From 9f9bca0f197ee7920dc4daa81cbb4c6698e660a7 Mon Sep 17 00:00:00 2001
From: Cristian Maglie <c.maglie@bug.st>
Date: Wed, 5 Jun 2013 11:50:33 +0200
Subject: Bridge protocol frame lenght is now a 16-bit field. Added more
 efficient Bridge.trasnfer() methods.

---
 libraries/Bridge/Bridge.cpp | 46 ++++++++++++++++++++++++++++++++-------------
 libraries/Bridge/Bridge.h   | 16 ++++++++++++++--
 2 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/libraries/Bridge/Bridge.cpp b/libraries/Bridge/Bridge.cpp
index f13f909..2aafc52 100644
--- a/libraries/Bridge/Bridge.cpp
+++ b/libraries/Bridge/Bridge.cpp
@@ -168,21 +168,34 @@ bool BridgeClass::crcCheck(uint16_t _CRC) {
   return CRC == _CRC;
 }
 
-uint8_t BridgeClass::transfer(const uint8_t *buff, uint8_t len, 
-                              uint8_t *rxbuff, uint8_t rxlen) 
+uint8_t BridgeClass::transfer(const uint8_t *buff1, uint16_t len1,
+                 const uint8_t *buff2, uint16_t len2,
+                 const uint8_t *buff3, uint16_t len3,
+                 uint8_t *rxbuff, uint16_t rxlen)
 {
+  uint16_t len = len1 + len2 + len3;
   for ( ; ; delay(100), dropAll() /* Delay for retransmission */) {
     // Send packet
     crcReset();
-    write((char)0xFF);              // Start of packet (0xFF)
+    write((char)0xFF);                // Start of packet (0xFF)
     crcUpdate(0xFF);
-    write((char)index);             // Message index
+    write((char)index);               // Message index
     crcUpdate(index);
-    write((char)len);               // Message length
-    crcUpdate(len);
-    for (uint8_t i=0; i<len; i++) { // Payload
-      write((char)buff[i]);
-      crcUpdate(buff[i]);
+    write((char)((len >> 8) & 0xFF)); // Message length (hi)
+    crcUpdate((len >> 8) & 0xFF);
+    write((char)(len & 0xFF));        // Message length (lo)
+    crcUpdate(len & 0xFF);
+    for (uint8_t i=0; i<len1; i++) {  // Payload
+      write((char)buff1[i]);
+      crcUpdate(buff1[i]);
+    }
+    for (uint8_t i=0; i<len2; i++) {  // Payload
+      write((char)buff2[i]);
+      crcUpdate(buff2[i]);
+    }
+    for (uint8_t i=0; i<len3; i++) {  // Payload
+      write((char)buff3[i]);
+      crcUpdate(buff3[i]);
     }
     crcWrite();                     // CRC
   
@@ -198,13 +211,20 @@ uint8_t BridgeClass::transfer(const uint8_t *buff, uint8_t len,
     crcUpdate(index);
     
     // Recv len
-    uint8_t l = timedRead(5);
-    if (l < 0)
+    int lh = timedRead(5);
+    if (lh < 0)
+      continue;
+    crcUpdate(lh);
+    int ll = timedRead(5);
+    if (ll < 0)
       continue;
-    crcUpdate(l);
+    crcUpdate(ll);
+    uint16_t l = lh;
+    l <<= 8;
+    l += ll;
 
     // Recv data
-    for (uint8_t i=0; i<l; i++) {
+    for (uint16_t i=0; i<l; i++) {
       int c = timedRead(5);
       if (c < 0)
         continue;
diff --git a/libraries/Bridge/Bridge.h b/libraries/Bridge/Bridge.h
index ff5cd5f..c7b5361 100644
--- a/libraries/Bridge/Bridge.h
+++ b/libraries/Bridge/Bridge.h
@@ -65,8 +65,20 @@ public:
   void flush() { stream.flush(); }
 
   // Trasnfer a frame (with error correction and response)
-  uint8_t transfer(const uint8_t *buff, uint8_t len, 
-                   uint8_t *rxbuff=NULL, uint8_t rxlen=0);
+  uint8_t transfer(const uint8_t *buff1, uint16_t len1,
+                   const uint8_t *buff2, uint16_t len2,
+                   const uint8_t *buff3, uint16_t len3,
+                   uint8_t *rxbuff, uint16_t rxlen);
+  // multiple inline versions of the same function to allow efficient frame concatenation
+  uint8_t transfer(const uint8_t *buff1, uint16_t len1)
+  { transfer(buff1, len1, NULL, 0); }
+  uint8_t transfer(const uint8_t *buff1, uint16_t len1,
+                   uint8_t *rxbuff, uint16_t rxlen)
+  { transfer(buff1, len1, NULL, 0, rxbuff, rxlen); }
+  uint8_t transfer(const uint8_t *buff1, uint16_t len1,
+                   const uint8_t *buff2, uint16_t len2,
+                   uint8_t *rxbuff, uint16_t rxlen)
+  { transfer(buff1, len1, buff2, len2, NULL, 0, rxbuff, rxlen); }
 private:
   uint8_t index;
   int timedRead(unsigned int timeout);
-- 
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