Add crc16 builtin

source/crc.c

@@ -78,4 +78,25 @@ void CRC_ProcessByte(unsigned short *crcvalue, byte data)
 unsigned short CRC_Value(unsigned short crcvalue)
 {
 	return crcvalue ^ CRC_XOR_VALUE;
+}
+
+//
+// taken from darkplaces -- just a shortcut for initialization for
+// use with string-hashing (just progs, likely). -- cypress (07 jan 2024)
+//
+
+unsigned short CRC_Block(const unsigned char *data, size_t size)
+{
+	unsigned short crc = CRC_INIT_VALUE;
+	while (size--)
+		crc = (crc << 8) ^ crctable[(crc >> 8) ^ (*data++)];
+	return crc ^ CRC_XOR_VALUE;
+}
+
+unsigned short CRC_Block_CaseInsensitive(const unsigned char *data, size_t size)
+{
+	unsigned short crc = CRC_INIT_VALUE;
+	while (size--)
+		crc = (crc << 8) ^ crctable[(crc >> 8) ^ (tolower(*data++))];
+	return crc ^ CRC_XOR_VALUE;
 }

source/crc.h

@@ -22,3 +22,6 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 void CRC_Init(unsigned short *crcvalue);
 void CRC_ProcessByte(unsigned short *crcvalue, byte data);
 unsigned short CRC_Value(unsigned short crcvalue);
+
+unsigned short CRC_Block(const unsigned char *data, size_t size);
+unsigned short CRC_Block_CaseInsensitive(const unsigned char *data, size_t size);

source/pr_cmds.c

@@ -1356,6 +1356,21 @@ void PF_strtolower(void)
 	G_INT(OFS_RETURN) = pr_string_temp - pr_strings;
 }
 
+/*
+=================
+PF_crc16
+
+float crc16 (float, string)
+=================
+*/
+void PF_crc16(void)
+{
+	int insens = G_FLOAT(OFS_PARM0);
+	char *s = G_STRING(OFS_PARM1);
+
+	G_FLOAT(OFS_RETURN) = (unsigned short) ((insens ? CRC_Block_CaseInsensitive : CRC_Block) ((unsigned char *) s, strlen(s)));
+}
+
 /*
 =================
 PF_substring
@@ -3964,7 +3979,7 @@ PF_Fixme,
 PF_Fixme, 
 PF_Fixme, 
 PF_Fixme, 
-PF_Fixme, 
+PF_crc16, 
 PF_Fixme, 
 PF_Fixme, 
 PF_Fixme,