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CPM OPERATING SYSTEMS/CPM 68K/1.0X SOURCES/v101/vms/ftoa.c

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+ftoa (x, str, prec, format)
+float x;
+char *str;
+{
+/* converts a floating point number to an ascii string */
+/* x is stored into str, which should be at least 30 chars long */
+int ie, i, k, ndig, fstyle;
+double y;
+ndig = ( prec<=0) ? 7 : (prec > 22 ? 23 : prec+1);
+if  (format == 'f' || format == 'F')
+ fstyle = 1;
+else
+ fstyle = 0;
+/* print in e format unless last arg is 'f' */
+ie = 0;
+/* if x negative, write minus and reverse */
+if ( x < 0)
+  {
+  *str++ = '-';
+  x = -x;
+  }
+
+/* put x in range 1 <= x < 10 */
+if (x > 0.0) while (x < 1.0)
+  {
+  x =* 10.0;
+  ie--;
+  }
+while (x >= 10.0)
+  {
+  x = x/10.0;
+  ie++;
+  }
+
+/* in f format, number of digits is related to size */
+if (fstyle) ndig =+ ie;
+
+/* round. x is between 1 and 10 and ndig will be printed to
+   right of decimal point so rounding is ... */
+for (y = i = 1; i < ndig; i++)
+  y = y/10.;
+x =+ y/2.;
+if (x >= 10.0) {x = 1.0; ie++;} /* repair rounding disasters */
+/* now loop.  put out a digit (obtain by multiplying by
+  10, truncating, subtracting) until enough digits out */
+/* if fstyle, and leading zeros, they go out special */
+if (fstyle && ie<0)
+  {
+  *str++ = '0'; *str++ = '.';
+  if (ndig < 0) ie = ie-ndig; /* limit zeros if underflow */
+  for (i = -1; i > ie; i--)
+    *str++ = '0';
+  }
+for (i=0; i < ndig; i++)
+  {
+  k = x;
+  *str++ = k + '0';
+  if (i == (fstyle ? ie : 0)) /* where is decimal point */
+    *str++ = '.';
+  x =- (y=k);
+  x =* 10.0;
+  }
+
+/* now, in estyle,  put out exponent if not zero */
+if (!fstyle && ie != 0)
+  {
+  *str++ = 'E';
+  if (ie < 0)
+    {
+    ie = -ie;
+    *str++ = '-';
+    }
+  for (k=100; k > ie; k =/10);
+  for (; k > 0; k =/10)
+       {
+       *str++ = ie/k + '0';
+       ie = ie%k;
+       }
+  }
+*str = '\0';
+return;
+}