From 96117e05c387c930c9619e3ae5c0ad0b4da196d2 Mon Sep 17 00:00:00 2001
From: Jonathan McCrohan <jmccrohan@gmail.com>
Date: Sun, 20 May 2012 19:15:37 +0100
Subject: modbuslog: Add support for signed registers

---
 src/modbuslog.c | 87 +++++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 63 insertions(+), 24 deletions(-)

(limited to 'src')

diff --git a/src/modbuslog.c b/src/modbuslog.c
index 3f9b658..da03a11 100644
--- a/src/modbuslog.c
+++ b/src/modbuslog.c
@@ -197,6 +197,10 @@ int main(int argc, char *argv[]) {
 			config_setting_lookup_int(register_element, "numbytes",
 					&numbytes);
 
+			int signedvalue;
+			config_setting_lookup_int(register_element, "signedvalue",
+					&signedvalue);
+
 			const char *intervalunit;
 			config_setting_lookup_string(register_element, "intervalunit",
 					&intervalunit);
@@ -340,7 +344,7 @@ int main(int argc, char *argv[]) {
 				syslog(LOG_DEBUG, "opening file for append: [%s]",
 						log_filename);
 
-				int32_t registervalue = 0;
+				uint32_t registervalue;
 
 				int p;
 
@@ -353,20 +357,32 @@ int main(int argc, char *argv[]) {
 					//registervalue += tab_reg[i] + tab_reg[i + 1];
 				}
 
+				// initialise register value
+				// need to check if 2s complement
+				if (signedvalue && (byte[0]>>7)){
+					registervalue = 0xffffffff;
+				} else{
+					registervalue = 0;
+				}
+
 				// bitshifting magic
 				switch (numbytes) {
 				case 1:
-					registervalue = (startbyte % 2 == 0) ? byte[0] : byte[1];
+					registervalue <<= 8;
+					registervalue |= ((startbyte % 2 == 0) ? byte[0] : byte[1]);
 					break;
 				case 2:
-					registervalue = ((byte[0]) << 8) + byte[1];
+					registervalue <<= 16;
+					registervalue |= (((byte[0]) << 8) + byte[1]);
 					break;
 				case 4:
-					registervalue = ((byte[0]) << 24) + ((byte[1]) << 16)
-							+ ((byte[2]) << 8) + byte[3];
+					registervalue <<= 24;
+					registervalue |= (((byte[0]) << 24) + ((byte[1]) << 16)
+							+ ((byte[2]) << 8) + byte[3]);
 					break;
 				default:
-					registervalue = ((byte[0]) << 8) + byte[1];
+					registervalue <<= 16;
+					registervalue |= (((byte[0]) << 8) + byte[1]);
 					break;
 				}
 
@@ -409,24 +425,47 @@ int main(int argc, char *argv[]) {
 				fprintf(intervalfile, "%d", intervalid);
 				fclose(intervalfile);
 
-				fprintf(
-						filehandle,
-						"%i|%04i%02i%02i|%02i%02i%02i|%04i%02i%02i|%02i%02i%02i|%i|%i|%i\n",
-						intervalid, utc.tm_year + 1900, utc.tm_mon + 1,
-						utc.tm_mday, utc.tm_hour, utc.tm_min, utc.tm_sec,
-						lc.tm_year + 1900, lc.tm_mon + 1, lc.tm_mday,
-						lc.tm_hour, lc.tm_min, lc.tm_sec, slaveid, startbyte,
-						registervalue);
-				fclose(filehandle);
-
-				syslog(
-						LOG_DEBUG,
-						"[%i|%04i%02i%02i|%02i%02i%02i|%04i%02i%02i|%02i%02i%02i|%i|%i|%i]\n",
-						intervalid, utc.tm_year + 1900, utc.tm_mon + 1,
-						utc.tm_mday, utc.tm_hour, utc.tm_min, utc.tm_sec,
-						lc.tm_year + 1900, lc.tm_mon + 1, lc.tm_mday,
-						lc.tm_hour, lc.tm_min, lc.tm_sec, slaveid, startbyte,
-						registervalue);
+				if (signedvalue){
+
+					fprintf(
+							filehandle,
+							"%i|%04i%02i%02i|%02i%02i%02i|%04i%02i%02i|%02i%02i%02i|%i|%i|%i\n",
+							intervalid, utc.tm_year + 1900, utc.tm_mon + 1,
+							utc.tm_mday, utc.tm_hour, utc.tm_min, utc.tm_sec,
+							lc.tm_year + 1900, lc.tm_mon + 1, lc.tm_mday,
+							lc.tm_hour, lc.tm_min, lc.tm_sec, slaveid, startbyte,
+							registervalue);
+					fclose(filehandle);
+
+					syslog(
+							LOG_DEBUG,
+							"[%i|%04i%02i%02i|%02i%02i%02i|%04i%02i%02i|%02i%02i%02i|%i|%i|%i]\n",
+							intervalid, utc.tm_year + 1900, utc.tm_mon + 1,
+							utc.tm_mday, utc.tm_hour, utc.tm_min, utc.tm_sec,
+							lc.tm_year + 1900, lc.tm_mon + 1, lc.tm_mday,
+							lc.tm_hour, lc.tm_min, lc.tm_sec, slaveid, startbyte,
+							registervalue);
+				} else{
+					fprintf(
+							filehandle,
+							"%i|%04i%02i%02i|%02i%02i%02i|%04i%02i%02i|%02i%02i%02i|%i|%i|%u\n",
+							intervalid, utc.tm_year + 1900, utc.tm_mon + 1,
+							utc.tm_mday, utc.tm_hour, utc.tm_min, utc.tm_sec,
+							lc.tm_year + 1900, lc.tm_mon + 1, lc.tm_mday,
+							lc.tm_hour, lc.tm_min, lc.tm_sec, slaveid, startbyte,
+							registervalue);
+					fclose(filehandle);
+
+					syslog(
+							LOG_DEBUG,
+							"[%i|%04i%02i%02i|%02i%02i%02i|%04i%02i%02i|%02i%02i%02i|%i|%i|%u]\n",
+							intervalid, utc.tm_year + 1900, utc.tm_mon + 1,
+							utc.tm_mday, utc.tm_hour, utc.tm_min, utc.tm_sec,
+							lc.tm_year + 1900, lc.tm_mon + 1, lc.tm_mday,
+							lc.tm_hour, lc.tm_min, lc.tm_sec, slaveid, startbyte,
+							registervalue);
+				}
+
 
 				modbus_close(ctx);
 				modbus_free(ctx);
-- 
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