diff --git a/libs/libc/stdio/lib_dtoa.c b/libs/libc/stdio/lib_dtoa.c
index cdef4af2b2d..be733dab51e 100644
--- a/libs/libc/stdio/lib_dtoa.c
+++ b/libs/libc/stdio/lib_dtoa.c
@@ -54,154 +54,180 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-#ifdef Unsigned_Shifts
-#  define Sign_Extend(a,b) if (b < 0) a |= 0xffff0000;
+#ifdef CONFIG_DTOA_UNSIGNED_SHIFTS
+#  define SIGN_EXTEND(a,b) if (b < 0) a |= 0xffff0000;
 #else
-#  define Sign_Extend(a,b)      /* no-op */
+#  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]
+#  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]
+#  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, \
+#  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, \
+#  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 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 SMALL_MAX   14
+#define INFINITE(x) (WORD0(x) == 0x7ff00000)    /* sufficient test for here */
 
-#define Kmax 15
+#define KMAX        15
 
-#define Bcopy(x,y) memcpy((char *)&x->sign, (char *)&y->sign, \
-                          y->wds*sizeof(long) + 2*sizeof(int))
+#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_s
 {
-  struct Bigint *next;
-  int k, maxwds, sign, wds;
+  FAR struct bigint_s *next;
+  int k;
+  int maxwds;
+  int sign;
+  int wds;
   unsigned long x[1];
 };
 
-typedef struct Bigint Bigint;
+typedef struct bigint_s bigint_t;
 
 /****************************************************************************
  * Private Data
  ****************************************************************************/
 
-static Bigint *freelist[Kmax + 1];
+static FAR bigint_t *g_freelist[KMAX + 1];
+static FAR bigint_t *g_p5s;
+
+#ifdef IEEE_ARITH
+static const double g_bigtens[] =
+{
+  1e16, 1e32, 1e64, 1e128, 1e256
+};
+
+#  define n_bigtens 5
+#else
+static const double g_bigtens[] =
+{
+  1e16, 1e32
+};
+
+#  define n_bigtens 2
+#endif
 
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
 
-static Bigint *Balloc(int k)
+static FAR bigint_t *balloc(int k)
 {
+  FAR bigint_t *rv;
   int x;
-  Bigint *rv;
 
-  if ((rv = freelist[k]))
+  if ((rv = g_freelist[k]))
     {
-      freelist[k] = rv->next;
+      g_freelist[k] = rv->next;
     }
   else
     {
-      x = 1 << k;
-      rv = (Bigint *)lib_malloc(sizeof(Bigint) + (x - 1) * sizeof(long));
-      rv->k = k;
-      rv->maxwds = x;
+      x           = 1 << k;
+      rv          = (FAR bigint_t *)
+                    lib_malloc(sizeof(bigint_t) + (x - 1) * sizeof(long));
+      rv->k       = k;
+      rv->maxwds  = x;
     }
 
-  rv->sign = rv->wds = 0;
+  rv->sign        = 0;
+  rv->wds         = 0;
   return rv;
 }
 
-static void Bfree(Bigint * v)
+static void bfree(FAR bigint_t *v)
 {
-  if (v)
+  if (v != NULL)
     {
-      v->next = freelist[v->k];
-      freelist[v->k] = v;
+      v->next        = g_freelist[v->k];
+      g_freelist[v->k] = v;
     }
 }
 
-/* multiply by m and add a */
+/* Multiply by m and add a */
 
-static Bigint *multadd(Bigint * b, int m, int a)
+static FAR bigint_t *multadd(FAR bigint_t *b, int m, int a)
 {
-  int i, wds;
-  unsigned long *x, y;
-#ifdef Pack_32
-  unsigned long xi, z;
+  FAR bigint_t *b1;
+  FAR unsigned long *x;
+  unsigned long y;
+#ifdef CONFIG_DTOA_PACK32
+  unsigned long xi;
+  unsigned long z;
 #endif
-  Bigint *b1;
+  int wds;
+  int i;
 
   wds = b->wds;
-  x = b->x;
-  i = 0;
+  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);
+#ifdef CONFIG_DTOA_PACK32
+      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);
+      y    = *x * m + a;
+      a    = (int)(y >> 16);
       *x++ = y & 0xffff;
 #endif
     }
   while (++i < wds);
 
-  if (a)
+  if (a != 0)
     {
       if (wds >= b->maxwds)
         {
-          b1 = Balloc(b->k + 1);
-          Bcopy(b1, b);
-          Bfree(b);
-          b = b1;
+          b1 = balloc(b->k + 1);
+          BCOPY(b1, b);
+          bfree(b);
+          b  = b1;
         }
       b->x[wds++] = a;
-      b->wds = wds;
+      b->wds      = wds;
     }
 
   return b;
@@ -211,34 +237,34 @@ static int hi0bits(unsigned long x)
 {
   int k = 0;
 
-  if (!(x & 0xffff0000))
+  if ((x & 0xffff0000) == 0)
     {
-      k = 16;
+      k   = 16;
       x <<= 16;
     }
 
-  if (!(x & 0xff000000))
+  if ((x & 0xff000000) == 0)
     {
-      k += 8;
+      k  += 8;
       x <<= 8;
     }
 
-  if (!(x & 0xf0000000))
+  if ((x & 0xf0000000) == 0)
     {
-      k += 4;
+      k  += 4;
       x <<= 4;
     }
 
-  if (!(x & 0xc0000000))
+  if ((x & 0xc0000000) == 0)
     {
-      k += 2;
+      k  += 2;
       x <<= 2;
     }
 
-  if (!(x & 0x80000000))
+  if ((x & 0x80000000) == 0)
     {
       k++;
-      if (!(x & 0x40000000))
+      if ((x & 0x40000000) == 0)
         {
           return 32;
         }
@@ -247,19 +273,19 @@ static int hi0bits(unsigned long x)
   return k;
 }
 
-static int lo0bits(unsigned long *y)
+static int lo0bits(FAR unsigned long *y)
 {
-  int k;
   unsigned long x = *y;
+  int k;
 
-  if (x & 7)
+  if ((x & 7) != 0)
     {
       if (x & 1)
         {
           return 0;
         }
 
-      if (x & 2)
+      if ((x & 2) != 0)
         {
           *y = x >> 1;
           return 1;
@@ -270,35 +296,35 @@ static int lo0bits(unsigned long *y)
     }
 
   k = 0;
-  if (!(x & 0xffff))
+  if ((x & 0xffff) == 0)
     {
-      k = 16;
+      k   = 16;
       x >>= 16;
     }
 
-  if (!(x & 0xff))
+  if ((x & 0xff) == 0)
     {
-      k += 8;
+      k  += 8;
       x >>= 8;
     }
 
-  if (!(x & 0xf))
+  if ((x & 0xf) == 0)
     {
-      k += 4;
+      k  += 4;
       x >>= 4;
     }
 
-  if (!(x & 0x3))
+  if ((x & 0x3) == 0)
     {
-      k += 2;
+      k  += 2;
       x >>= 2;
     }
 
-  if (!(x & 1))
+  if ((x & 1) == 0)
     {
       k++;
       x >>= 1;
-      if (!x & 1)
+      if ((!x & 1) != 0)
         {
           return 32;
         }
@@ -308,25 +334,36 @@ static int lo0bits(unsigned long *y)
   return k;
 }
 
-static Bigint *i2b(int i)
+static FAR bigint_t *i2b(int i)
 {
-  Bigint *b;
+  FAR bigint_t *b;
 
-  b = Balloc(1);
+  b       = balloc(1);
   b->x[0] = i;
-  b->wds = 1;
+  b->wds  = 1;
   return b;
 }
 
-static Bigint *mult(Bigint * a, Bigint * b)
+static FAR bigint_t *mult(FAR bigint_t *a, FAR bigint_t *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
+  FAR bigint_t *c;
+  FAR unsigned long *x;
+  FAR unsigned long *xa;
+  FAR unsigned long *xae;
+  FAR unsigned long *xb;
+  FAR unsigned long *xbe;
+  FAR unsigned long *xc;
+  FAR unsigned long *xc0;
+  unsigned long carry;
+  unsigned long y;
+  unsigned long z;
+#ifdef CONFIG_DTOA_PACK32
   uint32_t z2;
 #endif
+  int k;
+  int wa;
+  int wb;
+  int wc;
 
   if (a->wds < b->wds)
     {
@@ -335,41 +372,44 @@ static Bigint *mult(Bigint * a, Bigint * b)
       b = c;
     }
 
-  k = a->k;
+  k  = a->k;
   wa = a->wds;
   wb = b->wds;
   wc = wa + wb;
+
   if (wc > a->maxwds)
     {
       k++;
     }
 
-  c = Balloc(k);
+  c = balloc(k);
   for (x = c->x, xa = x + wc; x < xa; x++)
     {
       *x = 0;
     }
 
-  xa = a->x;
+  xa  = a->x;
   xae = xa + wa;
-  xb = b->x;
+  xb  = b->x;
   xbe = xb + wb;
   xc0 = c->x;
-#ifdef Pack_32
+
+#ifdef CONFIG_DTOA_PACK32
   for (; xb < xbe; xb++, xc0++)
     {
-      if ((y = *xb & 0xffff))
+      if ((y = *xb & 0xffff) != 0)
         {
-          x = xa;
-          xc = xc0;
+          x     = xa;
+          xc    = xc0;
           carry = 0;
+
           do
             {
-              z = (*x & 0xffff) * y + (*xc & 0xffff) + carry;
+              z     = (*x & 0xffff) * y + (*xc & 0xffff) + carry;
               carry = z >> 16;
-              z2 = (*x++ >> 16) * y + (*xc >> 16) + carry;
+              z2    = (*x++ >> 16) * y + (*xc >> 16) + carry;
               carry = z2 >> 16;
-              Storeinc(xc, z2, z);
+              STOREINC(xc, z2, z);
             }
           while (x < xae);
 
@@ -378,16 +418,17 @@ static Bigint *mult(Bigint * a, Bigint * b)
 
       if ((y = *xb >> 16))
         {
-          x = xa;
-          xc = xc0;
+          x     = xa;
+          xc    = xc0;
           carry = 0;
-          z2 = *xc;
+          z2    = *xc;
+
           do
             {
-              z = (*x & 0xffff) * y + (*xc >> 16) + carry;
+              z     = (*x & 0xffff) * y + (*xc >> 16) + carry;
               carry = z >> 16;
-              Storeinc(xc, z, z2);
-              z2 = (*x++ >> 16) * y + (*xc & 0xffff) + carry;
+              STOREINC(xc, z, z2);
+              z2    = (*x++ >> 16) * y + (*xc & 0xffff) + carry;
               carry = z2 >> 16;
             }
           while (x < xae);
@@ -400,12 +441,13 @@ static Bigint *mult(Bigint * a, Bigint * b)
     {
       if ((y = *xb++))
         {
-          x = xa;
-          xc = xc0;
+          x     = xa;
+          xc    = xc0;
           carry = 0;
+
           do
             {
-              z = *x++ * y + *xc + carry;
+              z     = *x++ * y + *xc + carry;
               carry = z >> 16;
               *xc++ = z & 0xffff;
             }
@@ -416,54 +458,59 @@ static Bigint *mult(Bigint * a, Bigint * b)
     }
 #endif
 
-  for (xc0 = c->x, xc = xc0 + wc; wc > 0 && !*--xc; --wc);
+  for (xc0 = c->x, xc = xc0 + wc; wc > 0 && *--xc == 0; --wc);
   c->wds = wc;
   return c;
 }
 
-static Bigint *p5s;
-
-static Bigint *pow5mult(Bigint * b, int k)
+static FAR bigint_t *pow5mult(FAR bigint_t *b, int k)
 {
-  Bigint *b1, *p5, *p51;
-  int i;
+  FAR bigint_t *b1;
+  FAR bigint_t *p5;
+  FAR bigint_t *p51;
   static int p05[3] =
   {
     5, 25, 125
   };
+  int i;
 
-  if ((i = k & 3))
-    b = multadd(b, p05[i - 1], 0);
+  if ((i = k & 3) != 0)
+    {
+      b = multadd(b, p05[i - 1], 0);
+    }
 
-  if (!(k >>= 2))
+  if ((k >>= 2) == 0)
     {
       return b;
     }
 
-  if (!(p5 = p5s))
+  if ((p5 = g_p5s) == 0)
     {
-      /* first time */
-      p5 = p5s = i2b(625);
+      /* First time */
+
+      g_p5s    = i2b(625);
+      p5       = g_p5s;
       p5->next = 0;
     }
 
   for (; ; )
     {
-      if (k & 1)
+      if ((k & 1) != 0)
         {
           b1 = mult(b, p5);
-          Bfree(b);
-          b = b1;
+          bfree(b);
+          b  = b1;
         }
 
-      if (!(k >>= 1))
+      if ((k >>= 1) == 0)
         {
           break;
         }
 
-      if (!(p51 = p5->next))
+      if ((p51 = p5->next) == 0)
         {
-          p51 = p5->next = mult(p5, p5);
+          p5->next  = mult(p5, p5);
+          p51       = p5->next;
           p51->next = 0;
         }
 
@@ -473,63 +520,74 @@ static Bigint *pow5mult(Bigint * b, int k)
   return b;
 }
 
-static Bigint *lshift(Bigint * b, int k)
+static FAR bigint_t *lshift(FAR bigint_t *b, int k)
 {
-  int i, k1, n, n1;
-  Bigint *b1;
-  unsigned long *x, *x1, *xe, z;
+  FAR bigint_t *b1;
+  FAR unsigned long *x;
+  FAR unsigned long *x1;
+  FAR unsigned long *xe;
+  unsigned long z;
+  int i;
+  int k1;
+  int n;
+  int n1;
 
-#ifdef Pack_32
+#ifdef CONFIG_DTOA_PACK32
   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);
+  b1 = balloc(k1);
   x1 = b1->x;
+
   for (i = 0; i < n; i++)
     {
       *x1++ = 0;
     }
 
-  x = b->x;
+  x  = b->x;
   xe = x + b->wds;
-#ifdef Pack_32
-  if (k &= 0x1f)
+
+#ifdef CONFIG_DTOA_PACK32
+  if ((k &= 0x1f) != 0)
     {
       k1 = 32 - k;
-      z = 0;
+      z   = 0;
+
       do
         {
           *x1++ = *x << k | z;
-          z = *x++ >> k1;
+          z     = *x++ >> k1;
         }
       while (x < xe);
 
-      if ((*x1 = z))
+      if ((*x1 = z) != 0)
         {
           ++n1;
         }
     }
 #else
-  if (k &= 0xf)
+  if ((k &= 0xf) != 0)
     {
       k1 = 16 - k;
-      z = 0;
+      z   = 0;
+
       do
         {
           *x1++ = ((*x << k) & 0xffff) | z;
-          z = *x++ >> k1;
+          z     = *x++ >> k1;
         }
       while (x < xe);
 
-      if ((*x1 = z))
+      if ((*x1 = z) != 0)
         {
           ++n1;
         }
@@ -545,25 +603,29 @@ static Bigint *lshift(Bigint * b, int k)
     }
 
   b1->wds = n1 - 1;
-  Bfree(b);
+  bfree(b);
   return b1;
 }
 
-static int cmp(Bigint * a, Bigint * b)
+static int cmp(FAR bigint_t *a, FAR bigint_t *b)
 {
-  unsigned long *xa, *xa0, *xb, *xb0;
-  int i, j;
+  FAR unsigned long *xa;
+  FAR unsigned long *xa0;
+  FAR unsigned long *xb;
+  FAR unsigned long *xb0;
+  int i;
+  int j;
 
   i = a->wds;
   j = b->wds;
 
 #ifdef CONFIG_DEBUG_LIB
-  if (i > 1 && !a->x[i - 1])
+  if (i > 1 && a->x[i - 1] == 0)
    {
     lerr("ERROR: cmp called with a->x[a->wds-1] == 0\n");
    }
 
-  if (j > 1 && !b->x[j - 1])
+  if (j > 1 && b->x[j - 1] == 0)
    {
     lerr("ERROR: cmp called with b->x[b->wds-1] == 0\n");
    }
@@ -575,9 +637,9 @@ static int cmp(Bigint * a, Bigint * b)
     }
 
   xa0 = a->x;
-  xa = xa0 + j;
+  xa  = xa0 + j;
   xb0 = b->x;
-  xb = xb0 + j;
+  xb  = xb0 + j;
 
   for (; ; )
     {
@@ -595,21 +657,28 @@ static int cmp(Bigint * a, Bigint * b)
   return 0;
 }
 
-static Bigint *diff(Bigint * a, Bigint * b)
+static FAR bigint_t *diff(FAR bigint_t *a, FAR bigint_t *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
+  FAR bigint_t *c;
+  FAR unsigned long *xa;
+  FAR unsigned long *xae;
+  FAR unsigned long *xb;
+  FAR unsigned long *xbe;
+  FAR unsigned long *xc;
+  long borrow;                  /* We need signed shifts here. */
+  long y;
+#ifdef CONFIG_DTOA_PACK32
   int32_t z;
 #endif
+  int i;
+  int wa;
+  int wb;
 
   i = cmp(a, b);
-  if (!i)
+  if (i == 0)
     {
-      c = Balloc(0);
-      c->wds = 1;
+      c       = balloc(0);
+      c->wds  = 1;
       c->x[0] = 0;
       return c;
     }
@@ -626,59 +695,60 @@ static Bigint *diff(Bigint * a, Bigint * b)
       i = 0;
     }
 
-  c = Balloc(a->k);
+  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
+  wa      = a->wds;
+  xa      = a->x;
+  xae     = xa + wa;
+  wb      = b->wds;
+  xb      = b->x;
+  xbe     = xb + wb;
+  xc      = c->x;
+  borrow  = 0;
+
+#ifdef CONFIG_DTOA_PACK32
   do
     {
-      y = (*xa & 0xffff) - (*xb & 0xffff) + borrow;
+      y      = (*xa & 0xffff) - (*xb & 0xffff) + borrow;
       borrow = y >> 16;
-      Sign_Extend(borrow, y);
-      z = (*xa++ >> 16) - (*xb++ >> 16) + borrow;
+      SIGN_EXTEND(borrow, y);
+      z      = (*xa++ >> 16) - (*xb++ >> 16) + borrow;
       borrow = z >> 16;
-      Sign_Extend(borrow, z);
-      Storeinc(xc, z, y);
+      SIGN_EXTEND(borrow, z);
+      STOREINC(xc, z, y);
     }
   while (xb < xbe);
 
   while (xa < xae)
     {
-      y = (*xa & 0xffff) + borrow;
+      y      = (*xa & 0xffff) + borrow;
       borrow = y >> 16;
-      Sign_Extend(borrow, y);
-      z = (*xa++ >> 16) + borrow;
+      SIGN_EXTEND(borrow, y);
+      z      = (*xa++ >> 16) + borrow;
       borrow = z >> 16;
-      Sign_Extend(borrow, z);
-      Storeinc(xc, z, y);
+      SIGN_EXTEND(borrow, z);
+      STOREINC(xc, z, y);
     }
 #else
   do
     {
-      y = *xa++ - *xb++ + borrow;
+      y      = *xa++ - *xb++ + borrow;
       borrow = y >> 16;
-      Sign_Extend(borrow, y);
-      *xc++ = y & 0xffff;
+      SIGN_EXTEND(borrow, y);
+      *xc++  = y & 0xffff;
     }
   while (xb < xbe);
 
   while (xa < xae)
     {
-      y = *xa++ + borrow;
+      y      = *xa++ + borrow;
       borrow = y >> 16;
-      Sign_Extend(borrow, y);
-      *xc++ = y & 0xffff;
+      SIGN_EXTEND(borrow, y);
+      *xc++  = y & 0xffff;
     }
 #endif
 
-  while (!*--xc)
+  while (*--xc == 0)
     {
       wa--;
     }
@@ -687,61 +757,72 @@ static Bigint *diff(Bigint * a, Bigint * b)
   return c;
 }
 
-static Bigint *d2b(double d, int *e, int *bits)
+static FAR bigint_t *d2b(double d, int *e, int *bits)
 {
-  Bigint *b;
-  int de, i, k;
-  unsigned long *x, y, z;
+  FAR bigint_t *b;
+  FAR unsigned long *x;
+  unsigned long y;
+  unsigned long z;
+  int de;
+  int i;
+  int k;
 
-#ifdef Pack_32
-  b = Balloc(1);
+#ifdef CONFIG_DTOA_PACK32
+  b = balloc(1);
 #else
-  b = Balloc(2);
+  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)))
+  z         = WORD0(d) & FRAC_MASK;
+  WORD0(d) &= 0x7fffffff;       /* Clear sign bit, which we ignore */
+
+  de = (int)(WORD0(d) >> EXP_SHIFT);
+  if (de != 0)
     {
-      if ((k = lo0bits(&y)))
+      z |= EXP_MSK1;
+    }
+
+#ifdef CONFIG_DTOA_PACK32
+  if ((y = WORD1(d)) != 0)
+    {
+      if ((k = lo0bits(&y)) != 0)
         {
           x[0] = y | z << (32 - k);
-          z >>= k;
+          z  >>= k;
         }
       else
         {
           x[0] = y;
         }
 
-      i = b->wds = (x[1] = z) ? 2 : 1;
+      b->wds = (x[1] = z) ? 2 : 1;
+      i      = b->wds;
     }
   else
     {
 #ifdef CONFIG_DEBUG_LIB
-      if (!z)
+      if (z == 0)
         {
           lerr("ERROR: Zero passed to d2b\n");
         }
 #endif
-      k = lo0bits(&z);
+
+      k    = lo0bits(&z);
       x[0] = z;
-      i = b->wds = 1;
-      k += 32;
+      i    = b->wds = 1;
+      k   += 32;
     }
 #else
-  if ((y = word1(d)))
+  if ((y = WORD1(d)) != 0)
     {
-      if ((k = lo0bits(&y)))
+      if ((k = lo0bits(&y)) != 0)
         if (k >= 16)
           {
             x[0] = y | ((z << (32 - k)) & 0xffff);
             x[1] = z >> (k - 16) & 0xffff;
             x[2] = z >> k;
-            i = 2;
+            i    = 2;
           }
         else
           {
@@ -749,7 +830,7 @@ static Bigint *d2b(double d, int *e, int *bits)
             x[1] = (y >> 16) | ((z << (16 - k)) & 0xffff);
             x[2] = z >> k & 0xffff;
             x[3] = z >> (k + 16);
-            i = 3;
+            i    = 3;
           }
       else
         {
@@ -757,13 +838,13 @@ static Bigint *d2b(double d, int *e, int *bits)
           x[1] = y >> 16;
           x[2] = z & 0xffff;
           x[3] = z >> 16;
-          i = 3;
+          i    = 3;
         }
     }
   else
     {
 #ifdef CONFIG_DEBUG_LIB
-      if (!z)
+      if (z == 0)
         {
           lerr("ERROR: Zero passed to d2b\n");
         }
@@ -772,31 +853,34 @@ static Bigint *d2b(double d, int *e, int *bits)
       if (k >= 16)
         {
           x[0] = z;
-          i = 0;
+          i    = 0;
         }
       else
         {
           x[0] = z & 0xffff;
           x[1] = z >> 16;
-          i = 1;
+          i    = 1;
         }
 
       k += 32;
     }
+
   while (!x[i])
-    --i;
+    {
+      --i;
+    }
 
   b->wds = i + 1;
 #endif
-  if (de)
+  if (de != 0)
     {
-      *e = de - Bias - (P - 1) + k;
+      *e    = de - BIAS - (P - 1) + k;
       *bits = P - k;
     }
   else
     {
-      *e = de - Bias - (P - 1) + 1 + k;
-#ifdef Pack_32
+      *e    = de - BIAS - (P - 1) + 1 + k;
+#ifdef CONFIG_DTOA_PACK32
       *bits = 32 * i - hi0bits(x[i - 1]);
 #else
       *bits = (i + 2) * 16 - hi0bits(x[i]);
@@ -813,34 +897,25 @@ static const double tens[] =
   1e20, 1e21, 1e22
 };
 
-#ifdef IEEE_Arith
-static const double bigtens[] =
+static int quorem(FAR bigint_t *b, FAR bigint_t *s)
 {
-  1e16, 1e32, 1e64, 1e128, 1e256
-};
-
-#  define n_bigtens 5
-#else
-static const double bigtens[] =
-{
-  1e16, 1e32
-};
-
-#  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
+  long borrow;
+  long y;
+  unsigned long carry;
+  unsigned long q;
+  unsigned long ys;
+  FAR unsigned long *bx;
+  FAR unsigned long *bxe;
+  FAR unsigned long *sx;
+  FAR unsigned long *sxe;
+#ifdef CONFIG_DTOA_PACK32
   int32_t z;
-  uint32_t si, zs;
+  uint32_t si;
+  uint32_t zs;
 #endif
+  int n;
 
-  n = S->wds;
+  n = s->wds;
 
 #ifdef CONFIG_DEBUG_LIB
   if (b->wds > n)
@@ -854,11 +929,11 @@ static int quorem(Bigint * b, Bigint * S)
       return 0;
     }
 
-  sx = S->x;
+  sx   = s->x;
   sxe = sx + --n;
-  bx = b->x;
+  bx  = b->x;
   bxe = bx + n;
-  q = *bxe / (*sxe + 1);        /* ensure q <= true quotient */
+  q   = *bxe / (*sxe + 1);      /* ensure q <= true quotient */
 
 #ifdef CONFIG_DEBUG_LIB
   if (q > 9)
@@ -867,40 +942,40 @@ static int quorem(Bigint * b, Bigint * S)
     }
 #endif
 
-  if (q)
+  if (q != 0)
     {
       borrow = 0;
-      carry = 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;
+#ifdef CONFIG_DTOA_PACK32
+          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;
+          SIGN_EXTEND(borrow, y);
+          z      = (*bx >> 16) - (zs & 0xffff) + borrow;
           borrow = z >> 16;
-          Sign_Extend(borrow, z);
-          Storeinc(bx, z, y);
+          SIGN_EXTEND(borrow, z);
+          STOREINC(bx, z, y);
 #else
-          ys = *sx++ * q + carry;
-          carry = ys >> 16;
-          y = *bx - (ys & 0xffff) + borrow;
+          ys     = *sx++ * q + carry;
+          carry  = ys >> 16;
+          y      = *bx - (ys & 0xffff) + borrow;
           borrow = y >> 16;
-          Sign_Extend(borrow, y);
-          *bx++ = y & 0xffff;
+          SIGN_EXTEND(borrow, y);
+          *bx++  = y & 0xffff;
 #endif
         }
       while (sx <= sxe);
 
-      if (!*bxe)
+      if (*bxe == 0)
         {
           bx = b->x;
-          while (--bxe > bx && !*bxe)
+          while (--bxe > bx && *bxe == 0)
             {
               --n;
             }
@@ -909,45 +984,48 @@ static int quorem(Bigint * b, Bigint * S)
         }
     }
 
-  if (cmp(b, S) >= 0)
+  if (cmp(b, s) >= 0)
     {
       q++;
       borrow = 0;
-      carry = 0;
-      bx = b->x;
-      sx = S->x;
+      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;
+#ifdef CONFIG_DTOA_PACK32
+          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;
+          SIGN_EXTEND(borrow, y);
+          z      = (*bx >> 16) - (zs & 0xffff) + borrow;
           borrow = z >> 16;
-          Sign_Extend(borrow, z);
-          Storeinc(bx, z, y);
+          SIGN_EXTEND(borrow, z);
+          STOREINC(bx, z, y);
 #else
-          ys = *sx++ + carry;
-          carry = ys >> 16;
-          y = *bx - (ys & 0xffff) + borrow;
+          ys     = *sx++ + carry;
+          carry  = ys >> 16;
+          y      = *bx - (ys & 0xffff) + borrow;
           borrow = y >> 16;
-          Sign_Extend(borrow, y);
-          *bx++ = y & 0xffff;
+          SIGN_EXTEND(borrow, y);
+          *bx++  = y & 0xffff;
 #endif
         }
       while (sx <= sxe);
 
-      bx = b->x;
+      bx  = b->x;
       bxe = bx + n;
-      if (!*bxe)
+
+      if (*bxe == 0)
         {
-          while (--bxe > bx && !*bxe)
-            --n;
+          while (--bxe > bx && *bxe == 0)
+            {
+              --n;
+            }
 
           b->wds = n;
         }
@@ -994,153 +1072,192 @@ static int quorem(Bigint * b, Bigint * S)
  *         calculation.
  */
 
-char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
+FAR char *__dtoa(double d, int mode, int ndigits, FAR int *decpt,
+                 FAR int *sign, FAR 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.
+   * 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
+   * 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. */
+   * 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 FAR bigint_t *result;
   static int result_k;
+  FAR bigint_t *b;
+  FAR bigint_t *b1;
+  FAR bigint_t *delta;
+  FAR bigint_t *mlo = NULL;
+  FAR bigint_t *mhi;
+  FAR bigint_t *s;
+  FAR char *st;
+  FAR char *st0;
+  double d2;
+  double ds;
+  double eps;
+  long l;
+  unsigned long x;
+  int denorm;
+  int bbits;
+  int b2;
+  int b5;
+  int be;
+  int dig;
+  int i;
+  int ieps;
+  int ilim = 0;
+  int ilim0;
+  int ilim1 = 0;
+  int j;
+  int j_1;
+  int k;
+  int k0;
+  int k_check;
+  int leftright;
+  int m2;
+  int m5;
+  int s2;
+  int s5;
+  int spec_case = 0;
+  int try_quick;
 
-  if (result)
+  if (result != 0)
     {
-      result->k = result_k;
+      result->k      = result_k;
       result->maxwds = 1 << result_k;
-      Bfree(result);
-      result = 0;
+      bfree(result);
+      result         = 0;
     }
 
-  if (word0(d) & Sign_bit)
+  if ((WORD0(d) & SIGN_BIT) != 0)
     {
       /* Set sign for everything, including 0's and NaNs */
 
-      *sign = 1;
-      word0(d) &= ~Sign_bit;    /* clear sign bit */
+      *sign     = 1;
+      WORD0(d) &= ~SIGN_BIT;    /* clear sign bit */
     }
   else
     {
-      *sign = 0;
+      *sign     = 0;
     }
 
-#if defined(IEEE_Arith)
-#  ifdef IEEE_Arith
-  if ((word0(d) & Exp_mask) == Exp_mask)
+#if defined(IEEE_ARITH)
+#  ifdef IEEE_ARITH
+  if ((WORD0(d) & EXP_MASK) == EXP_MASK)
 #else
-  if (word0(d) == 0x8000)
+  if (WORD0(d) == 0x8000)
 #endif
     {
       /* Infinity or NaN */
 
       *decpt = 9999;
-      s =
-#ifdef IEEE_Arith
-        !word1(d) && !(word0(d) & 0xfffff) ? "Infinity" :
+      st =
+#ifdef IEEE_ARITH
+        !WORD1(d) && !(WORD0(d) & 0xfffff) ? "Infinity" :
 #endif
         "NaN";
-      if (rve)
+
+      if (rve != NULL)
         {
           *rve =
-#ifdef IEEE_Arith
-            s[3] ? s + 8 :
+#ifdef IEEE_ARITH
+            st[3] ? st + 8 :
 #endif
-            s + 3;
+            st + 3;
         }
 
-      return s;
+      return st;
     }
 #endif
 
-  if (!d)
+  if (d == 0)
     {
       *decpt = 1;
-      s = "0";
-      if (rve)
+      st = "0";
+
+      if (rve != NULL)
         {
-          *rve = s + 1;
+          *rve = st + 1;
         }
 
-      return s;
+      return st;
     }
 
   b = d2b(d, &be, &bbits);
-  if ((i = (int)(word0(d) >> Exp_shift1 & (Exp_mask >> Exp_shift1))))
+  i = (int)(WORD0(d) >> EXP_SHIFT1 & (EXP_MASK >> EXP_SHIFT1));
+  if (i != 0)
     {
-      d2 = d;
-      word0(d2) &= Frac_mask1;
-      word0(d2) |= Exp_11;
+      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)*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;
+      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;
+      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;
+  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--;  /* Want k = floor(ds) */
     }
 
   k_check = 1;
 
-  if (k >= 0 && k <= Ten_pmax)
+  if (k >= 0 && k <= TEN_PMAX)
     {
       if (d < tens[k])
-        k--;
+        {
+          k--;
+        }
+
       k_check = 0;
     }
 
@@ -1158,15 +1275,15 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 
   if (k >= 0)
     {
-      b5 = 0;
-      s5 = k;
+      b5  = 0;
+      s5  = k;
       s2 += k;
     }
   else
     {
       b2 -= k;
-      b5 = -k;
-      s5 = 0;
+      b5  = -k;
+      s5  = 0;
     }
 
   if (mode < 0 || mode > 9)
@@ -1177,7 +1294,7 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
   try_quick = 1;
   if (mode > 5)
     {
-      mode -= 4;
+      mode     -= 4;
       try_quick = 0;
     }
 
@@ -1193,23 +1310,30 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 
     case 2:
       leftright = 0;
+
       /* FALLTHROUGH */
+
     case 4:
       if (ndigits <= 0)
         {
           ndigits = 1;
         }
 
-      ilim = ilim1 = i = ndigits;
+      i     = ndigits;
+      ilim1 = i;
+      ilim  = i;
       break;
 
     case 3:
       leftright = 0;
+
       /* FALLTHROUGH */
+
     case 5:
-      i = ndigits + k + 1;
-      ilim = i;
+      i     = ndigits + k + 1;
+      ilim  = i;
       ilim1 = i - 1;
+
       if (i <= 0)
         {
           i = 1;
@@ -1218,36 +1342,37 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 
   j = sizeof(unsigned long);
   for (result_k = 0;
-       (signed)(sizeof(Bigint) - sizeof(unsigned long) + j) <= i;
+       (signed)(sizeof(bigint_t) - sizeof(unsigned long) + j) <= i;
        j <<= 1)
     {
       result_k++;
     }
 
-  result = Balloc(result_k);
-  s = s0 = (char *)result;
+  result = balloc(result_k);
+  st0    = (FAR char *)result;
+  st     = st0;
 
-  if (ilim >= 0 && ilim <= Quick_max && try_quick)
+  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 */
+      i      = 0;
+      d2     = d;
+      k0     = k;
+      ilim0  = ilim;
+      ieps   = 2;               /* Conservative */
 
       if (k > 0)
         {
           ds = tens[k & 0xf];
-          j = k >> 4;
+          j   = k >> 4;
 
-          if (j & Bletch)
+          if ((j & BLETCH) != 0)
             {
               /* Prevent overflows */
 
-              j &= Bletch - 1;
-              d /= bigtens[n_bigtens - 1];
+              j &= BLETCH - 1;
+              d /= g_bigtens[n_bigtens - 1];
               ieps++;
             }
 
@@ -1256,7 +1381,7 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
               if (j & 1)
                 {
                   ieps++;
-                  ds *= bigtens[i];
+                  ds *= g_bigtens[i];
                 }
             }
 
@@ -1267,10 +1392,10 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
           d *= tens[j_1 & 0xf];
           for (j = j_1 >> 4; j; j >>= 1, i++)
             {
-              if (j & 1)
+              if ((j & 1) != 0)
                 {
                   ieps++;
-                  d *= bigtens[i];
+                  d *= g_bigtens[i];
                 }
             }
         }
@@ -1284,26 +1409,33 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 
           ilim = ilim1;
           k--;
-          d *= 10.;
+          d   *= 10.;
           ieps++;
         }
 
-      eps = ieps * d + 7.;
-      word0(eps) -= (P - 1) * Exp_msk1;
+      eps         = ieps * d + 7.;
+      WORD0(eps) -= (P - 1) * EXP_MSK1;
+
       if (ilim == 0)
         {
-          S = mhi = 0;
-          d -= 5.;
+          mhi = 0;
+          s   = 0;
+          d  -= 5.;
+
           if (d > eps)
-            goto one_digit;
+            {
+              goto one_digit;
+            }
 
           if (d < -eps)
-            goto no_digits;
+            {
+              goto no_digits;
+            }
 
           goto fast_failed;
         }
 
-#ifndef No_leftright
+#ifndef CONFIG_DTOA_NO_LEFTRIGHT
       if (leftright)
         {
           /* Use Steele & White method of only generating digits needed. */
@@ -1311,9 +1443,10 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
           eps = 0.5 / tens[ilim - 1] - eps;
           for (i = 0; ; )
             {
-              L = (int)d;
-              d -= L;
-              *s++ = '0' + (int)L;
+              l     = (int)d;
+              d    -= l;
+              *st++ = '0' + (int)l;
+
               if (d < eps)
                 {
                   goto ret1;
@@ -1330,7 +1463,7 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
                 }
 
               eps *= 10.;
-              d *= 10.;
+              d   *= 10.;
             }
         }
       else
@@ -1341,9 +1474,10 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
           eps *= tens[ilim - 1];
           for (i = 1; ; i++, d *= 10.)
             {
-              L = (int)d;
-              d -= L;
-              *s++ = '0' + (int)L;
+              l     = (int)d;
+              d    -= l;
+              *st++ = '0' + (int)l;
+
               if (i == ilim)
                 {
                   if (d > 0.5 + eps)
@@ -1352,35 +1486,38 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
                     }
                   else if (d < 0.5 - eps)
                     {
-                      while (*--s == '0');
-                      s++;
+                      while (*--st == '0')
+                        {
+                        }
+
+                      st++;
                       goto ret1;
                     }
 
                   break;
                 }
             }
-#ifndef No_leftright
+#ifndef CONFIG_DTOA_NO_LEFTRIGHT
         }
 #endif
 
-    fast_failed:
-      s = s0;
-      d = d2;
-      k = k0;
+fast_failed:
+      st   = st0;
+      d    = d2;
+      k    = k0;
       ilim = ilim0;
     }
 
   /* Do we have a "small" integer? */
 
-  if (be >= 0 && k <= Int_max)
+  if (be >= 0 && k <= SMALL_MAX)
     {
       /* Yes. */
 
       ds = tens[k];
       if (ndigits < 0 && ilim <= 0)
         {
-          S = mhi = 0;
+          s = mhi = 0;
           if (ilim < 0 || d <= 5 * ds)
             {
               goto no_digits;
@@ -1391,40 +1528,42 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 
       for (i = 1; ; i++)
         {
-          L = (int)(d / ds);
-          d -= L * ds;
+          l  = (int)(d / ds);
+          d -= l * ds;
 
 #ifdef Check_FLT_ROUNDS
-          /* If FLT_ROUNDS == 2, L will usually be high by 1 */
+          /* If FLT_ROUNDS == 2, l will usually be high by 1 */
 
           if (d < 0)
             {
-              L--;
+              l--;
               d += ds;
             }
 #endif
-          *s++ = '0' + (int)L;
+          *st++ = '0' + (int)l;
           if (i == ilim)
             {
               d += d;
-              if (d > ds || (d == ds && (L & 1)))
+              if (d > ds || (d == ds && (l & 1)))
                 {
-                bump_up:
-                  while (*--s == '9')
-                    if (s == s0)
-                      {
-                        k++;
-                        *s = '0';
-                        break;
-                      }
+bump_up:
+                  while (*--st == '9')
+                    {
+                      if (st == st0)
+                        {
+                          k++;
+                          *st = '0';
+                          break;
+                        }
+                    }
 
-                  ++*s++;
+                  ++*st++;
                 }
 
               break;
             }
 
-          if (!(d *= 10.))
+          if ((d *= 10.) == 0)
             {
               break;
             }
@@ -1433,31 +1572,34 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
       goto ret1;
     }
 
-  m2 = b2;
-  m5 = b5;
+  m2  = b2;
+  m5  = b5;
   mhi = mlo = 0;
+
   if (leftright)
     {
       if (mode < 2)
         {
-          i = denorm ? be + (Bias + (P - 1) - 1 + 1) : 1 + P - bbits;
+          i = denorm ? be + (BIAS + (P - 1) - 1 + 1) : 1 + P - bbits;
         }
       else
         {
           j = ilim - 1;
           if (m5 >= j)
-            m5 -= j;
+            {
+              m5 -= j;
+            }
           else
             {
               s5 += j -= m5;
               b5 += j;
-              m5 = 0;
+              m5  = 0;
             }
 
           if ((i = ilim) < 0)
             {
               m2 -= i;
-              i = 0;
+              i   = 0;
             }
         }
 
@@ -1468,7 +1610,7 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 
   if (m2 > 0 && s2 > 0)
     {
-      i = m2 < s2 ? m2 : s2;
+      i   = m2 < s2 ? m2 : s2;
       b2 -= i;
       m2 -= i;
       s2 -= i;
@@ -1481,12 +1623,12 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
           if (m5 > 0)
             {
               mhi = pow5mult(mhi, m5);
-              b1 = mult(mhi, b);
-              Bfree(b);
-              b = b1;
+              b1  = mult(mhi, b);
+              bfree(b);
+              b   = b1;
             }
 
-          if ((j = b5 - m5))
+          if ((j = b5 - m5) != 0)
             {
               b = pow5mult(b, j);
             }
@@ -1497,22 +1639,23 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
         }
     }
 
-  S = i2b(1);
+  s = i2b(1);
   if (s5 > 0)
     {
-      S = pow5mult(S, s5);
+      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)
+      if (WORD1(d) == 0 && (WORD0(d) & BNDRY_MASK) == 0 &&
+          (WORD0(d) & EXP_MASK) != 0)
         {
           /* The special case */
 
-          b2 += Log2P;
-          s2 += Log2P;
+          b2       += LOG2P;
+          s2       += LOG2P;
           spec_case = 1;
         }
       else
@@ -1524,18 +1667,20 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
   /* 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
+   * 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))
+#ifdef CONFIG_DTOA_PACK32
+  i = ((s5 ? 32 - hi0bits(s->x[s->wds - 1]) : 1) + s2) & 0x1f;
+  if (i != 0)
     {
       i = 32 - i;
     }
 #else
-  if ((i = ((s5 ? 32 - hi0bits(S->x[S->wds - 1]) : 1) + s2) & 0xf))
+  i = ((s5 ? 32 - hi0bits(s->x[s->wds - 1]) : 1) + s2) & 0xf;
+  if (i != 0)
     {
       i = 16 - i;
     }
@@ -1543,14 +1688,14 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 
   if (i > 4)
     {
-      i -= 4;
+      i  -= 4;
       b2 += i;
       m2 += i;
       s2 += i;
     }
   else if (i < 4)
     {
-      i += 28;
+      i  += 28;
       b2 += i;
       m2 += i;
       s2 += i;
@@ -1563,12 +1708,12 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 
   if (s2 > 0)
     {
-      S = lshift(S, s2);
+      s = lshift(s, s2);
     }
 
   if (k_check)
     {
-      if (cmp(b, S) < 0)
+      if (cmp(b, s) < 0)
         {
           k--;
           b = multadd(b, 10, 0);        /* we botched the k estimate */
@@ -1583,17 +1728,17 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 
   if (ilim <= 0 && mode > 2)
     {
-      if (ilim < 0 || cmp(b, S = multadd(S, 5, 0)) <= 0)
+      if (ilim < 0 || cmp(b, s = multadd(s, 5, 0)) <= 0)
         {
           /* no digits, fcvt style */
 
-        no_digits:
+no_digits:
           k = -1 - ndigits;
           goto ret;
         }
 
-    one_digit:
-      *s++ = '1';
+one_digit:
+      *st++ = '1';
       k++;
       goto ret;
     }
@@ -1606,26 +1751,29 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
         }
 
       /* Compute mlo -- check for special case that d is a normalized power of
-       * 2. */
+       * 2.
+       */
 
       mlo = mhi;
       if (spec_case)
         {
-          mhi = Balloc(mhi->k);
-          Bcopy(mhi, mlo);
-          mhi = lshift(mhi, Log2P);
+          mhi = balloc(mhi->k);
+          BCOPY(mhi, mlo);
+          mhi = lshift(mhi, LOG2P);
         }
 
       for (i = 1; ; i++)
         {
-          dig = quorem(b, S) + '0';
+          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))
+
+          j     = cmp(b, mlo);
+          delta = diff(s, mhi);
+          j_1   = delta->sign ? 1 : cmp(b, delta);
+          bfree(delta);
+#ifndef CONFIG_DTOA_ROUND_BIASED
+          if (j_1 == 0 && !mode && !(WORD1(d) & 1))
             {
               if (dig == '9')
                 {
@@ -1637,27 +1785,28 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
                   dig++;
                 }
 
-              *s++ = dig;
+              *st++ = dig;
               goto ret;
             }
 #endif
           if (j < 0 || (j == 0 && !mode
-#ifndef ROUND_BIASED
-                        && (!(word1(d) & 1))
+#ifndef CONFIG_DTOA_ROUND_BIASED
+              && ((WORD1(d) & 1) == 0)
 #endif
             ))
             {
               if ((j_1 > 0))
                 {
-                  b = lshift(b, 1);
-                  j_1 = cmp(b, S);
+                  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;
+              *st++ = dig;
               goto ret;
             }
 
@@ -1665,18 +1814,18 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
             {
               if (dig == '9')
                 {
-                  /* possible if i == 1 */
+                  /* Possible if i == 1 */
 
                   round_9_up:
-                  *s++ = '9';
+                  *st++ = '9';
                   goto roundoff;
                 }
 
-              *s++ = dig + 1;
+              *st++ = dig + 1;
               goto ret;
             }
 
-          *s++ = dig;
+          *st++ = dig;
           if (i == ilim)
             {
               break;
@@ -1685,7 +1834,8 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
           b = multadd(b, 10, 0);
           if (mlo == mhi)
             {
-              mlo = mhi = multadd(mhi, 10, 0);
+              mhi = multadd(mhi, 10, 0);
+              mlo = mhi;
             }
           else
             {
@@ -1698,7 +1848,7 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
     {
       for (i = 1; ; i++)
         {
-          *s++ = dig = quorem(b, S) + '0';
+          *st++ = dig = quorem(b, s) + '0';
           if (i >= ilim)
             {
               break;
@@ -1711,53 +1861,60 @@ char *__dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
   /* Round off last digit */
 
   b = lshift(b, 1);
-  j = cmp(b, S);
+  j = cmp(b, s);
+
   if (j > 0 || (j == 0 && (dig & 1)))
     {
-    roundoff:
-      while (*--s == '9')
-        if (s == s0)
-          {
-            k++;
-            *s++ = '1';
-            goto ret;
-          }
+roundoff:
+      while (*--st == '9')
+        {
+          if (st == st0)
+            {
+              k++;
+              *st++ = '1';
+              goto ret;
+            }
+        }
 
-      ++*s++;
+      ++*st++;
     }
   else
     {
-      while (*--s == '0');
-      s++;
+      while (*--st == '0')
+        {
+        }
+
+      st++;
     }
 
 ret:
-  Bfree(S);
+  bfree(s);
   if (mhi)
     {
       if (mlo && mlo != mhi)
         {
-          Bfree(mlo);
+          bfree(mlo);
         }
 
-      Bfree(mhi);
+      bfree(mhi);
     }
+
 ret1:
-  Bfree(b);
-  if (s == s0)
+  bfree(b);
+  if (st == st0)
     {
       /* Don't return empty string */
 
-      *s++ = '0';
-      k = 0;
+      *st++ = '0';
+      k     = 0;
     }
 
-  *s = 0;
+  *st = 0;
   *decpt = k + 1;
-  if (rve)
+  if (rve != NULL)
     {
-      *rve = s;
+      *rve = st;
     }
 
-  return s0;
+  return st0;
 }
diff --git a/libs/libc/stdio/lib_libdtoa.c b/libs/libc/stdio/lib_libdtoa.c
index d7015acae53..1bab3656ad0 100644
--- a/libs/libc/stdio/lib_libdtoa.c
+++ b/libs/libc/stdio/lib_libdtoa.c
@@ -58,26 +58,20 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-#define MAX_PREC 16
-
 #ifndef MIN
-#  define MIN(a,b) (a < b ? a : b)
+#  define MIN(a,b)          (a < b ? a : b)
 #endif
 
 #ifndef MAX
-#  define MAX(a,b) (a > b ? a : b)
+#  define MAX(a,b)          (a > b ? a : b)
 #endif
 
-/* Use (almost) the maximim precision with %g format if no precision is
- * specified.  We do not use the full precision beause the least significant
- * digits are probably garbage.
- *
- * REVISIT:  This should be smarter.  15 digits is the maximum size of the
- * number.  The maximum precision is really 15 minus the number of digits
- * in the integer part.
+/* Use the maximim precision with %g format if no precision is specified.
+ * NOTE:  This may result in numbers with precision that exceeds the
+ * precision of type double.
  */
 
-#define DOUBLE_PRECISON_MAX 13 /* vs 15 which is the maximum */
+#define DOUBLE_PRECISON_MAX 15
 
 /* Use a default precision of 6 for the %f format if no precision is
  * specified.
@@ -107,6 +101,24 @@ static void zeroes(FAR struct lib_outstream_s *obj, int nzeroes)
     }
 }
 
+/****************************************************************************
+ * Name: truncate_zeroes
+ *
+ * Description:
+ *   Adjust the string length to eliminate zeros in the fractional part of
+ *   the string.
+ *
+ ****************************************************************************/
+
+static inline int truncate_zeroes(FAR char *digits, int expt, int numlen)
+{
+  for (; numlen > expt && digits[numlen - 1] == '0'; numlen--)
+    {
+    }
+
+  return numlen;
+}
+
 /****************************************************************************
  * Name: lib_dtoa_string
  *
@@ -216,6 +228,28 @@ static void lib_dtoa(FAR struct lib_outstream_s *obj, int fmt, int prec,
   digits = __dtoa(value, 3, prec, &expt, &dsgn, &rve);
   numlen = rve - digits;
 
+  /* If we are going to truncate trailing zeros, then make sure we have not
+   * exceeded the precision of type double.
+   */
+
+  if (notrailing && numlen > DOUBLE_PRECISON_MAX)
+    {
+      /* Make sure there are fractional digits to truncate */
+
+      if (expt <= DOUBLE_PRECISON_MAX)
+        {
+          numlen = DOUBLE_PRECISON_MAX;
+        }
+      else
+        {
+          numlen = expt;
+        }
+
+      /* Shortening the string probably now exposes some trailing zeroes */
+
+      numlen =  truncate_zeroes(digits, expt, numlen);
+    }
+
   /* Avoid precision error from missing trailing zeroes */
 
   numlen = MAX(expt, numlen);