Add CRC16 (CCITT).

crc16_ccitt.c

@@ -0,0 +1,58 @@
+/*
+ * This file is part of the Aaru Data Preservation Suite.
+ * Copyright (c) 2019-2021 Natalia Portillo.
+ *
+ * This library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of the
+ * License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "crc16_ccitt.h"
+
+#include "library.h"
+
+crc16_ccitt_ctx* crc16_ccitt_init(void)
+{
+    crc16_ccitt_ctx* ctx = (crc16_ccitt_ctx*)malloc(sizeof(crc16_ccitt_ctx));
+
+    if(!ctx) return NULL;
+
+    ctx->crc = 0x0000;
+
+    return ctx;
+}
+
+int crc16_ccitt_update(crc16_ccitt_ctx* ctx, const uint8_t* data, uint32_t len)
+{
+    if(!ctx || !data) return -1;
+
+    for(uint32_t i = 0; i < len; i++) ctx->crc = crc16_ccitt_table[(ctx->crc >> 8) ^ data[i]] ^ (ctx->crc << 8);
+
+    return 0;
+}
+
+int crc16_ccitt_final(crc16_ccitt_ctx* ctx, uint16_t* crc)
+{
+    if(!ctx) return -1;
+
+    *crc = ~ctx->crc;
+
+    return 0;
+}
+
+void crc16_ccitt_free(crc16_ccitt_ctx* ctx)
+{
+    if(ctx) free(ctx);
+}