From 88bc2aa5e7e7c3870700a40d78829b51d3ae3754 Mon Sep 17 00:00:00 2001
From: "R. Steve McKown" <rsmckown@gmail.com>
Date: Wed, 7 Apr 2010 19:16:46 -0600
Subject: [PATCH] USCI fixes.

* Watch out for sendData() clobbering TXBUF.
* May solve a loss of UART TX chars.
* USCI UartStream.send() gains nothing by immediately sending the 1st byte.
* m_sobuf cannot be null in Interrupts.tx, so remove the check.
---
 tos/chips/msp430/usci/Msp430SpiP.nc  |  1 +
 tos/chips/msp430/usci/Msp430UartP.nc | 12 ++++--------
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/tos/chips/msp430/usci/Msp430SpiP.nc b/tos/chips/msp430/usci/Msp430SpiP.nc
index 22bfbbd3..142edb7b 100644
--- a/tos/chips/msp430/usci/Msp430SpiP.nc
+++ b/tos/chips/msp430/usci/Msp430SpiP.nc
@@ -250,6 +250,7 @@ implementation {
 
       if (end > m_len)
 	end = m_len;
+      waitOnTx(); /* Don't assume that the last tx is done already */
       call Registers.setTxbuf(m_txBuf ? m_txBuf[m_pos] : 0);
       while (++m_pos < end) {
 	waitOnRx();
diff --git a/tos/chips/msp430/usci/Msp430UartP.nc b/tos/chips/msp430/usci/Msp430UartP.nc
index dcdc5b38..a4bec076 100644
--- a/tos/chips/msp430/usci/Msp430UartP.nc
+++ b/tos/chips/msp430/usci/Msp430UartP.nc
@@ -146,14 +146,9 @@ implementation {
     atomic {
       if (m_sobuf || !buf || !len)
 	return FAIL;
-      m_sobuf = buf;
-      m_solen = len;
-      while (!call Registers.getIfgTx());
+      m_sbuf = m_sobuf = buf;
+      m_slen = m_solen = len;
       call Registers.setIeTx();
-      call Registers.setTxbuf(*m_sobuf);
-      m_slen = m_solen - 1;
-      if (m_slen)
-	m_sbuf = m_sobuf + 1;
       return SUCCESS;
     }
   }
@@ -163,12 +158,13 @@ implementation {
     /* FIXME: this can cause an arbitrarily long ISR, if m_slen is large.
      * But depending on timing, we may always only write 1 byte.
      */
+    while (!call Registers.getIfgTx()); /* in case interleaved UB.send */
     while (m_slen && call Registers.getIfgTx()) {
       call Registers.setTxbuf(*m_sbuf);
       if (--m_slen)
 	m_sbuf++;
     }
-    if (m_slen == 0 && m_sobuf) {
+    if (m_slen == 0) {
       call Registers.clrIeTx();
       m_sobuf = 0;
       signal UartStream.sendDone(m_sobuf, m_solen, SUCCESS);
-- 
2.39.2