Define names for twi errors

Rebase of arduino/Arduino#2152

Author: schonai

libraries/Wire/src/utility/twi.c

@@ -17,6 +17,7 @@
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
   Modified 2012 by Todd Krein ([email protected]) to implement repeated starts
+  Modified 2014 by Mickael Germain to define names for twi errors.
 */
 
 #include <math.h>
@@ -217,19 +218,19 @@ uint8_t twi_readFrom(uint8_t address, uint8_t* data, uint8_t length, uint8_t sen
  *          length: number of bytes in array
  *          wait: boolean indicating to wait for write or not
  *          sendStop: boolean indicating whether or not to send a stop at the end
- * Output   0 .. success
- *          1 .. length to long for buffer
- *          2 .. address send, NACK received
- *          3 .. data send, NACK received
- *          4 .. other twi error (lost bus arbitration, bus error, ..)
+ * Output   TWI_SUCCESS       .. success
+ *          TWI_DATA_TOO_LONG .. length to long for buffer
+ *          TWI_NACK_ON_ADDR  .. address send, NACK received
+ *          TWI_NACK_ON_DATA  .. data send, NACK received
+ *          TWI_OTHER_ERROR   .. other twi error (lost bus arbitration, bus error, ..)
  */
 uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait, uint8_t sendStop)
 {
   uint8_t i;
 
   // ensure data will fit into buffer
   if(TWI_BUFFER_LENGTH < length){
-    return 1;
+    return TWI_DATA_TOO_LONG;
   }
 
   // wait until twi is ready, become master transmitter
@@ -280,13 +281,13 @@ uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait
   }
 
   if (twi_error == 0xFF)
-    return 0;	// success
+    return TWI_SUCCESS;	// success
   else if (twi_error == TW_MT_SLA_NACK)
-    return 2;	// error: address send, nack received
+    return TWI_NACK_ON_ADDR;	// error: address send, nack received
   else if (twi_error == TW_MT_DATA_NACK)
-    return 3;	// error: data send, nack received
+    return TWI_NACK_ON_DATA;	// error: data send, nack received
   else
-    return 4;	// other twi error
+    return TWI_OTHER_ERROR;	// other twi error
 }
 
 /* 
@@ -295,22 +296,22 @@ uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait
  *          must be called in slave tx event callback
  * Input    data: pointer to byte array
  *          length: number of bytes in array
- * Output   1 length too long for buffer
- *          2 not slave transmitter
- *          0 ok
+ * Output   TWI_DATA_TOO_LONG .. length too long for buffer
+ *          TWI_NOT_SLAVE_TX  .. not slave transmitter
+ *          0                 .. ok
  */
 uint8_t twi_transmit(const uint8_t* data, uint8_t length)
 {
   uint8_t i;
 
   // ensure data will fit into buffer
   if(TWI_BUFFER_LENGTH < (twi_txBufferLength+length)){
-    return 1;
+    return TWI_DATA_TOO_LONG;
   }
 
   // ensure we are currently a slave transmitter
   if(TWI_STX != twi_state){
-    return 2;
+    return TWI_NOT_SLAVE_TX;
   }
 
   // set length and copy data into tx buffer

libraries/Wire/src/utility/twi.h

@@ -37,7 +37,14 @@
   #define TWI_MTX   2
   #define TWI_SRX   3
   #define TWI_STX   4
-  
+
+  #define TWI_SUCCESS       0
+  #define TWI_DATA_TOO_LONG 1
+  #define TWI_NACK_ON_ADDR  2
+  #define TWI_NOT_SLAVE_TX  2
+  #define TWI_NACK_ON_DATA  3
+  #define TWI_OTHER_ERROR   4
+
   void twi_init(void);
   void twi_disable(void);
   void twi_setAddress(uint8_t);