--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/docs/CRC.c	Sun Nov 19 18:10:23 2017 +1030
@@ -0,0 +1,53 @@
+INT16U cal_crc_half(INT8U far *pin, INT8U len)
+{
+
+	INT16U crc;
+
+	INT8U da;
+	INT8U far *ptr;
+	INT8U bCRCHign;
+    INT8U bCRCLow;
+
+	INT16U crc_ta[16]=
+	{ 
+		0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
+
+		0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef
+	};
+	ptr=pin;
+	crc=0;
+	
+	while(len--!=0) 
+	{
+		da=((INT8U)(crc>>8))>>4; 
+
+		crc<<=4;
+
+		crc^=crc_ta[da^(*ptr>>4)]; 
+
+		da=((INT8U)(crc>>8))>>4; 
+
+		crc<<=4;
+
+		crc^=crc_ta[da^(*ptr&0x0f)]; 
+
+		ptr++;
+	}
+	bCRCLow = crc;
+
+    bCRCHign= (INT8U)(crc>>8);
+
+	if(bCRCLow==0x28||bCRCLow==0x0d||bCRCLow==0x0a)
+
+    {
+    	bCRCLow++;
+    }
+    if(bCRCHign==0x28||bCRCHign==0x0d||bCRCHign==0x0a)
+
+    {
+		bCRCHign++;
+    }
+    crc = ((INT16U)bCRCHign)<<8;
+    crc += bCRCLow;
+	return(crc);
+}