Add SHA-1 checksum calculation support

include/sha1.h

@@ -0,0 +1,53 @@
+/*
+ * Public domain or MIT-licensed SHA-1 implementation for libaaruformat.
+ *
+ * Based on a clean-room implementation referencing the FIPS PUB 180-1 specification.
+ *
+ * This code is released into the public domain. If that is not recognized
+ * in your jurisdiction, you may treat it under the terms of the MIT license:
+ *
+ * MIT License
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef LIBAARUFORMAT_SHA1_H
+#define LIBAARUFORMAT_SHA1_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#ifndef SHA1_DIGEST_LENGTH
+#define SHA1_DIGEST_LENGTH 20
+#endif
+
+    typedef struct
+    {
+        uint32_t state[5]; /* A,B,C,D,E */
+        uint64_t count;    /* Bits processed */
+        uint8_t  buffer[64];
+    } sha1_ctx;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* LIBAARUFORMAT_SHA1_H */