Add floating point support to printf

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2656 42af7a65-404d-4744-a932-0658087f49c3

8 files changed, 1941 insertions, 8 deletions

diff --git a/nuttx/COPYING b/nuttx/COPYING
index 0fa6c256c..ffcc06ca5 100755
--- a/nuttx/COPYING
+++ b/nuttx/COPYING
@@ -3,7 +3,7 @@
  * COPYING -- Describes the terms under which Nuttx is distributed. A    *

  * copy of the BSD-style licensing is included in this file. In my       *

  * words -- I believe that you should free to use NuttX in any           *

- * environmnet, private, private, commercial, open, closed, etc.         *

+ * environment, private, private, commercial, open, closed, etc.         *

  * provided only that you repect the modest copyright notices as         *

  * described in license (below).  Please feel free to contact me if you  *

  * have any licensing concerns.                                          *

@@ -42,3 +42,10 @@
  *                                                                       *

  *************************************************************************/

 

+If you enable floating point conversions with CONFIG_LIBC_FLOATINGPOINT,

+then some files with an unmodified BSD license will be included.  That

+license is similar to the above (modified) BSD license, but has an

+additional requirement that I state the following:

+

+  "This product includes software developed by the University of

+   California, Berkeley and its contributors."

diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index 37842efc0..c4264262a 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -1114,4 +1114,9 @@
 	  LM3S6965
 	* configs/lm3s6965-ek - Add configuration for Stellaris LM3S6965
 	  Evaluation Kit.
+	* lib/lib_dtoa.c and lib/lib_dtoa.c - printf will not printf floating
+	  point values if you select CONFIG_LIBC_FLOATINGPOINT in your
+	  configuration file.  Contributed by Yolande Cates.  NOTE:  these
+	  floating point operations have not been well tested and may not
+	  be portable to all floating point implementations.
 
diff --git a/nuttx/Documentation/NuttX.html b/nuttx/Documentation/NuttX.html
index 58afda7b5..798726f26 100644
--- a/nuttx/Documentation/NuttX.html
+++ b/nuttx/Documentation/NuttX.html
@@ -8,7 +8,7 @@
   <tr align="center" bgcolor="#e4e4e4">
     <td>
       <h1><big><font color="#3c34ec"><i>NuttX RTOS</i></font></big></h1>
-      <p>Last Updated: May 6, 2010</p>
+      <p>Last Updated: May 7, 2010</p>
     </td>
   </tr>
 </table>
@@ -1722,6 +1722,11 @@ nuttx-5.5 2010-xx-xx Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
 	  LM3S6965
 	* configs/lm3s6965-ek - Add configuration for Stellaris LM3S6965
 	  Evaluation Kit.
+	* lib/lib_dtoa.c and lib/lib_dtoa.c - printf will not printf floating
+	  point values if you select CONFIG_LIBC_FLOATINGPOINT in your
+	  configuration file.  Contributed by Yolande Cates.  NOTE:  these
+	  floating point operations have not been well tested and may not
+	  be portable to all floating point implementations.
 
 pascal-2.1 2010-xx-xx Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
 
diff --git a/nuttx/lib/Makefile b/nuttx/lib/Makefile
index 612c218ed..4ca4735c1 100644
--- a/nuttx/lib/Makefile
+++ b/nuttx/lib/Makefile
@@ -1,7 +1,7 @@
 ############################################################################
 # lib/Makefile
 #
-#   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+#   Copyright (C) 2007-2010 Gregory Nutt. All rights reserved.
 #   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
 #
 # Redistribution and use in source and binary forms, with or without
@@ -71,6 +71,9 @@ STDIO_SRCS	+= lib_fopen.c lib_fclose.c lib_fread.c lib_libfread.c lib_fseek.c \
 		   lib_fprintf.c lib_vfprintf.c lib_stdinstream.c lib_stdoutstream.c
 endif
 endif
+ifeq ($(CONFIG_LIBC_FLOATINGPOINT),y)
+STDIO_SRCS	+= lib_dtoa.c
+endif
 
 STDLIB_SRCS	= lib_rand.c lib_qsort.c
 
diff --git a/nuttx/lib/lib_dtoa.c b/nuttx/lib/lib_dtoa.c
new file mode 100755
index 000000000..1bab1435f
--- /dev/null
+++ b/nuttx/lib/lib_dtoa.c
@@ -0,0 +1,1536 @@
+/****************************************************************************
+ * lib/lib_dtoa.c
+ *
+ * This file was ported to NuttX by Yolande Cates.
+ *
+ * Copyright (c) 1990, 1993
+ *      The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * 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. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by the University of
+ *      California, Berkeley and its contributors.
+ * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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 <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#ifdef Unsigned_Shifts
+#  define Sign_Extend(a,b) if (b < 0) a |= 0xffff0000;
+#else
+#  define Sign_Extend(a,b)      /* no-op */
+#endif
+
+#ifdef CONFIG_ENDIAN_BIG
+#  define word0(x) ((uint32_t *)&x)[0]
+#  define word1(x) ((uint32_t *)&x)[1]
+#else
+#  define word0(x) ((uint32_t *)&x)[1]
+#  define word1(x) ((uint32_t *)&x)[0]
+#endif
+
+#ifdef CONFIG_ENDIAN_BIG
+#  define Storeinc(a,b,c) (((unsigned short *)a)[0] = (unsigned short)b, \
+                         ((unsigned short *)a)[1] = (unsigned short)c, a++)
+#else
+#  define Storeinc(a,b,c) (((unsigned short *)a)[1] = (unsigned short)b, \
+                         ((unsigned short *)a)[0] = (unsigned short)c, a++)
+#endif
+
+#define Exp_shift  20
+#define Exp_shift1 20
+#define Exp_msk1    0x100000
+#define Exp_msk11   0x100000
+#define Exp_mask  0x7ff00000
+#define P 53
+#define Bias 1023
+#define IEEE_Arith
+#define Emin (-1022)
+#define Exp_1  0x3ff00000
+#define Exp_11 0x3ff00000
+#define Ebits 11
+#define Frac_mask  0xfffff
+#define Frac_mask1 0xfffff
+#define Ten_pmax 22
+#define Bletch 0x10
+#define Bndry_mask  0xfffff
+#define Bndry_mask1 0xfffff
+#define LSB 1
+#define Sign_bit 0x80000000
+#define Log2P 1
+#define Tiny0 0
+#define Tiny1 1
+#define Quick_max 14
+#define Int_max 14
+#define Infinite(x) (word0(x) == 0x7ff00000)    /* sufficient test for here */
+
+#define Kmax 15
+
+#define Bcopy(x,y) memcpy((char *)&x->sign, (char *)&y->sign, \
+                          y->wds*sizeof(long) + 2*sizeof(int))
+
+/****************************************************************************
+ * Private Type Definitions
+ ****************************************************************************/
+
+struct Bigint
+{
+  struct Bigint *next;
+  int k, maxwds, sign, wds;
+  unsigned long x[1];
+};
+
+typedef struct Bigint Bigint;
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static Bigint *freelist[Kmax + 1];
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static Bigint *Balloc(int k)
+{
+  int x;
+  Bigint *rv;
+
+  if ((rv = freelist[k]))
+    {
+      freelist[k] = rv->next;
+    }
+  else
+    {
+      x = 1 << k;
+      rv = (Bigint *) malloc(sizeof(Bigint) + (x - 1) * sizeof(long));
+      rv->k = k;
+      rv->maxwds = x;
+    }
+  rv->sign = rv->wds = 0;
+  return rv;
+}
+
+static void Bfree(Bigint * v)
+{
+  if (v)
+    {
+      v->next = freelist[v->k];
+      freelist[v->k] = v;
+    }
+}
+
+/* multiply by m and add a */
+
+static Bigint *multadd(Bigint * b, int m, int a)
+{
+  int i, wds;
+  unsigned long *x, y;
+#ifdef Pack_32
+  unsigned long xi, z;
+#endif
+  Bigint *b1;
+
+  wds = b->wds;
+  x = b->x;
+  i = 0;
+  do
+    {
+#ifdef Pack_32
+      xi = *x;
+      y = (xi & 0xffff) * m + a;
+      z = (xi >> 16) * m + (y >> 16);
+      a = (int)(z >> 16);
+      *x++ = (z << 16) + (y & 0xffff);
+#else
+      y = *x * m + a;
+      a = (int)(y >> 16);
+      *x++ = y & 0xffff;
+#endif
+    }
+  while (++i < wds);
+  if (a)
+    {
+      if (wds >= b->maxwds)
+        {
+          b1 = Balloc(b->k + 1);
+          Bcopy(b1, b);
+          Bfree(b);
+          b = b1;
+        }
+      b->x[wds++] = a;
+      b->wds = wds;
+    }
+  return b;
+}
+
+static int hi0bits(unsigned long x)
+{
+  int k = 0;
+
+  if (!(x & 0xffff0000))
+    {
+      k = 16;
+      x <<= 16;
+    }
+
+  if (!(x & 0xff000000))
+    {
+      k += 8;
+      x <<= 8;
+    }
+
+  if (!(x & 0xf0000000))
+    {
+      k += 4;
+      x <<= 4;
+    }
+
+  if (!(x & 0xc0000000))
+    {
+      k += 2;
+      x <<= 2;
+    }
+
+  if (!(x & 0x80000000))
+    {
+      k++;
+      if (!(x & 0x40000000))
+        {
+          return 32;
+        }
+    }
+  return k;
+}
+
+static int lo0bits(unsigned long *y)
+{
+  int k;
+  unsigned long x = *y;
+
+  if (x & 7)
+    {
+      if (x & 1)
+        {
+          return 0;
+        }
+      if (x & 2)
+        {
+          *y = x >> 1;
+          return 1;
+        }
+      *y = x >> 2;
+      return 2;
+    }
+
+  k = 0;
+  if (!(x & 0xffff))
+    {
+      k = 16;
+      x >>= 16;
+    }
+
+  if (!(x & 0xff))
+    {
+      k += 8;
+      x >>= 8;
+    }
+
+  if (!(x & 0xf))
+    {
+      k += 4;
+      x >>= 4;
+    }
+
+  if (!(x & 0x3))
+    {
+      k += 2;
+      x >>= 2;
+    }
+
+  if (!(x & 1))
+    {
+      k++;
+      x >>= 1;
+      if (!x & 1)
+        {
+          return 32;
+        }
+    }
+  *y = x;
+  return k;
+}
+
+static Bigint *i2b(int i)
+{
+  Bigint *b;
+
+  b = Balloc(1);
+  b->x[0] = i;
+  b->wds = 1;
+  return b;
+}
+
+static Bigint *mult(Bigint * a, Bigint * b)
+{
+  Bigint *c;
+  int k, wa, wb, wc;
+  unsigned long carry, y, z;
+  unsigned long *x, *xa, *xae, *xb, *xbe, *xc, *xc0;
+#ifdef Pack_32
+  uint32_t z2;
+#endif
+
+  if (a->wds < b->wds)
+    {
+      c = a;
+      a = b;
+      b = c;
+    }
+
+  k = a->k;
+  wa = a->wds;
+  wb = b->wds;
+  wc = wa + wb;
+  if (wc > a->maxwds)
+    {
+      k++;
+    }
+  c = Balloc(k);
+  for (x = c->x, xa = x + wc; x < xa; x++)
+    {
+      *x = 0;
+    }
+  xa = a->x;
+  xae = xa + wa;
+  xb = b->x;
+  xbe = xb + wb;
+  xc0 = c->x;
+#ifdef Pack_32
+  for (; xb < xbe; xb++, xc0++)
+    {
+      if ((y = *xb & 0xffff))
+        {
+          x = xa;
+          xc = xc0;
+          carry = 0;
+          do
+            {
+              z = (*x & 0xffff) * y + (*xc & 0xffff) + carry;
+              carry = z >> 16;
+              z2 = (*x++ >> 16) * y + (*xc >> 16) + carry;
+              carry = z2 >> 16;
+              Storeinc(xc, z2, z);
+            }
+          while (x < xae);
+          *xc = carry;
+        }
+      if ((y = *xb >> 16))
+        {
+          x = xa;
+          xc = xc0;
+          carry = 0;
+          z2 = *xc;
+          do
+            {
+              z = (*x & 0xffff) * y + (*xc >> 16) + carry;
+              carry = z >> 16;
+              Storeinc(xc, z, z2);
+              z2 = (*x++ >> 16) * y + (*xc & 0xffff) + carry;
+              carry = z2 >> 16;
+            }
+          while (x < xae);
+          *xc = z2;
+        }
+    }
+#else
+  for (; xb < xbe; xc0++)
+    {
+      if ((y = *xb++))
+        {
+          x = xa;
+          xc = xc0;
+          carry = 0;
+          do
+            {
+              z = *x++ * y + *xc + carry;
+              carry = z >> 16;
+              *xc++ = z & 0xffff;
+            }
+          while (x < xae);
+          *xc = carry;
+        }
+    }
+#endif
+  for (xc0 = c->x, xc = xc0 + wc; wc > 0 && !*--xc; --wc);
+  c->wds = wc;
+  return c;
+}
+
+static Bigint *p5s;
+
+static Bigint *pow5mult(Bigint * b, int k)
+{
+  Bigint *b1, *p5, *p51;
+  int i;
+  static int p05[3] = { 5, 25, 125 };
+
+  if ((i = k & 3))
+    b = multadd(b, p05[i - 1], 0);
+
+  if (!(k >>= 2))
+    {
+      return b;
+    }
+
+  if (!(p5 = p5s))
+    {
+      /* first time */
+      p5 = p5s = i2b(625);
+      p5->next = 0;
+    }
+
+  for (;;)
+    {
+      if (k & 1)
+        {
+          b1 = mult(b, p5);
+          Bfree(b);
+          b = b1;
+        }
+      if (!(k >>= 1))
+        {
+          break;
+        }
+
+      if (!(p51 = p5->next))
+        {
+          p51 = p5->next = mult(p5, p5);
+          p51->next = 0;
+        }
+      p5 = p51;
+    }
+  return b;
+}
+
+static Bigint *lshift(Bigint * b, int k)
+{
+  int i, k1, n, n1;
+  Bigint *b1;
+  unsigned long *x, *x1, *xe, z;
+
+#ifdef Pack_32
+  n = k >> 5;
+#else
+  n = k >> 4;
+#endif
+  k1 = b->k;
+  n1 = n + b->wds + 1;
+  for (i = b->maxwds; n1 > i; i <<= 1)
+    {
+      k1++;
+    }
+  b1 = Balloc(k1);
+  x1 = b1->x;
+  for (i = 0; i < n; i++)
+    {
+      *x1++ = 0;
+    }
+  x = b->x;
+  xe = x + b->wds;
+#ifdef Pack_32
+  if (k &= 0x1f)
+    {
+      k1 = 32 - k;
+      z = 0;
+      do
+        {
+          *x1++ = *x << k | z;
+          z = *x++ >> k1;
+        }
+      while (x < xe);
+      if ((*x1 = z))
+        {
+          ++n1;
+        }
+    }
+#else
+  if (k &= 0xf)
+    {
+      k1 = 16 - k;
+      z = 0;
+      do
+        {
+          *x1++ = ((*x << k) & 0xffff) | z;
+          z = *x++ >> k1;
+        }
+      while (x < xe);
+      if ((*x1 = z))
+        {
+          ++n1;
+        }
+    }
+#endif
+  else
+    do
+      {
+        *x1++ = *x++;
+      }
+    while (x < xe);
+  b1->wds = n1 - 1;
+  Bfree(b);
+  return b1;
+}
+
+static int cmp(Bigint * a, Bigint * b)
+{
+  unsigned long *xa, *xa0, *xb, *xb0;
+  int i, j;
+
+  i = a->wds;
+  j = b->wds;
+#ifdef CONFIG_DEBUG_LIB
+  if (i > 1 && !a->x[i - 1])
+   {
+    ldbg("cmp called with a->x[a->wds-1] == 0\n");
+   }
+  if (j > 1 && !b->x[j - 1])
+   {
+    ldbg("cmp called with b->x[b->wds-1] == 0\n");
+   }
+#endif
+  if (i -= j)
+    return i;
+  xa0 = a->x;
+  xa = xa0 + j;
+  xb0 = b->x;
+  xb = xb0 + j;
+  for (;;)
+    {
+      if (*--xa != *--xb)
+        return *xa < *xb ? -1 : 1;
+      if (xa <= xa0)
+        break;
+    }
+  return 0;
+}
+
+static Bigint *diff(Bigint * a, Bigint * b)
+{
+  Bigint *c;
+  int i, wa, wb;
+  long borrow, y;               /* We need signed shifts here. */
+  unsigned long *xa, *xae, *xb, *xbe, *xc;
+#ifdef Pack_32
+  int32_t z;
+#endif
+
+  i = cmp(a, b);
+  if (!i)
+    {
+      c = Balloc(0);
+      c->wds = 1;
+      c->x[0] = 0;
+      return c;
+    }
+  if (i < 0)
+    {
+      c = a;
+      a = b;
+      b = c;
+      i = 1;
+    }
+  else
+    i = 0;
+  c = Balloc(a->k);
+  c->sign = i;
+  wa = a->wds;
+  xa = a->x;
+  xae = xa + wa;
+  wb = b->wds;
+  xb = b->x;
+  xbe = xb + wb;
+  xc = c->x;
+  borrow = 0;
+#ifdef Pack_32
+  do
+    {
+      y = (*xa & 0xffff) - (*xb & 0xffff) + borrow;
+      borrow = y >> 16;
+      Sign_Extend(borrow, y);
+      z = (*xa++ >> 16) - (*xb++ >> 16) + borrow;
+      borrow = z >> 16;
+      Sign_Extend(borrow, z);
+      Storeinc(xc, z, y);
+    }
+  while (xb < xbe);
+  while (xa < xae)
+    {
+      y = (*xa & 0xffff) + borrow;
+      borrow = y >> 16;
+      Sign_Extend(borrow, y);
+      z = (*xa++ >> 16) + borrow;
+      borrow = z >> 16;
+      Sign_Extend(borrow, z);
+      Storeinc(xc, z, y);
+    }
+#else
+  do
+    {
+      y = *xa++ - *xb++ + borrow;
+      borrow = y >> 16;
+      Sign_Extend(borrow, y);
+      *xc++ = y & 0xffff;
+    }
+  while (xb < xbe);
+  while (xa < xae)
+    {
+      y = *xa++ + borrow;
+      borrow = y >> 16;
+      Sign_Extend(borrow, y);
+      *xc++ = y & 0xffff;
+    }
+#endif
+  while (!*--xc)
+    wa--;
+  c->wds = wa;
+  return c;
+}
+
+static Bigint *d2b(double d, int *e, int *bits)
+{
+  Bigint *b;
+  int de, i, k;
+  unsigned long *x, y, z;
+
+#ifdef Pack_32
+  b = Balloc(1);
+#else
+  b = Balloc(2);
+#endif
+  x = b->x;
+
+  z = word0(d) & Frac_mask;
+  word0(d) &= 0x7fffffff;       /* clear sign bit, which we ignore */
+  if ((de = (int)(word0(d) >> Exp_shift)))
+    z |= Exp_msk1;
+#ifdef Pack_32
+  if ((y = word1(d)))
+    {
+      if ((k = lo0bits(&y)))
+        {
+          x[0] = y | z << (32 - k);
+          z >>= k;
+        }
+      else
+        x[0] = y;
+      i = b->wds = (x[1] = z) ? 2 : 1;
+    }
+  else
+    {
+#ifdef CONFIG_DEBUG_LIB
+      if (!z)
+        {
+          ldbg("Zero passed to d2b\n");
+        }
+#endif
+      k = lo0bits(&z);
+      x[0] = z;
+      i = b->wds = 1;
+      k += 32;
+    }
+#else
+  if ((y = word1(d)))
+    {
+      if ((k = lo0bits(&y)))
+        if (k >= 16)
+          {
+            x[0] = y | ((z << (32 - k)) & 0xffff);
+            x[1] = z >> (k - 16) & 0xffff;
+            x[2] = z >> k;
+            i = 2;
+          }
+        else
+          {
+            x[0] = y & 0xffff;
+            x[1] = (y >> 16) | ((z << (16 - k)) & 0xffff);
+            x[2] = z >> k & 0xffff;
+            x[3] = z >> (k + 16);
+            i = 3;
+          }
+      else
+        {
+          x[0] = y & 0xffff;
+          x[1] = y >> 16;
+          x[2] = z & 0xffff;
+          x[3] = z >> 16;
+          i = 3;
+        }
+    }
+  else
+    {
+#ifdef CONFIG_DEBUG_LIB
+      if (!z)
+        {
+          ldbg("Zero passed to d2b\n");
+        }
+#endif
+      k = lo0bits(&z);
+      if (k >= 16)
+        {
+          x[0] = z;
+          i = 0;
+        }
+      else
+        {
+          x[0] = z & 0xffff;
+          x[1] = z >> 16;
+          i = 1;
+        }
+      k += 32;
+    }
+  while (!x[i])
+    --i;
+  b->wds = i + 1;
+#endif
+  if (de)
+    {
+      *e = de - Bias - (P - 1) + k;
+      *bits = P - k;
+    }
+  else
+    {
+      *e = de - Bias - (P - 1) + 1 + k;
+#ifdef Pack_32
+      *bits = 32 * i - hi0bits(x[i - 1]);
+#else
+      *bits = (i + 2) * 16 - hi0bits(x[i]);
+#endif
+    }
+  return b;
+}
+
+static const double tens[] = {
+  1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
+  1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
+  1e20, 1e21, 1e22
+};
+
+#ifdef IEEE_Arith
+static const double bigtens[] = { 1e16, 1e32, 1e64, 1e128, 1e256 };
+static const double tinytens[] = { 1e-16, 1e-32, 1e-64, 1e-128, 1e-256 };
+
+#  define n_bigtens 5
+#else
+static const double bigtens[] = { 1e16, 1e32 };
+static const double tinytens[] = { 1e-16, 1e-32 };
+
+#  define n_bigtens 2
+#endif
+
+static int quorem(Bigint * b, Bigint * S)
+{
+  int n;
+  long borrow, y;
+  unsigned long carry, q, ys;
+  unsigned long *bx, *bxe, *sx, *sxe;
+#ifdef Pack_32
+  int32_t z;
+  uint32_t si, zs;
+#endif
+
+  n = S->wds;
+#ifdef CONFIG_DEBUG_LIB
+  if (b->wds > n)
+    {
+      ldbg("oversize b in quorem\n");
+    }
+#endif
+  if (b->wds < n)
+    {
+      return 0;
+    }
+  sx = S->x;
+  sxe = sx + --n;
+  bx = b->x;
+  bxe = bx + n;
+  q = *bxe / (*sxe + 1);        /* ensure q <= true quotient */
+#ifdef CONFIG_DEBUG_LIB
+  if (q > 9)
+   {
+     ldbg("oversized quotient in quorem\n");
+   }
+#endif
+  if (q)
+    {
+      borrow = 0;
+      carry = 0;
+      do
+        {
+#ifdef Pack_32
+          si = *sx++;
+          ys = (si & 0xffff) * q + carry;
+          zs = (si >> 16) * q + (ys >> 16);
+          carry = zs >> 16;
+          y = (*bx & 0xffff) - (ys & 0xffff) + borrow;
+          borrow = y >> 16;
+          Sign_Extend(borrow, y);
+          z = (*bx >> 16) - (zs & 0xffff) + borrow;
+          borrow = z >> 16;
+          Sign_Extend(borrow, z);
+          Storeinc(bx, z, y);
+#else
+          ys = *sx++ * q + carry;
+          carry = ys >> 16;
+          y = *bx - (ys & 0xffff) + borrow;
+          borrow = y >> 16;
+          Sign_Extend(borrow, y);
+          *bx++ = y & 0xffff;
+#endif
+        }
+      while (sx <= sxe);
+      if (!*bxe)
+        {
+          bx = b->x;
+          while (--bxe > bx && !*bxe)
+            --n;
+          b->wds = n;
+        }
+    }
+  if (cmp(b, S) >= 0)
+    {
+      q++;
+      borrow = 0;
+      carry = 0;
+      bx = b->x;
+      sx = S->x;
+      do
+        {
+#ifdef Pack_32
+          si = *sx++;
+          ys = (si & 0xffff) + carry;
+          zs = (si >> 16) + (ys >> 16);
+          carry = zs >> 16;
+          y = (*bx & 0xffff) - (ys & 0xffff) + borrow;
+          borrow = y >> 16;
+          Sign_Extend(borrow, y);
+          z = (*bx >> 16) - (zs & 0xffff) + borrow;
+          borrow = z >> 16;
+          Sign_Extend(borrow, z);
+          Storeinc(bx, z, y);
+#else
+          ys = *sx++ + carry;
+          carry = ys >> 16;
+          y = *bx - (ys & 0xffff) + borrow;
+          borrow = y >> 16;
+          Sign_Extend(borrow, y);
+          *bx++ = y & 0xffff;
+#endif
+        }
+      while (sx <= sxe);
+      bx = b->x;
+      bxe = bx + n;
+      if (!*bxe)
+        {
+          while (--bxe > bx && !*bxe)
+            --n;
+          b->wds = n;
+        }
+    }
+  return q;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/* dtoa for IEEE arithmetic (dmg): convert double to ASCII string.
+ *
+ * Inspired by "How to Print Floating-Point Numbers Accurately" by
+ * Guy L. Steele, Jr. and Jon L. White [Proc. ACM SIGPLAN '90, pp. 92-101].
+ *
+ * Modifications:
+ *      1. Rather than iterating, we use a simple numeric overestimate
+ *         to determine k = floor(log10(d)).  We scale relevant
+ *         quantities using O(log2(k)) rather than O(k) multiplications.
+ *      2. For some modes > 2 (corresponding to ecvt and fcvt), we don't
+ *         try to generate digits strictly left to right.  Instead, we
+ *         compute with fewer bits and propagate the carry if necessary
+ *         when rounding the final digit up.  This is often faster.
+ *      3. Under the assumption that input will be rounded nearest,
+ *         mode 0 renders 1e23 as 1e23 rather than 9.999999999999999e22.
+ *         That is, we allow equality in stopping tests when the
+ *         round-nearest rule will give the same floating-point value
+ *         as would satisfaction of the stopping test with strict
+ *         inequality.
+ *      4. We remove common factors of powers of 2 from relevant
+ *         quantities.
+ *      5. When converting floating-point integers less than 1e16,
+ *         we use floating-point arithmetic rather than resorting
+ *         to multiple-precision integers.
+ *      6. When asked to produce fewer than 15 digits, we first try
+ *         to get by with floating-point arithmetic; we resort to
+ *         multiple-precision integer arithmetic only if we cannot
+ *         guarantee that the floating-point calculation has given
+ *         the correctly rounded result.  For k requested digits and
+ *         "uniformly" distributed input, the probability is
+ *         something like 10^(k-15) that we must resort to the int32_t
+ *         calculation.
+ */
+
+char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
+{
+  /* Arguments ndigits, decpt, sign are similar to those of ecvt and fcvt;
+   * trailing zeros are suppressed from the returned string.  If not null, *rve 
+   * is set to point to the end of the return value.  If d is +-Infinity or
+   * NaN, then *decpt is set to 9999.
+   * 
+   * mode: 0 ==> shortest string that yields d when read in and rounded to
+   * nearest. 1 ==> like 0, but with Steele & White stopping rule; e.g. with
+   * IEEE P754 arithmetic , mode 0 gives 1e23 whereas mode 1 gives
+   * 9.999999999999999e22. 2 ==> max(1,ndigits) significant digits.  This gives 
+   * a return value similar to that of ecvt, except that trailing zeros are
+   * suppressed. 3 ==> through ndigits past the decimal point.  This gives a
+   * return value similar to that from fcvt, except that trailing zeros are
+   * suppressed, and ndigits can be negative. 4-9 should give the same return
+   * values as 2-3, i.e., 4 <= mode <= 9 ==> same return as mode 2 + (mode &
+   * 1).  These modes are mainly for debugging; often they run slower but
+   * sometimes faster than modes 2-3. 4,5,8,9 ==> left-to-right digit
+   * generation. 6-9 ==> don't try fast floating-point estimate (if
+   * applicable).
+   * 
+   * Values of mode other than 0-9 are treated as mode 0.
+   * 
+   * Sufficient space is allocated to the return value to hold the suppressed
+   * trailing zeros. */
+
+  int bbits, b2, b5, be, dig, i, ieps, ilim = 0, ilim0, ilim1 = 0,
+    j, j_1, k, k0, k_check, leftright, m2, m5, s2, s5, spec_case = 0, try_quick;
+  long L;
+  int denorm;
+  unsigned long x;
+  Bigint *b, *b1, *delta, *mlo = NULL, *mhi, *S;
+  double d2, ds, eps;
+  char *s, *s0;
+  static Bigint *result;
+  static int result_k;
+
+  if (result)
+    {
+      result->k = result_k;
+      result->maxwds = 1 << result_k;
+      Bfree(result);
+      result = 0;
+    }
+
+  if (word0(d) & Sign_bit)
+    {
+      /* set sign for everything, including 0's and NaNs */
+      *sign = 1;
+      word0(d) &= ~Sign_bit;    /* clear sign bit */
+    }
+  else
+    *sign = 0;
+
+#if defined(IEEE_Arith)
+#  ifdef IEEE_Arith
+  if ((word0(d) & Exp_mask) == Exp_mask)
+#else
+  if (word0(d) == 0x8000)
+#endif
+    {
+      /* Infinity or NaN */
+      *decpt = 9999;
+      s =
+#ifdef IEEE_Arith
+        !word1(d) && !(word0(d) & 0xfffff) ? "Infinity" :
+#endif
+        "NaN";
+      if (rve)
+        *rve =
+#ifdef IEEE_Arith
+          s[3] ? s + 8 :
+#endif
+          s + 3;
+      return s;
+    }
+#endif
+  if (!d)
+    {
+      *decpt = 1;
+      s = "0";
+      if (rve)
+        *rve = s + 1;
+      return s;
+    }
+
+  b = d2b(d, &be, &bbits);
+  if ((i = (int)(word0(d) >> Exp_shift1 & (Exp_mask >> Exp_shift1))))
+    {
+      d2 = d;
+      word0(d2) &= Frac_mask1;
+      word0(d2) |= Exp_11;
+
+      /* log(x) ~=~ log(1.5) + (x-1.5)/1.5 log10(x) = log(x) / log(10) ~=~
+       * log(1.5)/log(10) + (x-1.5)/(1.5*log(10)) log10(d) =
+       * (i-Bias)*log(2)/log(10) + log10(d2) This suggests computing an
+       * approximation k to log10(d) by k = (i - Bias)*0.301029995663981 + (
+       * (d2-1.5)*0.289529654602168 + 0.176091259055681 ); We want k to be too 
+       * large rather than too small. The error in the first-order Taylor
+       * series approximation is in our favor, so we just round up the constant 
+       * enough to compensate for any error in the multiplication of (i - Bias) 
+       * by 0.301029995663981; since |i - Bias| <= 1077, and 1077 * 0.30103 *
+       * 2^-52 ~=~ 7.2e-14, adding 1e-13 to the constant term more than
+       * suffices. Hence we adjust the constant term to 0.1760912590558. (We
+       * could get a more accurate k by invoking log10, but this is probably
+       * not worthwhile.) */
+
+      i -= Bias;
+      denorm = 0;
+    }
+  else
+    {
+      /* d is denormalized */
+
+      i = bbits + be + (Bias + (P - 1) - 1);
+      x = i > 32 ? word0(d) << (64 - i) | word1(d) >> (i - 32)
+        : word1(d) << (32 - i);
+      d2 = x;
+      word0(d2) -= 31 * Exp_msk1;       /* adjust exponent */
+      i -= (Bias + (P - 1) - 1) + 1;
+      denorm = 1;
+    }
+  ds = (d2 - 1.5) * 0.289529654602168 + 0.1760912590558 + i * 0.301029995663981;
+  k = (int)ds;
+  if (ds < 0. && ds != k)
+    k--;                        /* want k = floor(ds) */
+  k_check = 1;
+  if (k >= 0 && k <= Ten_pmax)
+    {
+      if (d < tens[k])
+        k--;
+      k_check = 0;
+    }
+  j = bbits - i - 1;
+  if (j >= 0)
+    {
+      b2 = 0;
+      s2 = j;
+    }
+  else
+    {
+      b2 = -j;
+      s2 = 0;
+    }
+  if (k >= 0)
+    {
+      b5 = 0;
+      s5 = k;
+      s2 += k;
+    }
+  else
+    {
+      b2 -= k;
+      b5 = -k;
+      s5 = 0;
+    }
+  if (mode < 0 || mode > 9)
+    mode = 0;
+  try_quick = 1;
+  if (mode > 5)
+    {
+      mode -= 4;
+      try_quick = 0;
+    }
+  leftright = 1;
+  switch (mode)
+    {
+    case 0:
+    case 1:
+      ilim = ilim1 = -1;
+      i = 18;
+      ndigits = 0;
+      break;
+    case 2:
+      leftright = 0;
+      /* no break */
+    case 4:
+      if (ndigits <= 0)
+        ndigits = 1;
+      ilim = ilim1 = i = ndigits;
+      break;
+    case 3:
+      leftright = 0;
+      /* no break */
+    case 5:
+      i = ndigits + k + 1;
+      ilim = i;
+      ilim1 = i - 1;
+      if (i <= 0)
+        i = 1;
+    }
+  j = sizeof(unsigned long);
+  for (result_k = 0; (signed)(sizeof(Bigint) - sizeof(unsigned long) + j) <= i;
+       j <<= 1)
+    result_k++;
+  result = Balloc(result_k);
+  s = s0 = (char *)result;
+
+  if (ilim >= 0 && ilim <= Quick_max && try_quick)
+    {
+
+      /* Try to get by with floating-point arithmetic. */
+
+      i = 0;
+      d2 = d;
+      k0 = k;
+      ilim0 = ilim;
+      ieps = 2;                 /* conservative */
+      if (k > 0)
+        {
+          ds = tens[k & 0xf];
+          j = k >> 4;
+          if (j & Bletch)
+            {
+              /* prevent overflows */
+              j &= Bletch - 1;
+              d /= bigtens[n_bigtens - 1];
+              ieps++;
+            }
+          for (; j; j >>= 1, i++)
+            if (j & 1)
+              {
+                ieps++;
+                ds *= bigtens[i];
+              }
+          d /= ds;
+        }
+      else if ((j_1 = -k))
+        {
+          d *= tens[j_1 & 0xf];
+          for (j = j_1 >> 4; j; j >>= 1, i++)
+            if (j & 1)
+              {
+                ieps++;
+                d *= bigtens[i];
+              }
+        }
+      if (k_check && d < 1. && ilim > 0)
+        {
+          if (ilim1 <= 0)
+            goto fast_failed;
+          ilim = ilim1;
+          k--;
+          d *= 10.;
+          ieps++;
+        }
+      eps = ieps * d + 7.;
+      word0(eps) -= (P - 1) * Exp_msk1;
+      if (ilim == 0)
+        {
+          S = mhi = 0;
+          d -= 5.;
+          if (d > eps)
+            goto one_digit;
+          if (d < -eps)
+            goto no_digits;
+          goto fast_failed;
+        }
+#ifndef No_leftright
+      if (leftright)
+        {
+          /* Use Steele & White method of only generating digits needed. */
+          eps = 0.5 / tens[ilim - 1] - eps;
+          for (i = 0;;)
+            {
+              L = (int)d;
+              d -= L;
+              *s++ = '0' + (int)L;
+              if (d < eps)
+                goto ret1;
+              if (1. - d < eps)
+                goto bump_up;
+              if (++i >= ilim)
+                break;
+              eps *= 10.;
+              d *= 10.;
+            }
+        }
+      else
+        {
+#endif
+          /* Generate ilim digits, then fix them up. */
+          eps *= tens[ilim - 1];
+          for (i = 1;; i++, d *= 10.)
+            {
+              L = (int)d;
+              d -= L;
+              *s++ = '0' + (int)L;
+              if (i == ilim)
+                {
+                  if (d > 0.5 + eps)
+                    goto bump_up;
+                  else if (d < 0.5 - eps)
+                    {
+                      while (*--s == '0');
+                      s++;
+                      goto ret1;
+                    }
+                  break;
+                }
+            }
+#ifndef No_leftright
+        }
+#endif
+    fast_failed:
+      s = s0;
+      d = d2;
+      k = k0;
+      ilim = ilim0;
+    }
+
+  /* Do we have a "small" integer? */
+
+  if (be >= 0 && k <= Int_max)
+    {
+      /* Yes. */
+      ds = tens[k];
+      if (ndigits < 0 && ilim <= 0)
+        {
+          S = mhi = 0;
+          if (ilim < 0 || d <= 5 * ds)
+            goto no_digits;
+          goto one_digit;
+        }
+      for (i = 1;; i++)
+        {
+          L = (int)(d / ds);
+          d -= L * ds;
+#ifdef Check_FLT_ROUNDS
+          /* If FLT_ROUNDS == 2, L will usually be high by 1 */
+          if (d < 0)
+            {
+              L--;
+              d += ds;
+            }
+#endif
+          *s++ = '0' + (int)L;
+          if (i == ilim)
+            {
+              d += d;
+              if (d > ds || (d == ds && (L & 1)))
+                {
+                bump_up:
+                  while (*--s == '9')
+                    if (s == s0)
+                      {
+                        k++;
+                        *s = '0';
+                        break;
+                      }
+                  ++*s++;
+                }
+              break;
+            }
+          if (!(d *= 10.))
+            break;
+        }
+      goto ret1;
+    }
+
+  m2 = b2;
+  m5 = b5;
+  mhi = mlo = 0;
+  if (leftright)
+    {
+      if (mode < 2)
+        {
+          i = denorm ? be + (Bias + (P - 1) - 1 + 1) : 1 + P - bbits;
+        }
+      else
+        {
+          j = ilim - 1;
+          if (m5 >= j)
+            m5 -= j;
+          else
+            {
+              s5 += j -= m5;
+              b5 += j;
+              m5 = 0;
+            }
+          if ((i = ilim) < 0)
+            {
+              m2 -= i;
+              i = 0;
+            }
+        }
+      b2 += i;
+      s2 += i;
+      mhi = i2b(1);
+    }
+  if (m2 > 0 && s2 > 0)
+    {
+      i = m2 < s2 ? m2 : s2;
+      b2 -= i;
+      m2 -= i;
+      s2 -= i;
+    }
+  if (b5 > 0)
+    {
+      if (leftright)
+        {
+          if (m5 > 0)
+            {
+              mhi = pow5mult(mhi, m5);
+              b1 = mult(mhi, b);
+              Bfree(b);
+              b = b1;
+            }
+          if ((j = b5 - m5))
+            b = pow5mult(b, j);
+        }
+      else
+        b = pow5mult(b, b5);
+    }
+  S = i2b(1);
+  if (s5 > 0)
+    S = pow5mult(S, s5);
+
+  /* Check for special case that d is a normalized power of 2. */
+
+  if (mode < 2)
+    {
+      if (!word1(d) && !(word0(d) & Bndry_mask) && word0(d) & Exp_mask)
+        {
+          /* The special case */
+          b2 += Log2P;
+          s2 += Log2P;
+          spec_case = 1;
+        }
+      else
+        spec_case = 0;
+    }
+
+  /* 
+   * Arrange for convenient computation of quotients: shift left if
+   * necessary so divisor has 4 leading 0 bits.
+   *
+   * Perhaps we should just compute leading 28 bits of S once and for all
+   * and pass them and a shift to quorem, so it can do shifts and ors
+   * to compute the numerator for q.
+   */
+#ifdef Pack_32
+  if ((i = ((s5 ? 32 - hi0bits(S->x[S->wds - 1]) : 1) + s2) & 0x1f))
+    i = 32 - i;
+#else
+  if ((i = ((s5 ? 32 - hi0bits(S->x[S->wds - 1]) : 1) + s2) & 0xf))
+    i = 16 - i;
+#endif
+  if (i > 4)
+    {
+      i -= 4;
+      b2 += i;
+      m2 += i;
+      s2 += i;
+    }
+  else if (i < 4)
+    {
+      i += 28;
+      b2 += i;
+      m2 += i;
+      s2 += i;
+    }
+  if (b2 > 0)
+    b = lshift(b, b2);
+  if (s2 > 0)
+    S = lshift(S, s2);
+  if (k_check)
+    {
+      if (cmp(b, S) < 0)
+        {
+          k--;
+          b = multadd(b, 10, 0);        /* we botched the k estimate */
+          if (leftright)
+            mhi = multadd(mhi, 10, 0);
+          ilim = ilim1;
+        }
+    }
+  if (ilim <= 0 && mode > 2)
+    {
+      if (ilim < 0 || cmp(b, S = multadd(S, 5, 0)) <= 0)
+        {
+          /* no digits, fcvt style */
+        no_digits:
+          k = -1 - ndigits;
+          goto ret;
+        }
+    one_digit:
+      *s++ = '1';
+      k++;
+      goto ret;
+    }
+  if (leftright)
+    {
+      if (m2 > 0)
+        mhi = lshift(mhi, m2);
+
+      /* Compute mlo -- check for special case that d is a normalized power of
+       * 2. */
+
+      mlo = mhi;
+      if (spec_case)
+        {
+          mhi = Balloc(mhi->k);
+          Bcopy(mhi, mlo);
+          mhi = lshift(mhi, Log2P);
+        }
+
+      for (i = 1;; i++)
+        {
+          dig = quorem(b, S) + '0';
+          /* Do we yet have the shortest decimal string that will round to d? */
+          j = cmp(b, mlo);
+          delta = diff(S, mhi);
+          j_1 = delta->sign ? 1 : cmp(b, delta);
+          Bfree(delta);
+#ifndef ROUND_BIASED
+          if (j_1 == 0 && !mode && !(word1(d) & 1))
+            {
+              if (dig == '9')
+                goto round_9_up;
+              if (j > 0)
+                dig++;
+              *s++ = dig;
+              goto ret;
+            }
+#endif
+          if (j < 0 || (j == 0 && !mode
+#ifndef ROUND_BIASED
+                        && (!(word1(d) & 1)))
+#endif
+            )
+            {
+              if ((j_1 > 0))
+                {
+                  b = lshift(b, 1);
+                  j_1 = cmp(b, S);
+                  if ((j_1 > 0 || (j_1 == 0 && (dig & 1))) && dig++ == '9')
+                    goto round_9_up;
+                }
+              *s++ = dig;
+              goto ret;
+            }
+          if (j_1 > 0)
+            {
+              if (dig == '9')
+                {               /* possible if i == 1 */
+                round_9_up:
+                  *s++ = '9';
+                  goto roundoff;
+                }
+              *s++ = dig + 1;
+              goto ret;
+            }
+          *s++ = dig;
+          if (i == ilim)
+            break;
+          b = multadd(b, 10, 0);
+          if (mlo == mhi)
+            mlo = mhi = multadd(mhi, 10, 0);
+          else
+            {
+              mlo = multadd(mlo, 10, 0);
+              mhi = multadd(mhi, 10, 0);
+            }
+        }
+    }
+  else
+    for (i = 1;; i++)
+      {
+        *s++ = dig = quorem(b, S) + '0';
+        if (i >= ilim)
+          break;
+        b = multadd(b, 10, 0);
+      }
+
+  /* Round off last digit */
+
+  b = lshift(b, 1);
+  j = cmp(b, S);
+  if (j > 0 || (j == 0 && (dig & 1)))
+    {
+    roundoff:
+      while (*--s == '9')
+        if (s == s0)
+          {
+            k++;
+            *s++ = '1';
+            goto ret;
+          }
+      ++*s++;
+    }
+  else
+    {
+      while (*--s == '0');
+      s++;
+    }
+ret:
+  Bfree(S);
+  if (mhi)
+    {
+      if (mlo && mlo != mhi)
+        Bfree(mlo);
+      Bfree(mhi);
+    }
+ret1:
+  Bfree(b);
+  if (s == s0)
+    {                           /* don't return empty string */
+      *s++ = '0';
+      k = 0;
+    }
+  *s = 0;
+  *decpt = k + 1;
+  if (rve)
+    *rve = s;
+  return s0;
+}
diff --git a/nuttx/lib/lib_internal.h b/nuttx/lib/lib_internal.h
index 46af49cf4..6ec2fe201 100644
--- a/nuttx/lib/lib_internal.h
+++ b/nuttx/lib/lib_internal.h
@@ -1,7 +1,7 @@
 /****************************************************************************
  * lib/lib_internal.h
  *
- *   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2010 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -102,6 +102,13 @@ extern int lib_rawvprintf(const char *src, va_list ap);
 
 extern int lib_lowvprintf(const char *src, va_list ap);
 
+/* Defined in lib_dtoa.c */
+
+#ifdef CONFIG_LIBC_FLOATINGPOINT
+extern char *__dtoa(double d, int mode, int ndigits,
+                    int *decpt, int *sign, char **rve);
+#endif
+
 /* Defined in lib_libwrite.c */
 
 extern ssize_t lib_fwrite(FAR const void *ptr, size_t count, FAR FILE *stream);
diff --git a/nuttx/lib/lib_libdtoa.c b/nuttx/lib/lib_libdtoa.c
new file mode 100755
index 000000000..1f74247c2
--- /dev/null
+++ b/nuttx/lib/lib_libdtoa.c
@@ -0,0 +1,365 @@
+/****************************************************************************
+ * lib/lib_libdtoa.c
+ *
+ * This file was ported to NuttX by Yolande Cates.
+ *
+ * Copyright (c) 1990, 1993
+ *      The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * 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. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by the University of
+ *      California, Berkeley and its contributors.
+ * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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
+ ****************************************************************************/
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define MAXEXP 308
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static char* cvt(double value, int ndigits, int flags, char *sign,
+                 int *decpt, int ch, int *length);
+static int   exponent(char *p0, int exp, int fmtch);
+
+/****************************************************************************
+ * Global Constant Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Constant Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: cvt
+ ****************************************************************************/
+
+static char* cvt(double value, int ndigits, int flags, char *sign,
+                 int *decpt, int ch, int *length)
+{
+  int mode, dsgn;
+  char *digits, *bp, *rve;
+
+  if (ch == 'f')
+    {
+      mode = 3;               /* ndigits after the decimal point */
+    }
+  else
+    {
+      /* To obtain ndigits after the decimal point for the 'e' and 'E'
+       * formats, round to ndigits + 1 significant figures.
+       */
+
+      if (ch == 'e' || ch == 'E')
+        {
+          ndigits++;
+        }
+      mode = 2;               /* ndigits significant digits */
+    }
+
+  if (value < 0)
+    {
+      value = -value;
+      *sign = '-';
+    }
+  else
+    {
+      *sign = '\000';
+    }
+
+  digits = __dtoa(value, mode, ndigits, decpt, &dsgn, &rve);
+  if ((ch != 'g' && ch != 'G') || IS_ALTFORM(flags))
+    {
+      /* Print trailing zeros */
+
+      bp = digits + ndigits;
+      if (ch == 'f')
+        {
+          if (*digits == '0' && value)
+            {
+              *decpt = -ndigits + 1;
+            }
+          bp += *decpt;
+        }
+
+      if (value == 0)
+        {
+	  /* kludge for __dtoa irregularity */
+
+          rve = bp;
+        }
+
+      while (rve < bp)
+        {
+          *rve++ = '0';
+        }
+    }
+
+  *length = rve - digits;
+  return digits;
+}
+
+/****************************************************************************
+ * Name: exponent
+ ****************************************************************************/
+
+static int exponent(FAR char *p0, int exp, int fmtch)
+{
+  FAR char *p;
+  FAR char *t;
+  char expbuf[MAXEXP];
+
+  p = p0;
+  *p++ = fmtch;
+  if (exp < 0)
+    {
+      exp = -exp;
+      *p++ = '-';
+    }
+  else
+    {
+      *p++ = '+';
+    }
+
+  t = expbuf + MAXEXP;
+  if (exp > 9)
+    {
+      do
+        {
+          *--t = (exp % 10) + '0';
+        }
+      while ((exp /= 10) > 9);
+      *--t = exp + '0';
+      for (; t < expbuf + MAXEXP; *p++ = *t++);
+    }
+  else
+    {
+      *p++ = '0';
+      *p++ = exp + '0';
+    }
+  return (p - p0);
+}
+
+/****************************************************************************
+ * Name: lib_dtoa
+ *
+ * Description:
+ *   This is part of lib_vsprintf().  It handles the floating point formats.
+ *
+ ****************************************************************************/
+
+static void lib_dtoa(FAR struct lib_outstream_s *obj, int ch, int prec,
+                     uint8_t flags, double _double)
+{
+  FAR char *cp;              /* Handy char pointer (short term usage) */
+  FAR char *cp_free = NULL;  /* BIONIC: copy of cp to be freed after usage */
+  char expstr[7];            /* Buffer for exponent string */
+  char sign;                 /* Temporary negative sign for floats */
+  int  expt;                 /* Integer value of exponent */
+  int  expsize = 0;          /* Character count for expstr */
+  int  ndig;                 /* Actual number of digits returned by cvt */
+  int  size;                 /* Size of converted field or string */
+  int  i;
+
+  cp = cvt(_double, prec, flags, &sign, &expt, ch, &ndig);
+  cp_free = cp;
+
+  if (ch == 'g' || ch == 'G')
+    {
+      /* 'g' or 'G' fmt */
+
+      if (expt <= -4 || expt > prec)
+        {
+          ch = (ch == 'g') ? 'e' : 'E';
+        }
+      else
+        {
+          ch = 'g';
+        }
+    }
+
+  if (ch <= 'e')
+    {
+      /* 'e' or 'E' fmt */
+
+      --expt;
+      expsize = exponent(expstr, expt, ch);
+      size = expsize + ndig;
+      if (ndig > 1 || IS_ALTFORM(flags))
+        {
+          ++size;
+        }
+    }
+  else if (ch == 'f')
+    {
+      /* f fmt */
+
+      if (expt > 0)
+        {
+          size = expt;
+          if (prec || IS_ALTFORM(flags))
+            {
+              size += prec + 1;
+            }
+        }
+      else  /* "0.X" */
+        {
+            size = prec + 2;
+        }
+    }
+  else if (expt >= ndig)
+    {
+      /* fixed g fmt */
+
+      size = expt;
+      if (IS_ALTFORM(flags))
+        {
+          ++size;
+        }
+    }
+  else
+    {
+      size = ndig + (expt > 0 ? 1 : 2 - expt);
+    }
+
+  if (sign)
+    {
+      obj->put(obj, '-');
+    }
+
+  if (_double == 0)
+    {
+      /* kludge for __dtoa irregularity */
+
+      obj->put(obj, '0');
+      if (expt < ndig || IS_ALTFORM(flags))
+        {
+          obj->put(obj, '.');
+
+          i = ndig - 1;
+          while (i > 0)
+            {
+              obj->put(obj, '0');
+              i--;
+            }
+        }
+    }
+  else if (expt <= 0)
+    {
+      obj->put(obj, '0');
+      obj->put(obj, '.');
+
+      i = ndig;
+      while (i > 0)
+        {
+          obj->put(obj, *cp);
+          i--;
+          cp++;
+        }
+    }
+  else if (expt >= ndig)
+    {
+      i = ndig;
+      while (i > 0)
+        {
+          obj->put(obj, *cp);
+          i--;
+          cp++;
+        }
+
+      i = expt - ndig;
+      while (i > 0)
+        {
+          obj->put(obj, '0');
+          i--;
+        }
+
+      if (IS_ALTFORM(flags))
+        {
+          obj->put(obj, '.');
+        }
+    }
+  else
+    {
+      /* print the integer */
+
+      i = expt;
+      while (i > 0)
+        {
+          obj->put(obj, *cp);
+          i--;
+          cp++;
+        }
+
+      /* print the decimal place */
+
+      obj->put(obj, '.');
+
+      /* print the decimal */
+
+      i = ndig - expt;
+      while (i > 0)
+        {
+          obj->put(obj, *cp);
+          i--;
+          cp++;
+        }
+    }
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
diff --git a/nuttx/lib/lib_libvsprintf.c b/nuttx/lib/lib_libvsprintf.c
index 1d28c1a6c..7ad2184eb 100644
--- a/nuttx/lib/lib_libvsprintf.c
+++ b/nuttx/lib/lib_libvsprintf.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * lib/lib_libvsprintf.c
  *
- *   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2010 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -186,6 +186,12 @@ static const char g_nullstring[] = "(null)";
  * Private Functions
  ****************************************************************************/
 
+/* Include floating point functions */
+ 
+#ifdef CONFIG_LIBC_FLOATINGPOINT
+#  include "lib_libdtoa.c"
+#endif
+
 /****************************************************************************
  * Name: ptohex
  ****************************************************************************/
@@ -1468,9 +1474,8 @@ int lib_vsprintf(FAR struct lib_outstream_s *obj, const char *src, va_list ap)
 #ifdef CONFIG_LIBC_FLOATINGPOINT
       else if (strchr("eEfgG", *src))
         {
-#ifdef CONFIG_CPP_HAVE_WARNING
-#  warning "No floating point support"
-#endif
+          double dblval = va_arg(ap, double);
+          lib_dtoa(obj, *src, trunc, flags, dblval);
         }
 #endif
     }