4 files changed, 27 insertions, 2 deletions
diff --git a/sim/msp430/ChangeLog b/sim/msp430/ChangeLog
index 324a6fc..0f27982 100644
--- a/sim/msp430/ChangeLog
+++ b/sim/msp430/ChangeLog
@@ -1,3 +1,8 @@
+2020-01-22  Jozef Lawrynowicz  <jozef.l@mittosystems.com>
+
+	* msp430-sim.c (msp430_step_once): Ignore the carry flag when executing
+	an RRC instruction, if the ZC bit of the extension word is set.
+
 2017-09-06  John Baldwin  <jhb@FreeBSD.org>
 
 	* configure: Regenerate.
diff --git a/sim/msp430/msp430-sim.c b/sim/msp430/msp430-sim.c
index cdb8eab..e21c8cf 100644
--- a/sim/msp430/msp430-sim.c
+++ b/sim/msp430/msp430-sim.c
@@ -1292,8 +1292,10 @@ msp430_step_once (SIM_DESC sd)
 	  u1 = SRC;
 	  carry_to_use = u1 & 1;
 	  uresult = u1 >> 1;
-	  if (SR & MSP430_FLAG_C)
-	  uresult |= (1 << (opcode->size - 1));
+	  /* If the ZC bit of the opcode is set, it means we are synthesizing
+	     RRUX, so the carry bit must be ignored.  */
+	  if (opcode->zc == 0 && (SR & MSP430_FLAG_C))
+	    uresult |= (1 << (opcode->size - 1));
 	  TRACE_ALU (MSP430_CPU (sd), "RRC: %#x >>= %#x",
 		     u1, uresult);
 	  DEST (uresult);
diff --git a/sim/testsuite/sim/msp430/ChangeLog b/sim/testsuite/sim/msp430/ChangeLog
index 458ee21..7dc370f 100644
--- a/sim/testsuite/sim/msp430/ChangeLog
+++ b/sim/testsuite/sim/msp430/ChangeLog
@@ -1,3 +1,7 @@
+2020-01-22  Jozef Lawrynowicz  <jozef.l@mittosystems.com>
+
+	* rrux.s: New test.
+
 2016-01-05  Nick Clifton  <nickc@redhat.com>
 
 	* testutils.inc (__pass): Use the LMA addresses of the _passmsg
diff --git a/sim/testsuite/sim/msp430/rrux.s b/sim/testsuite/sim/msp430/rrux.s
new file mode 100644
index 0000000..07fc8d5
--- /dev/null
+++ b/sim/testsuite/sim/msp430/rrux.s
@@ -0,0 +1,14 @@
+# check that rrux (synthesized as rrc with ZC bit set) works.
+# mach: msp430
+
+.include "testutils.inc"
+
+	start
+
+	setc		; set the carry bit to ensure ZC bit is obeyed
+	mov.w	#16, r10
+	rrux.w	r10
+	cmp.w	#8, r10
+	jeq 1f
+	fail
+	1: pass