From ca8fe618e7411148edebae394fe2d1c54bee5134 Mon Sep 17 00:00:00 2001
From: Simon Duquennoy <simonduq@sics.se>
Date: Tue, 6 Oct 2015 16:12:24 +0200
Subject: [PATCH] cc2420 and cc2430: add comment on why we discard tbiv

---
 cpu/msp430/cc2420-arch-sfd.c | 1 +
 cpu/msp430/cc2520-arch-sfd.c | 1 +
 dev/cc2520/cc2520.c          | 1 +
 3 files changed, 3 insertions(+)

diff --git a/cpu/msp430/cc2420-arch-sfd.c b/cpu/msp430/cc2420-arch-sfd.c
index a940b8cab..6cd7d2606 100644
--- a/cpu/msp430/cc2420-arch-sfd.c
+++ b/cpu/msp430/cc2420-arch-sfd.c
@@ -45,6 +45,7 @@ ISR(TIMERB1, cc2420_timerb1_interrupt)
   ENERGEST_ON(ENERGEST_TYPE_IRQ);
   /* always read TBIV to clear IFG */
   tbiv = TBIV;
+  /* read and discard tbiv to avoid "variable set but not used" warning */
   (void)tbiv;
   if(CC2420_SFD_IS_1) {
     cc2420_sfd_counter++;
diff --git a/cpu/msp430/cc2520-arch-sfd.c b/cpu/msp430/cc2520-arch-sfd.c
index 852974b70..5e7bee813 100644
--- a/cpu/msp430/cc2520-arch-sfd.c
+++ b/cpu/msp430/cc2520-arch-sfd.c
@@ -44,6 +44,7 @@ ISR(TIMERB1, cc2520_timerb1_interrupt)
   ENERGEST_ON(ENERGEST_TYPE_IRQ);
   /* always read TBIV to clear IFG */
   tbiv = TBIV;
+  /* read and discard tbiv to avoid "variable set but not used" warning */
   (void)tbiv;
   if(CC2520_SFD_IS_1) {
     cc2520_sfd_counter++;
diff --git a/dev/cc2520/cc2520.c b/dev/cc2520/cc2520.c
index 3b40c8879..e0dad1b6a 100644
--- a/dev/cc2520/cc2520.c
+++ b/dev/cc2520/cc2520.c
@@ -217,6 +217,7 @@ flushrx(void)
   uint8_t dummy;
 
   CC2520_READ_FIFO_BYTE(dummy);
+  /* read and discard dummy to avoid "variable set but not used" warning */
   (void)dummy;
   CC2520_STROBE(CC2520_INS_SFLUSHRX);
   CC2520_STROBE(CC2520_INS_SFLUSHRX);