Simulated UART seems functional

arch/sim/src/host.h

-/**************************************************************************
- * arch/sim/src/host.h
- *
- *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
- *   Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- *    used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- **************************************************************************/
-
-#ifndef __ARCH_SIM_SRC_HOST_H
-#define __ARCH_SIM_SRC_HOST_H
-
-/**************************************************************************
- * Included Files
- **************************************************************************/
-
-/**************************************************************************
- * Pre-processor Definitions
- **************************************************************************/
-
-/**************************************************************************
- * Public Types
- **************************************************************************/
-
-/**************************************************************************
- * Public Variables
- **************************************************************************/
-
-#ifndef __ASSEMBLY__
-
-/**************************************************************************
- * Public Function Prototypes
- **************************************************************************/
-
-/* up_uartwait.c **********************************************************/
-/* Exported to Nuttx domain files to host domain files */
-
-void simuart_initialize(void);
-void simuart_post(void);
-void simuart_wait(void);
-
-#endif /* __ASSEMBLY__ */
-#endif /* __ARCH_SIM_SRC_HOST_H */

arch/sim/src/up_simuart.c

@@ -41,8 +41,6 @@
 #include <termios.h>
 #include <pthread.h>
 
-#include "host.h"
-
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -60,6 +58,17 @@ static char g_uartbuffer[SIMUART_BUFSIZE];
 static volatile int  g_uarthead;
 static volatile int  g_uarttail;
 
+/****************************************************************************
+ * NuttX Domain Public Function Prototypes
+ ****************************************************************************/
+
+void sched_lock(void);
+void sched_unlock(void);
+
+void simuart_initialize(void);
+void simuart_post(void);
+void simuart_wait(void);
+
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -91,10 +100,8 @@ static void *simuart_thread(void *arg)
 {
   unsigned char ch;
   ssize_t nread;
-
-  /* Put stdin into raw mode */
-
-  setrawmode();
+  int next;
+  int prev;
 
   /* Now loop, collecting a buffering data from stdin forever */
 
@@ -108,9 +115,12 @@ static void *simuart_thread(void *arg)
 
       if (nread == 1)
         {
+          sched_lock();
+
           /* Get the index to the next slot in the UART buffer */
 
-          int next = g_uarthead + 1;
+          prev = g_uarthead;
+          next = prev + 1;
           if (next >= SIMUART_BUFSIZE)
             {
               next = 0;
@@ -122,11 +132,15 @@ static void *simuart_thread(void *arg)
             {
               /* No.. Add the character to the UART buffer */
 
-              g_uartbuffer[g_uarthead] = ch;
+              g_uartbuffer[prev] = ch;
+
+              /* Update the head index (BEFORE posting) */
+
+              g_uarthead = next;
 
               /* Was the buffer previously empty? */
 
-              if (g_uarthead == g_uarttail)
+              if (prev == g_uarttail)
                 {
                   /* Yes.. signal any (NuttX) threads waiting for serial
                    * input.
@@ -134,11 +148,9 @@ static void *simuart_thread(void *arg)
 
                   simuart_post();
                 }
-
-              /* Update the head index */
-
-              g_uarthead = next;
             }
+
+          sched_unlock();
         }
     }
 
@@ -179,6 +191,10 @@ void simuart_start(void)
 
   simuart_initialize();
 
+  /* Put stdin into raw mode */
+
+  setrawmode();
+
   /* Start the simulated UART thread -- all default settings; no error
    * checking.
    */
@@ -224,7 +240,7 @@ int simuart_getc(void)
 
       /* The UART buffer show be non-empty... check anyway */
 
-      if (g_uarthead == g_uarttail)
+      if (g_uarthead != g_uarttail)
         {
           /* Take the next byte from the tail of the buffer */