painless Guide to
+//! CRC Error Detection Algorithms (http://www.zlib.net/crc_v3.txt), are:
+//!   Name: "CRC-32"
+//!   Width: 32
+//!   Poly: 04C11DB7
+//!   Init: FFFFFFFF
+//!   RefIn: True
+//!   RefOut: True
+//!   XorOut: FFFFFFFF
+//!   Check: CBF43926
+
+#include <stdint.h>
+#include <string.h>
+
+//! Update a running CRC-32 checksum with the bytes of data and return the
+//! updated CRC-32. If data is NULL, the function returns the required initial
+//! value for the CRC.
+//!
+//! This function is drop-in compatible with zlib's crc32 function.
+//!
+//! \par Usage
+//! \code
+//!   uint32_t crc = crc32(0, NULL, 0);
+//!   while (read_buffer(data, length)) {
+//!     crc = crc32(crc, data, length);
+//!   }
+//! \endcode
+uint32_t crc32(uint32_t crc, const void * restrict data, size_t length);
+
+//! The initial CRC register value for a standard CRC-32 checksum.
+//!
+//! It is the same value as is returned by the `crc32` function when data is
+//! NULL.
+//!
+//! \code
+//!   assert(CRC32_INIT == crc32(0, NULL, 0));
+//! \endcode
+#define CRC32_INIT (0)
+
+//! The residue constant of the CRC-32 algorithm.
+//!
+//! If the CRC-32 value of a message is appended (little-endian) onto the
+//! end of the message, the CRC-32 of the concatenated message and CRC will be
+//! equal to CRC32_RESIDUE if the message has not been corrupted in transit.
+#define CRC32_RESIDUE (0x2144DF1C)