--- libaitpelco/src/aitpelco.c	2010/03/12 14:57:18	1.1.1.1.2.2
+++ libaitpelco/src/aitpelco.c	2010/03/17 13:34:34	1.1.1.1.2.4
@@ -3,7 +3,7 @@
 *  by Michael Pounov <misho@openbsd-bg.org>
 *
 * $Author: misho $
-* $Id: aitpelco.c,v 1.1.1.1.2.2 2010/03/12 14:57:18 misho Exp $
+* $Id: aitpelco.c,v 1.1.1.1.2.4 2010/03/17 13:34:34 misho Exp $
 *
 *************************************************************************/
 #include "global.h"
@@ -60,7 +60,7 @@ inline void *pelcoOpen(u_char pelcoVer, u_char camNo)
 		case 'D':
 		case 'd':
 			if (camNo < FIRST_CAM_D) {
-				pelcoSetErr(ENOEXEC, "Error:: unsupported camera number %d!\n", camNo);
+				pelcoSetErr(ENOEXEC, "unsupported camera number %d!\n", camNo);
 				return NULL;
 			}
 
@@ -92,7 +92,7 @@ inline void *pelcoOpen(u_char pelcoVer, u_char camNo)
 			p = pp;
 			break;
 		default:
-			pelcoSetErr(ENOEXEC, "Error:: unsupported Pelco protocol version!\n");
+			pelcoSetErr(ENOEXEC, "unsupported Pelco protocol version!\n");
 	}
 
 	return p;
@@ -122,7 +122,7 @@ inline void *pelcoLoad(u_char *buffer)
 	switch (pelco_GetVersion(buffer)) {
 		case 'd':
 			if (pelco_GetCamNo(buffer) < FIRST_CAM_D) {
-				pelcoSetErr(ENOEXEC, "Error:: unsupported camera number %d!\n", 
+				pelcoSetErr(ENOEXEC, "unsupported camera number %d!\n", 
 						pelco_GetCamNo(buffer));
 				return NULL;
 			}
@@ -147,7 +147,7 @@ inline void *pelcoLoad(u_char *buffer)
 			p = pp;
 			break;
 		default:
-			pelcoSetErr(ENOEXEC, "Error:: unsupported Pelco protocol version!\n");
+			pelcoSetErr(ENOEXEC, "unsupported Pelco protocol version!\n");
 	}
 
 	return p;
@@ -168,14 +168,14 @@ inline u_char pelcoAddCmdData(void * __restrict p, u_c
 	u_char *ptr = p;
 
 	if (!p) {
-		pelcoSetErr(EINVAL, "Error:: invalid argument!\n");
+		pelcoSetErr(EINVAL, "invalid argument!\n");
 		return 0xFF;
 	}
 
 	switch (ptr[0]) {
 		case VER_D_SYNC:
 			if (ptr[1] < FIRST_CAM_D) {
-				pelcoSetErr(ENOEXEC, "Error:: unsupported camera number %d!\n", ptr[1]);
+				pelcoSetErr(ENOEXEC, "unsupported camera number %d!\n", ptr[1]);
 				return 0xFF;
 			}
 
@@ -187,7 +187,7 @@ inline u_char pelcoAddCmdData(void * __restrict p, u_c
 			break;
 		case VER_P_STX:
 			if (VER_P_ETX != ptr[6]) {
-				pelcoSetErr(ENOEXEC, "Error:: Broken Pelco P packet!\n");
+				pelcoSetErr(ENOEXEC, "Broken Pelco P packet!\n");
 				return 0xFF;
 			}
 
@@ -198,7 +198,7 @@ inline u_char pelcoAddCmdData(void * __restrict p, u_c
 			pp->p_crc = crcPelco('p', p);
 			break;
 		default:
-			pelcoSetErr(ENOEXEC, "Error:: Invalid protocol!\n");
+			pelcoSetErr(ENOEXEC, "Invalid protocol!\n");
 			return 0xFF;
 	}
 
@@ -215,4 +215,50 @@ inline u_char pelcoAddCmdData(void * __restrict p, u_c
 inline u_char pelcoGetCmdData(void * __restrict p, u_char * __restrict cmd, u_char * __restrict data)
 {
 	return pelco_GetCamCmdData(p, NULL, cmd, data);
+}
+
+/*
+ * pelcoChkSum() Check ot Correct check sum in packet
+ * @p = Input Packet structure
+ * @correct = Calculate new check sum if incorrect !=0, if ==0 only check
+ * return: 0xFF - bad packet, 1 invalid check sum, 0 check sum is correct.
+ */
+inline u_char pelcoChkSum(void * __restrict p, u_char correct)
+{
+	u_char sum, *ptr = p;
+	pelco_d_t *pd = (pelco_d_t *) p;
+	pelco_p_t *pp = (pelco_p_t *) p;
+
+	if (!p) {
+		pelcoSetErr(EINVAL, "invalid argument!\n");
+		return 0xFF;
+	}
+
+	switch (ptr[0]) {
+		case VER_D_SYNC:
+			if (ptr[1] < FIRST_CAM_D) {
+				pelcoSetErr(ENOEXEC, "unsupported camera number %d!\n", ptr[1]);
+				return 0xFF;
+			}
+
+			sum = crcPelco('d', p);
+			if (correct)
+				pd->d_crc = sum;
+			break;
+		case VER_P_STX:
+			if (VER_P_ETX != ptr[6]) {
+				pelcoSetErr(ENOEXEC, "Broken Pelco P packet!\n");
+				return 0xFF;
+			}
+
+			sum = crcPelco('p', p);
+			if (correct)
+				pp->p_crc = sum;
+			break;
+		default:
+			pelcoSetErr(ENOEXEC, "Invalid protocol!\n");
+			return 0xFF;
+	}
+
+	return sum;
 }