Add framework in NxConsole to support VT100 escape sequences

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4542 42af7a65-404d-4744-a932-0658087f49c3

ChangeLog

@@ -2608,3 +2608,7 @@
 	  NuttShell (NSH) within an NX window.
 	* graphics/nxconsole/nxcon_sem.c:  Add protection from re-entrance with debug
 	  is enabled.
+	* include/nuttx/ascii.h and vt100.h:  Header files to centralize ASCII and
+	  VT100 escape sequence definitions.
+	* graphics/nxconsole/nxcon_vt100.c:  Add add framework to support VT100 escape
+	  sequences in NxConsole.

Documentation/NXGraphicsSubsystem.html

@@ -3376,7 +3376,7 @@ int nxf_convert_32bpp(FAR uint32_t *dest, uint16_t height,
     <dt><code>CONFIG_NXCONSOLE_CACHESIZE</code>:
       <dd>If <code>CONFIG_NXCONSOLE_FONTCACHE</code>, then this setting will control the size of the font cache (in number of glyphs).  Default: 16.
     <dt><code>CONFIG_NXCONSOLE_LINESEPARATION</code>:
-      <dd>This the space (in rows) between each row of test.  Default: 2
+      <dd>This the space (in rows) between each row of test.  Default: 0
     <dt><code>CONFIG_NXCONSOLE_NOWRAP</code>:
       <dd>By default, lines will wrap when the test reaches the right hand side of the window.
       This setting can be defining to change this behavior so that the text is simply truncated until a new line is  encountered.

graphics/README.txt

@@ -346,7 +346,7 @@ CONFIG_NXCONSOLE_CACHESIZE
   If CONFIG_NXCONSOLE_FONTCACHE, then this setting will control the size
   of the font cache (in number of glyphs).  Default: 16.
 CONFIG_NXCONSOLE_LINESEPARATION
-  This the space (in rows) between each row of test.  Default: 2
+  This the space (in rows) between each row of test.  Default: 0
 CONFIG_NXCONSOLE_NOWRAP
   By default, lines will wrap when the test reaches the right hand side
   of the window. This setting can be defining to change this behavior so

graphics/nxconsole/Make.defs

@@ -34,9 +34,10 @@
 ############################################################################
 
 NXCON_ASRCS  =
-NXCON_CSRCS  = nx_register.c nxcon_driver.c nxcon_font.c nxcon_redraw.c
+NXCON_CSRCS  = nx_register.c nxcon_driver.c nxcon_font.c nxcon_putc.c
-NXCON_CSRCS += nxcon_register.c nxcon_scroll.c nxcon_unregister.c
+NXCON_CSRCS += nxcon_redraw.c nxcon_register.c nxcon_scroll.c
-NXCON_CSRCS += nxtk_register.c nxtool_register.c 
+NXCON_CSRCS += nxcon_vt100.c nxcon_unregister.c nxtk_register.c
+NXCON_CSRCS += nxtool_register.c 
 
 ifeq ($(CONFIG_DEBUG),y)
 NXCON_CSRCS += nxcon_sem.c 

graphics/nxconsole/nxcon_driver.c

@@ -124,9 +124,9 @@ static ssize_t nxcon_write(FAR struct file *filep, FAR const char *buffer,
                            size_t buflen)
 {
   FAR struct nxcon_state_s *priv;
+  enum nxcon_vt100state_e state;
   ssize_t remaining;
   char ch;
-  int lineheight;
   int ret;
 
   /* Recover our private state structure */
@@ -144,56 +144,78 @@ static ssize_t nxcon_write(FAR struct file *filep, FAR const char *buffer,
 
   /* Loop writing each character to the display */
 
-  lineheight = (priv->fheight + CONFIG_NXCONSOLE_LINESEPARATION);
-
   for (remaining = (ssize_t)buflen; remaining > 0; remaining--)
     {
-      /* Ignore carriage returns */
+      /* Get the next character from the user buffer */
 
       ch = *buffer++;
-      if (ch == '\r')
+
+      /* Check if this character is part of a VT100 escape sequence */
+
+      do
         {
-          continue;
+          /* Is the character part of a VT100 escape sequnce? */
-        }
 
-      /* Will another character fit on this line? */
+          state = nxcon_vt100(priv, ch);
-
+          switch (state)
-      if (priv->fpos.x + priv->fwidth > priv->wndo.wsize.w)
             {
-#ifndef CONFIG_NXCONSOLE_NOWRAP
+              /* Character is not part of a VT100 escape sequence (and no
-          /* No.. move to the next line */
+               * characters are buffer.
-
-          nxcon_newline(priv);
-
-          /* If we were about to output a newline character, then don't */
-
-          if (ch == '\n')
-            {
-              continue;
-            }
-#else
-          /* No.. Ignore all further characters until a newline is encountered */
-
-          if (ch != '\n')
-            {
-              continue;
-            }
-#endif
-        }
-
-      /* Check if we need to scroll up (handling a corner case where
-       * there may be more than one newline).
                */
 
-      while (priv->fpos.y >= priv->wndo.wsize.h - lineheight)
+              default:
+              case VT100_NOT_CONSUMED:
                 {
-          nxcon_scroll(priv, lineheight);
+                  /* We can output the character to the window */
-        }
-
-      /* Finally, we can output the character */
 
                   nxcon_putc(priv, (uint8_t)ch);
                 }
+              break;
+
+            /* The full VT100 escape sequence was processed (and the new
+             * character was consumed)
+             */
+
+            case VT100_PROCESSED:
+
+            /* Character was consumed as part of the VT100 escape processing
+             * (but the escape sequence is still incomplete.
+             */
+
+            case VT100_CONSUMED: 
+              {
+                /* Do nothing... the VT100 logic owns the character */
+              }
+              break;
+
+            /* Invalid/unsupported character in escape sequence */
+
+            case VT100_ABORT:
+              {
+                int i;
+
+                /* Add the first unhandled character to the window */
+
+                nxcon_putc(priv, (uint8_t)priv->seq[0]);
+
+                /* Move all buffer characters down one */
+
+                for (i = 1; i < priv->nseq; i++)
+                  {
+                    priv->seq[i-1] = priv->seq[i];
+                  }
+                priv->nseq--;
+
+                /* Then loop again and check if what remains is part of a
+                 * VT100 escape sequence.  We could speed this up by
+                 * checking if priv->seq[0] == ASCII_ESC.
+                 */
+              }
+              break;
+            }
+        }
+      while (state == VT100_ABORT);
+    }
 
   nxcon_sempost(priv);
   return (ssize_t)buflen;

graphics/nxconsole/nxcon_font.c

@@ -39,20 +39,9 @@
 
 #include <nuttx/config.h>
 
-#include <stdint.h>
+#include <assert.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <ctype.h>
-#include <errno.h>
 #include <debug.h>
 
-#include <nuttx/kmalloc.h>
-
-#include <nuttx/nx/nx.h>
-#include <nuttx/nx/nxtk.h>
-#include <nuttx/nx/nxfonts.h>
-
 #include "nxcon_internal.h"
 
 /****************************************************************************
@@ -410,6 +399,10 @@ nxcon_getglyph(NXHANDLE hfont, FAR struct nxcon_state_s *priv, uint8_t ch)
   return glyph;
 }
 
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
 /****************************************************************************
  * Name: nxcon_addchar
  *
@@ -419,7 +412,7 @@ nxcon_getglyph(NXHANDLE hfont, FAR struct nxcon_state_s *priv, uint8_t ch)
  *
  ****************************************************************************/
 
-static FAR const struct nxcon_bitmap_s *
+FAR const struct nxcon_bitmap_s *
 nxcon_addchar(NXHANDLE hfont, FAR struct nxcon_state_s *priv, uint8_t ch)
 {
   FAR struct nxcon_bitmap_s *bm = NULL;
@@ -465,10 +458,6 @@ nxcon_addchar(NXHANDLE hfont, FAR struct nxcon_state_s *priv, uint8_t ch)
   return bm;
 }
 
-/****************************************************************************
- * Public Functions
- ****************************************************************************/
-
 /****************************************************************************
  * Name: nxcon_home
  *
@@ -507,41 +496,6 @@ void nxcon_newline(FAR struct nxcon_state_s *priv)
   priv->fpos.y += (priv->fheight + CONFIG_NXCONSOLE_LINESEPARATION);
 }
 
-/****************************************************************************
- * Name: nxcon_putc
- *
- * Description:
- *   Render the specified character at the current display position.
- *
- ****************************************************************************/
-
-void nxcon_putc(FAR struct nxcon_state_s *priv, uint8_t ch)
-{
-  FAR const struct nxcon_bitmap_s *bm;
-
-  /* If it is a newline character, then just perform the logical newline
-   * operation.
-   */
-
-  if (ch == '\n')
-    {
-      nxcon_newline(priv);
-    }
-
-  /* Otherwise, find the glyph associated with the character and render it
-   * onto the display.
-   */
-
-  else
-    {
-      bm = nxcon_addchar(priv->font, priv, ch);
-      if (bm)
-        {
-          nxcon_fillchar(priv, NULL, bm);
-        }
-    }
-}
-
 /****************************************************************************
  * Name: nxcon_fillchar
  *

graphics/nxconsole/nxcon_internal.h

@@ -74,9 +74,22 @@
 
 #define NO_HOLDER          (pid_t)-1
 
+/* VT100 escape sequence processing */
+
+#define VT100_MAX_SEQUENCE 3
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
+/* Identifies the state of the VT100 escape sequence processing */
+
+enum nxcon_vt100state_e
+{
+  VT100_NOT_CONSUMED = 0, /* Character is not part of a VT100 escape sequence */
+  VT100_CONSUMED,         /* Character was consumed as part of the VT100 escape processing */
+  VT100_PROCESSED,        /* The full VT100 escape sequence was processed */
+  VT100_ABORT             /* Invalid/unsupported character in buffered escape sequence */
+};
 
 /* Describes on set of console window callbacks */
 
@@ -146,6 +159,11 @@ struct nxcon_state_s
   uint8_t maxglyphs;                        /* Size of the glyph[] array */
 #endif
 
+  /* VT100 escape sequence processing */
+
+  char seq[VT100_MAX_SEQUENCE];             /* Buffered characters */
+  uint8_t nseq;                             /* Number of buffered characters */
+
   /* Font cache data storage */
 
   struct nxcon_bitmap_s bm[CONFIG_NXCONSOLE_MXCHARS];
@@ -188,11 +206,17 @@ FAR struct nxcon_state_s *nxcon_register(NXCONSOLE handle,
     FAR struct nxcon_window_s *wndo, FAR const struct nxcon_operations_s *ops,
     int minor);
 
+/* VT100 Terminal emulation */
+
+enum nxcon_vt100state_e nxcon_vt100(FAR struct nxcon_state_s *priv, char ch);
+
 /* Generic text display helpers */
 
 void nxcon_home(FAR struct nxcon_state_s *priv);
 void nxcon_newline(FAR struct nxcon_state_s *priv);
 void nxcon_putc(FAR struct nxcon_state_s *priv, uint8_t ch);
+FAR const struct nxcon_bitmap_s *nxcon_addchar(NXHANDLE hfont,
+    FAR struct nxcon_state_s *priv, uint8_t ch);
 void nxcon_fillchar(FAR struct nxcon_state_s *priv,
     FAR const struct nxgl_rect_s *rect, FAR const struct nxcon_bitmap_s *bm);
 

graphics/nxconsole/nxcon_putc.c

@@ -0,0 +1,140 @@
+/****************************************************************************
+ * nuttx/graphics/nxconsole/nxcon_putc.c
+ *
+ *   Copyright (C) 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
+ * 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include "nxcon_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxcon_putc
+ *
+ * Description:
+ *   Render the specified character at the current display position.
+ *
+ ****************************************************************************/
+
+void nxcon_putc(FAR struct nxcon_state_s *priv, uint8_t ch)
+{
+  FAR const struct nxcon_bitmap_s *bm;
+  int lineheight;
+
+  /* Ignore carriage returns */
+
+  if (ch == '\r')
+    {
+      return;
+    }
+
+  /* Will another character fit on this line? */
+
+  if (priv->fpos.x + priv->fwidth > priv->wndo.wsize.w)
+    {
+#ifndef CONFIG_NXCONSOLE_NOWRAP
+      /* No.. move to the next line */
+
+      nxcon_newline(priv);
+
+      /* If we were about to output a newline character, then don't */
+
+      if (ch == '\n')
+        {
+          return;
+        }
+#else
+      /* No.. Ignore all further characters until a newline is encountered */
+
+      if (ch != '\n')
+        {
+          return;
+        }
+#endif
+    }
+
+  /* If it is a newline character, then just perform the logical newline
+   * operation.
+   */
+
+  if (ch == '\n')
+    {
+      nxcon_newline(priv);
+      return;
+    }
+
+  /* Check if we need to scroll up */
+
+  lineheight = (priv->fheight + CONFIG_NXCONSOLE_LINESEPARATION);
+  while (priv->fpos.y >= priv->wndo.wsize.h - lineheight)
+    {
+      nxcon_scroll(priv, lineheight);
+    }
+
+  /* Find the glyph associated with the character and render it onto the
+   * display.
+   */
+
+  bm = nxcon_addchar(priv->font, priv, ch);
+  if (bm)
+    {
+      nxcon_fillchar(priv, NULL, bm);
+    }
+}

graphics/nxconsole/nxcon_sem.c

@@ -1,5 +1,5 @@
 /****************************************************************************
- * nuttx/graphics/nxconsole/nxcon_unregister.c
+ * nuttx/graphics/nxconsole/nxcon_sem.c
  *
  *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>

graphics/nxconsole/nxcon_vt100.c

@@ -0,0 +1,289 @@
+/****************************************************************************
+ * nuttx/graphics/nxconsole/nxcon_vt100.c
+ *
+ *   Copyright (C) 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
+ * 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <string.h>
+#include <assert.h>
+
+#include <nuttx/vt100.h>
+
+#include "nxcon_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+typedef int (*seqhandler_t)(FAR struct nxcon_state_s *priv);
+
+struct vt100_sequence_s
+{
+  FAR const char *seq;
+  seqhandler_t handler;
+  uint8_t size;
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int nxcon_erasetoeol(FAR struct nxcon_state_s *priv);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* All recognized VT100 escape sequences.  Very little as present, this is
+ * a placeholder for a future, more complete VT100 emulation.
+ */
+
+/* <esc>[K is the VT100 command erases to the end of the line. */
+
+static const char g_erasetoeol[] = VT100_CLEAREOL;
+
+/* The list of all VT100 sequences supported by the emulation */
+
+static const struct vt100_sequence_s g_vt100sequences[] =
+{
+  {g_erasetoeol, nxcon_erasetoeol, sizeof(g_erasetoeol)},
+  {NULL, NULL, 0}
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxcon_erasetoeol
+ *
+ * Description:
+ *   Handle the erase-to-eol VT100 escapte sequence
+ *
+ * Input Parameters:
+ *   priv - Driver data structure
+ *
+ * Returned Value:
+ *   The index of the match in g_vt100sequences[]
+ *
+ ****************************************************************************/
+
+static int nxcon_erasetoeol(FAR struct nxcon_state_s *priv)
+{
+  /* Does nothing yet (other than consume the sequence) */
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: nxcon_vt100part
+ *
+ * Description:
+ *   Return the next entry that is a partial match to the sequence.
+ *
+ * Input Parameters:
+ *   priv - Driver data structure
+ *   seqsize - The number of bytes in the sequence
+ *   startndx - The index to start searching
+ *
+ * Returned Value:
+ *   A pointer to the matching sequence in g_vt100sequences[]
+ *
+ ****************************************************************************/
+
+FAR const struct vt100_sequence_s *
+nxcon_vt100part(FAR struct nxcon_state_s *priv, int seqsize)
+{
+  FAR const struct vt100_sequence_s *seq;
+  int ndx;
+
+  /* Search from the beginning of the sequence table */
+
+  for (ndx = 0; g_vt100sequences[ndx].seq; ndx++)
+    {
+      /* Is this sequence big enough? */
+
+      seq = &g_vt100sequences[ndx];
+      if (seq->size >= seqsize)
+        {
+          /* Yes... are the first 'seqsize' bytes the same */
+
+          if (memcmp(seq->seq, priv->seq, seqsize) == 0)
+            {
+              /* Yes.. return the match */
+
+              return seq;
+            }
+        }
+    }
+  return NULL;
+}
+
+/****************************************************************************
+ * Name: nxcon_vt100seq
+ *
+ * Description:
+ *   Determine if the new sequence is a part of a supported VT100 escape
+ *   sequence.
+ *
+ * Input Parameters:
+ *   priv - Driver data structure
+ *   seqsize - The number of bytes in the sequence
+ *
+ * Returned Value:
+ *   state - See enum nxcon_vt100state_e;
+ *
+ ****************************************************************************/
+
+static enum nxcon_vt100state_e nxcon_vt100seq(FAR struct nxcon_state_s *priv,
+                                              int seqsize)
+{
+  FAR const struct vt100_sequence_s *seq;
+  enum nxcon_vt100state_e ret;
+
+  /* Is there any VT100 escape sequence that matches what we have
+   * buffered so far?
+   */
+
+  seq = nxcon_vt100part(priv, seqsize);
+  if (seq)
+    {
+      /* Yes.. if the size of that escape sequence is the same as what we
+       * have buffered, then we have an exact match.
+       */
+
+      if (seq->size == seqsize)
+        {
+          /* Process the VT100 sequence */
+
+          seq->handler(priv);
+          priv->nseq = 0;
+          return VT100_PROCESSED;
+        }
+
+      /* The 'seqsize' is still smaller than the potential match(es).  We
+       * will need to collect more characters before we can make a decision.
+       * Retun an indication that we have consumed the character.
+       */
+
+      return VT100_CONSUMED;
+    }
+
+  /* We get here on a failure.  The buffer sequence is not part of any
+   * supported VT100 escape sequence.  If seqsize > 1 then we need to
+   * return a special value because we have to re-process the buffered
+   * data.
+   */
+
+  ret = seqsize > 1 ? VT100_ABORT : VT100_NOT_CONSUMED;
+  return ret;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxcon_vt100
+ *
+ * Description:
+ *   Test if the newly received byte is part of a VT100 escape sequence
+ *
+ * Input Parameters:
+ *   priv - Driver data structure
+ *   ch - The newly received character
+ *
+ * Returned Value:
+ *   state - See enum nxcon_vt100state_e;
+ *
+ ****************************************************************************/
+
+enum nxcon_vt100state_e nxcon_vt100(FAR struct nxcon_state_s *priv, char ch)
+{
+  enum nxcon_vt100state_e ret;
+  int seqsize;
+
+  DEBUGASSERT(priv && priv->nseq < VT100_MAX_SEQUENCE);
+
+  /* If we have no buffered characters, then 'ch' must be the first character
+   * of an escape sequence.
+   */
+
+  if (priv->nseq < 1)
+    {
+      /* The first character of an escape sequence must be an an escape
+       * character (duh).
+       */
+
+      if (ch != ASCII_ESC)
+        {
+          return VT100_NOT_CONSUMED;
+        }
+
+      /* Add the escape character to the buffer but don't bother with any
+       * further checking.
+       */
+
+      priv->seq[0] = ASCII_ESC;
+      priv->nseq   = 1;
+      return VT100_CONSUMED;
+    }
+
+  /* Temporarily add the next character to the buffer */
+
+  seqsize = priv->nseq;
+  priv->seq[seqsize] = ch;
+
+  /* Then check if this sequence is part of an a valid escape sequence */
+
+  seqsize++;
+  ret = nxcon_vt100seq(priv, seqsize);
+  if (ret == VT100_CONSUMED)
+    {
+      /* The newly added character is indeed part of a VT100 escape sequence
+       * (which is still incomplete).  Keep it in the buffer.
+       */
+
+      priv->nseq = seqsize;
+    }
+  return ret;
+}

include/nuttx/nx/nxconsole.h

@@ -87,7 +87,7 @@
  *   If CONFIG_NXCONSOLE_FONTCACHE, then this setting will control the size
  *   of the font cache (in number of glyphs).  Default: 16.
  * CONFIG_NXCONSOLE_LINESEPARATION
- *   This the space (in rows) between each row of test.  Default: 2
+ *   This the space (in rows) between each row of test.  Default: 0
  * CONFIG_NXCONSOLE_NOWRAP
  *   By default, lines will wrap when the test reaches the right hand side
  *   of the window. This setting can be defining to change this behavior so
@@ -137,7 +137,7 @@
 /* Space (in rows) between lines */
 
 #ifndef CONFIG_NXCONSOLE_LINESEPARATION
-#  define CONFIG_NXCONSOLE_LINESEPARATION 2
+#  define CONFIG_NXCONSOLE_LINESEPARATION 0
 #endif
 
 /****************************************************************************