Fix a divide-by-zero error in the trapezoid drawing logic

git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@4807 7fd9a85b-ad96-42d3-883c-3090e2eb8679

5 files changed, 41 insertions, 11 deletions

diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index 5b3063c30..7b32ae20f 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -2896,4 +2896,8 @@
 	  when the work queue is enabled.  This is partially because some interrupt
 	  related logic is not built in that case.  Simply disabling then re-
 	  enabling interrupts restores the proper state.
+	* graphics/nxglib/lcd/nxglib_filltrapezoid.c and fb/nxglib_filltrapezoid.c:
+	  Fix an error when the trapezoid is only 1 line high.  In this case, a
+	  divide by zero error would occur.  The fix is to draw the 1 line high
+	  trapezoid as a run.
 
diff --git a/nuttx/Documentation/NuttX.html b/nuttx/Documentation/NuttX.html
index a467917f0..8a4489ff6 100644
--- a/nuttx/Documentation/NuttX.html
+++ b/nuttx/Documentation/NuttX.html
@@ -2275,7 +2275,7 @@
       <p>
        <b>STATUS:</b>
          Two verified configurations are available:
-         (1) The basic OS test configuration that verfies the correctnexx port of Nuttx, and (2) an extensive <a href="NuttShell.html">NuttShell (NSH)</a> configuration.
+         (1) The basic OS test configuration that verfies the correctness port of Nuttx, and (2) an extensive <a href="NuttShell.html">NuttShell (NSH)</a> configuration.
          The NSH configuration includes:
          (1) Full network support,
          (2) Verified SPI driver,
diff --git a/nuttx/configs/pic32mx7mmb/nsh/appconfig b/nuttx/configs/pic32mx7mmb/nsh/appconfig
index 99292fc2b..faa1f49ce 100644
--- a/nuttx/configs/pic32mx7mmb/nsh/appconfig
+++ b/nuttx/configs/pic32mx7mmb/nsh/appconfig
@@ -65,7 +65,7 @@ ifeq ($(CONFIG_CDCACM),y)
   CONFIGURED_APPS += examples/cdcacm
 # Uncomment the following to enable the examples/usbterm built-in
 # CONFIGURED_APPS += examples/usbterm
-#else
+else
 
 # Prolifics PL2303 emulation configurations
 
diff --git a/nuttx/graphics/nxglib/fb/nxglib_filltrapezoid.c b/nuttx/graphics/nxglib/fb/nxglib_filltrapezoid.c
index 64554fae1..7623bf84f 100644
--- a/nuttx/graphics/nxglib/fb/nxglib_filltrapezoid.c
+++ b/nuttx/graphics/nxglib/fb/nxglib_filltrapezoid.c
@@ -1,8 +1,8 @@
 /****************************************************************************
  * graphics/nxglib/fb/nxglib_filltrapezoid.c
  *
- *   Copyright (C) 2008-2011 Gregory Nutt. All rights reserved.
- *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *   Copyright (C) 2008-2012 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
@@ -126,8 +126,20 @@ void NXGL_FUNCNAME(nxgl_filltrapezoid,NXGLIB_SUFFIX)(
 
   /* Calculate the slope of the left and right side of the trapezoid */
 
-  dx1dy = b16divi((trap->bot.x1 - x1), nrows - 1);
-  dx2dy = b16divi((trap->bot.x2 - x2), nrows - 1);
+  if (nrows > 1)
+    {
+      dx1dy = b16divi((trap->bot.x1 - x1), nrows - 1);
+      dx2dy = b16divi((trap->bot.x2 - x2), nrows - 1);
+    }
+  else
+    {
+      /* The trapezoid is a run! Use the average width. */
+
+      x1    = (x1 + trap->bot.x1) >> 1;
+      x2    = (x2 + trap->bot.x2) >> 1;
+      dx1dy = 0;
+      dx2dy = 0;
+    }
 
   /* Perform vertical clipping */
 
diff --git a/nuttx/graphics/nxglib/lcd/nxglib_filltrapezoid.c b/nuttx/graphics/nxglib/lcd/nxglib_filltrapezoid.c
index 0653da413..3ba44b34a 100644
--- a/nuttx/graphics/nxglib/lcd/nxglib_filltrapezoid.c
+++ b/nuttx/graphics/nxglib/lcd/nxglib_filltrapezoid.c
@@ -1,8 +1,8 @@
 /****************************************************************************
  * graphics/nxglib/lcd/nxglib_filltrapezoid.c
  *
- *   Copyright (C) 2010-2011 Gregory Nutt. All rights reserved.
- *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *   Copyright (C) 2010-2012 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
@@ -124,9 +124,23 @@ void NXGL_FUNCNAME(nxgl_filltrapezoid,NXGLIB_SUFFIX)
 
   /* Calculate the slope of the left and right side of the trapezoid */
 
-  dy     = boty - topy;
-  dx1dy  = b16divi((botx1 - topx1), dy);
-  dx2dy  = b16divi((botx2 - topx2), dy);
+  dy = boty - topy;
+  if (dy > 0)
+    {
+      dx1dy  = b16divi((botx1 - topx1), dy);
+      dx2dy  = b16divi((botx2 - topx2), dy);
+    }
+  else
+    {
+      /* The trapezoid is a run! Use the average width. */
+
+      topx1  = (topx1 + botx1) >> 1;
+      topx2  = (topx2 + botx2) >> 1;
+      botx1  = topx1;
+      botx2  = topx2;
+      dx1dy  = 0;
+      dx2dy  = 0;
+    }
 
   /* Perform vertical clipping */