Split off the CRC code to its own module.

src/utils/CMakeLists.txt

@@ -17,6 +17,7 @@
 
 add_library(utils OBJECT
     cJSON.c
+    crc.c
     fifo.c
     fifo8.c
     ini.c

src/utils/crc.c

@@ -0,0 +1,77 @@
+/*
+ * 86Box    A hypervisor and IBM PC system emulator that specializes in
+ *          running old operating systems and software designed for IBM
+ *          PC systems and compatibles from 1981 through fairly recent
+ *          system designs based on the PCI bus.
+ *
+ *          This file is part of the 86Box distribution.
+ *
+ *          CRC implementation.
+ *
+ * Authors: Miran Grca, <mgrca8@gmail.com>
+ *
+ *          Copyright 2016-2025 Miran Grca.
+ */
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <assert.h>
+#include <wchar.h>
+#define HAVE_STDARG_H
+#include <86box/86box.h>
+#include <86box/timer.h>
+#include <86box/dma.h>
+#include <86box/nvr.h>
+#include <86box/random.h>
+#include <86box/plat.h>
+#include <86box/ui.h>
+#include <86box/crc.h>
+
+#ifdef ENABLE_CRC_LOG
+int d86f_do_log = ENABLE_CRC_LOG;
+
+static void
+crc_log(const char *fmt, ...)
+{
+    va_list ap;
+
+    if (crc_do_log) {
+        va_start(ap, fmt);
+        pclog_ex(fmt, ap);
+        va_end(ap);
+    }
+}
+#else
+#    define crc_log(fmt, ...)
+#endif
+
+void
+crc16_setup(uint16_t *crc_table, uint16_t poly)
+{
+    int      c = 256;
+    int      bc;
+    uint16_t temp;
+
+    while (c--) {
+        temp = c << 8;
+        bc   = 8;
+
+        while (bc--) {
+            if (temp & 0x8000)
+                temp = (temp << 1) ^ poly;
+            else
+                temp <<= 1;
+
+            crc_table[c] = temp;
+        }
+    }
+}
+
+void
+crc16_calc(uint16_t *crc_table, uint8_t byte, crc_t *crc_var)
+{
+    crc_var->word = (crc_var->word << 8) ^
+                    crc_table[(crc_var->word >> 8) ^ byte];
+}