Allow partial message reception

Handles cases where a read returns a partial packet by saving partial
pieces until a full packet is read.

2 files changed, 67 insertions, 20 deletions

diff --git a/src/vfs/ant_rx_chardev.c b/src/vfs/ant_rx_chardev.c
index 2af65a4..a596a88 100644
--- a/src/vfs/ant_rx_chardev.c
+++ b/src/vfs/ant_rx_chardev.c
@@ -232,14 +232,15 @@ int setFlowControl(ant_channel_info_t *pstChnlInfo, ANT_U8 ucFlowSetting)
 int readChannelMsg(ant_channel_type eChannel, ant_channel_info_t *pstChnlInfo)
 {
    int iRet = -1;
-   ANT_U8 aucRxBuffer[ANT_HCI_MAX_MSG_SIZE];
+   static ANT_U8 aucRxBuffer[ANT_HCI_MAX_MSG_SIZE];
+   static int iRxBufferLength = 0;
    int iRxLenRead;
    int iCurrentHciPacketOffset;
-   int iHciPacketSize;
+   int iHciDataSize;
    ANT_FUNC_START();
 
    // Keep trying to read while there is an error, and that error is EAGAIN
-   while (((iRxLenRead = read(pstChnlInfo->iFd, aucRxBuffer, sizeof(aucRxBuffer))) < 0)
+   while (((iRxLenRead = read(pstChnlInfo->iFd, &aucRxBuffer[iRxBufferLength], (sizeof(aucRxBuffer) - iRxBufferLength))) < 0)
                    && errno == EAGAIN)
       ;
 
@@ -263,6 +264,15 @@ int readChannelMsg(ant_channel_type eChannel, ant_channel_info_t *pstChnlInfo)
    } else {
       ANT_SERIAL(aucRxBuffer, iRxLenRead, 'R');
 
+      iRxLenRead += iRxBufferLength;   // add existing data on
+      
+      // if we didn't get a full packet, then just exit
+      if (iRxLenRead <= (aucRxBuffer[ANT_HCI_SIZE_OFFSET] + ANT_HCI_HEADER_SIZE + ANT_HCI_FOOTER_SIZE)) {
+         iRxBufferLength = iRxLenRead;
+         iRet = 0;
+         goto out;
+      }
+      
 #if ANT_HCI_OPCODE_SIZE == 1  // Check the different message types by opcode
       ANT_U8 opcode = aucRxBuffer[ANT_HCI_OPCODE_OFFSET];
 
@@ -290,8 +300,17 @@ int readChannelMsg(ant_channel_type eChannel, ant_channel_info_t *pstChnlInfo)
 
          while(iCurrentHciPacketOffset < iRxLenRead) {
 
-            iHciPacketSize = aucRxBuffer[iCurrentHciPacketOffset + ANT_HCI_SIZE_OFFSET];
+            // TODO Allow HCI Packet Size value to be larger than 1 byte
+            // This currently works as no size value is greater than 255, and little endian
+            iHciDataSize = aucRxBuffer[iCurrentHciPacketOffset + ANT_HCI_SIZE_OFFSET];
 
+            if ((iHciDataSize + ANT_HCI_HEADER_SIZE + ANT_HCI_FOOTER_SIZE + iCurrentHciPacketOffset) >= 
+                  iRxLenRead) {
+               // we don't have a whole packet
+               iRxBufferLength = iRxLenRead - iCurrentPacketOffset;
+               memcpy(aucRxBuffer, &aucRxBuffer[iCurrentHciPacketOffset], iRxBufferLength);
+               // the increment at the end should push us out of the while loop
+            } else
 #ifdef ANT_MESG_FLOW_CONTROL
             if (aucRxBuffer[iCurrentHciPacketOffset + ANT_HCI_DATA_OFFSET + ANT_MSG_ID_OFFSET] == 
                   ANT_MESG_FLOW_CONTROL) {
@@ -304,19 +323,16 @@ int readChannelMsg(ant_channel_type eChannel, ant_channel_info_t *pstChnlInfo)
 #endif // ANT_MESG_FLOW_CONTROL
             {
                if (pstChnlInfo->fnRxCallback != NULL) {
-                  // TODO Allow HCI Packet Size value to be larger than 1 byte
-                  // This currently works as no size value is greater than 255, and little endian
-
 
                   // Loop through read data until all HCI packets are written to callback
-                     pstChnlInfo->fnRxCallback(iHciPacketSize, \
+                     pstChnlInfo->fnRxCallback(iHciDataSize, \
                            &aucRxBuffer[iCurrentHciPacketOffset + ANT_HCI_DATA_OFFSET]);   
                } else {
                   ANT_WARN("%s rx callback is null", pstChnlInfo->pcDevicePath);
                }                  
             }
             
-            iCurrentHciPacketOffset = iCurrentHciPacketOffset + ANT_HCI_HEADER_SIZE + iHciPacketSize;               
+            iCurrentHciPacketOffset = iCurrentHciPacketOffset + ANT_HCI_HEADER_SIZE + ANT_HCI_FOOTER_SIZE + iHciDataSize;               
          }         
       }
 
diff --git a/src/vfs/prerelease/ant_driver_defines.h b/src/vfs/prerelease/ant_driver_defines.h
index 7b6b58b..f2e843b 100644
--- a/src/vfs/prerelease/ant_driver_defines.h
+++ b/src/vfs/prerelease/ant_driver_defines.h
@@ -29,39 +29,70 @@
 #ifndef __VFS_PRERELEASE_H
 #define __VFS_PRERELEASE_H
 
-#define ANT_CHIP_NAME                        "TTY"
-
-#define ANT_COMMANDS_DEVICE_NAME             "/dev/smd5"
-#define ANT_DATA_DEVICE_NAME                 "/dev/smd6"
-
-// Hard reset not supported, don't define ANT_IOCTL_RESET
-
 // -----------------------------------------
 // |         Header       | Data |  Footer  |
 // |----------------------|-----------------|
 // |Optional| Data | Opt. | ...  | Optional |
 // | Opcode | Size | Sync |      | Checksum |
+	
+// Data may include any number of ANT packets, with no sync byte or checksum.
+// A read from the driver may return any number of ANT HCI packets.
+
+
+// ---------------------- REQUIRED
+
+// Which chip is this library being built for:
+#define ANT_CHIP_NAME                        "TTY"
 
+// Set the file name the driver creates for the ANT device:
+//   If chip uses separate command and data paths:
+#define ANT_COMMANDS_DEVICE_NAME             "/dev/smd5"
+#define ANT_DATA_DEVICE_NAME                 "/dev/smd6"
+// OR
+//   If chip uses one path:
+// #define ANT_DEVICE_NAME                      "/dev/Z"
+
+	
+// Set to the number of bytes of header is for Opcode:
 #define ANT_HCI_OPCODE_SIZE                  0
+ 	
+// Set to the number of bytes of header is for Data Size:
 #define ANT_HCI_SIZE_SIZE                    1
-
+ 	
+// Set to the number of bytes of header is for Sync:
 #define ANT_HCI_SYNC_SIZE                    0
+ 	
+// Set to the number of bytes of footer is for Checksum:
 #define ANT_HCI_CHECKSUM_SIZE                0
+ 	
+// ---------------------- OPTIONAL
 
-#define ANT_MESG_FLOW_CONTROL                ((ANT_U8)0xC9)
+// If hard reset is supported, define ANT_IOCTL_RESET
+// #define ANT_IOCTL_RESET                      _IOW('U', 210, int)
+// #define ANT_IOCTL_RESET_PARAMETER            (0)
 
+// If the chip sends flow control messages:
+//  Define the Opcode for a Flow Control message:
+#define ANT_MESG_FLOW_CONTROL                ((ANT_U8)0xC9)
+// AND
+//   define the message content:
+//     That signals Flow Go:
 #define ANT_FLOW_GO                          ((ANT_U8)0x00)
+ 	
+//     That signals Flow Stop:
+#define ANT_FLOW_STOP                        ((ANT_U8)0x80)
 
-// ---------------------- Not chip specific
+// ---------------------- NOT CHIP SPECIFIC
+// These should not need to be modified, but should be verified they are correct
 
 #define ANT_HCI_HEADER_SIZE                  ((ANT_HCI_OPCODE_SIZE) + (ANT_HCI_SIZE_SIZE) + (ANT_HCI_SYNC_SIZE))
+#define ANT_HCI_FOOTER_SIZE                  (ANT_HCI_CHECKSUM_SIZE)
 
 #define ANT_HCI_OPCODE_OFFSET                0
 #define ANT_HCI_SIZE_OFFSET                  ((ANT_HCI_OPCODE_OFFSET) + (ANT_HCI_OPCODE_SIZE))
 #define ANT_HCI_SYNC_OFFSET                  ((ANT_HCI_SIZE_OFFSET) + (ANT_HCI_SIZE_SIZE))
 #define ANT_HCI_DATA_OFFSET                  (ANT_HCI_HEADER_SIZE)
 
-#define ANT_FLOW_STOP                        ((ANT_U8)0x80)
 #define ANT_FLOW_GO_WAIT_TIMEOUT_SEC         10
 
 #endif /* ifndef __VFS_PRERELEASE_H */