SIM: Fix simulated console... it needs to return immediately when even one byte is read

arch/sim/src/up_devconsole.c

@@ -86,23 +86,41 @@ static const struct file_operations devconsole_fops =
 static ssize_t devconsole_read(struct file *filep, char *buffer, size_t len)
 {
   size_t remaining = len;
+  ssize_t nread;
   int ch;
 
   /* Loop until all requested bytes have been read.  No error checking */
 
-  for (remaining = len; remaining > 0; remaining--)
+  sched_lock();
+  for (remaining = len, nread = 0; remaining > 0; remaining--)
     {
+      /* Read the next character from the console, we should only wait
+       * on the first read.
+       */
+
       ch = simuart_getc();
       if (ch < 0)
         {
           set_errno(EIO);
+          sched_unlock();
           return ERROR;
         }
 
       *buffer++ = ch;
+	  nread++;
+
+      /* We have at least one character.  Return now if no further
+       * characters are available without waiting.
+       */
+
+      if (!simuart_checkc())
+        {
+          break;
+        }
     }
 
-  return len;
+  sched_unlock();
+  return nread;
 }
 
 /****************************************************************************

arch/sim/src/up_internal.h

@@ -42,9 +42,14 @@
 
 #include <nuttx/config.h>
 #include <nuttx/compiler.h>
-#include <sys/types.h>
-#include <nuttx/irq.h>
-#include <arch/irq.h>
+
+#ifndef __ASSEMBLY__
+#  include <sys/types.h>
+#  include <stdbool.h>
+
+#  include <nuttx/irq.h>
+#  include <arch/irq.h>
+#endif
 
 /**************************************************************************
  * Pre-processor Definitions
@@ -213,6 +218,7 @@ void up_registerblockdevice(void);
 void simuart_start(void);
 int simuart_putc(int ch);
 int simuart_getc(void);
+bool simuart_checkc(void);
 
 /* up_uartwait.c **********************************************************/
 
@@ -288,6 +294,7 @@ void netdriver_loop(void);
 #endif
 
 #ifdef CONFIG_SIM_SPIFLASH
+struct spi_dev_s;
 struct spi_dev_s *up_spiflashinitialize(void);
 #endif
 

arch/sim/src/up_simuart.c

@@ -37,6 +37,7 @@
  * Included Files
  ****************************************************************************/
 
+#include <stdbool.h>
 #include <unistd.h>
 #include <termios.h>
 #include <pthread.h>
@@ -274,7 +275,6 @@ int simuart_getc(void)
           simuart_wait();
         }
 
-
       /* The UART buffer is non-empty...  Take the next byte from the tail
        * of the buffer.
        */
@@ -294,3 +294,13 @@ int simuart_getc(void)
       return ch;
     }
 }
+
+/****************************************************************************
+ * Name: simuart_getc
+ ****************************************************************************/
+
+bool simuart_checkc(void)
+{
+  return g_uarthead != g_uarttail;
+}
+