Correct missing #, Also add CRC calculate function and correct one of

the overloaded methods
peterj43 · Jul 12, 2021 · 96feec0 · 96feec0
1 parent a49cc13
commit 96feec0
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Showing 2 changed files with 39 additions and 10 deletions.
diff --git a/src/SDI12.cpp b/src/SDI12.cpp
@@ -848,7 +848,8 @@ void SDI12::sendResponse(FlashString resp) {
   }
   setState(SDI12_LISTENING);      // return to listening state
 }
-ifdef USE_CRC
+
+#ifdef USE_CRC
 #define POLY 0xa001
 String SDI12::addCRCResponse(String &resp) {
   char  crcStr[3] = {0};
@@ -857,12 +858,12 @@ String SDI12::addCRCResponse(String &resp) {
   for(int i = 0; i < resp.length(); i++) {
     crc ^= (uint16_t)resp[i];     //Set the CRC equal to the exclusive OR of the character and itself
     for (int j = 0; j <  8; j++){ //count = 1 to 8
-      if (crc & 0x0001){         //if the least significant bit of the CRC is one
-         crc >>= 1;              //right shift the CRC one bit
-         crc ^= POLY;            //set CRC equal to the exclusive OR of POLY and itself
+      if (crc & 0x0001){          //if the least significant bit of the CRC is one
+        crc >>= 1;                //right shift the CRC one bit
+        crc ^= POLY;              //set CRC equal to the exclusive OR of POLY and itself
       }
       else {
-         crc >>=  1;             //right shift the CRC one bit
+        crc >>=  1;               //right shift the CRC one bit
       }
     }
   }
@@ -873,15 +874,15 @@ String SDI12::addCRCResponse(String &resp) {
 }
 
 char * SDI12::addCRCResponse(char *resp) {
-  char *crcStr  = "\0";
-  uint16_t crc   = 0;
+  char *crcStr[3] = {0};
+  uint16_t crc    = 0;
 
   for(int i = 0; i < strlen(resp); i++) {
     crc ^= (uint16_t)resp[i];     //Set the CRC equal to the exclusive OR of the character and itself
     for (int j = 0; j <  8; j++){ //count = 1 to 8
-      if (crc & 0x0001){         //if the least significant bit of the CRC is one
-         crc >>= 1;              //right shift the CRC one bit
-         crc ^= POLY;            //set CRC equal to the exclusive OR of POLY and itself
+      if (crc & 0x0001){          //if the least significant bit of the CRC is one
+        crc >>= 1;                //right shift the CRC one bit
+        crc ^= POLY;              //set CRC equal to the exclusive OR of POLY and itself
       }
       else {
         crc >>=  1;             //right shift the CRC one bit
@@ -923,6 +924,29 @@ String SDI12::addCRCResponse(FlashString resp) {
   crcStr[2] = (char)( 0x0040 |  (crc & 0x003F));
   return (outResp  + String(crcStr[0]) + String(crcStr[1]) + String(crcStr[2]));
 }
+
+String SDI12::calculateCRC(String &resp){
+   char  crcStr[3] = {0};
+   uint16_t crc    = 0;
+
+   for(int i = 0; i < resp.length(); i++) {
+      crc ^= (uint16_t)resp[i];     //Set the CRC equal to the exclusive OR of the character and itself
+      for (int j = 0; j <  8; j++){ //count = 1 to 8
+         if (crc & 0x0001){         //if the least significant bit of the CRC is one
+            crc >>= 1;              //right shift the CRC one bit
+            crc ^= POLY;            //set CRC equal to the exclusive OR of POLY and itself
+         }
+         else {
+            crc >>=  1;             //right shift the CRC one bit
+         }
+      }
+   }
+   crcStr[0] = (char)( 0x0040 |  (crc >> 12));
+   crcStr[1] = (char)( 0x0040 | ((crc >> 6) & 0x003F));
+   crcStr[2] = (char)( 0x0040 |  (crc & 0x003F));
+   return (String(crcStr[0]) + String(crcStr[1]) + String(crcStr[2]));
+}
+
 #endif //USE_CRC
 
 

diff --git a/src/SDI12.h b/src/SDI12.h
@@ -51,6 +51,9 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 
 typedef const __FlashStringHelper *FlashString;
 
+
+//#define USE_CRC
+
 #define NO_IGNORE_CHAR '\x01' // a char not found in a valid ASCII numeric field
 #define SDI12_BUFFER_SIZE  81 // <address> is a single character
                               // +<values> has a maximum value of 75 characters.
@@ -65,6 +68,7 @@ enum LookaheadMode
   SKIP_NONE,      // Nothing is skipped, and the stream is not touched unless the first waiting character is valid.
   SKIP_WHITESPACE // Only tabs, spaces, line feeds & carriage returns are skipped.
 };
+
 #define READTIME sdi12timer.SDI12TimerRead()
 #else
 #define READTIME TCNTX
@@ -134,6 +138,7 @@ class SDI12 : public Stream
   String addCRCResponse(String &resp);     // Add CRC to the  resp  string (for slave use)
   char * addCRCResponse( char *resp);      // Add CRC to the  resp  string (for slave use)
   String addCRCResponse(FlashString resp); // Add CRC to the  resp  string (for slave use)
+  String calculateCRC(String &resp);       // Calculate the CRC for a response
  #endif
 
   int available();            // returns the number of bytes available in buffer