Add config to enable floating point support

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2542 42af7a65-404d-4744-a932-0658087f49c3

Documentation/NuttxPortingGuide.html

@@ -2397,6 +2397,10 @@ extern void up_ledoff(int led);
     <code>CONFIG_NOPRINTF_FIELDWIDTH</code>: sprintf-related logic is a
     little smaller if we do not support fieldwidthes
   </li>
+  <li>
+    <code>CONFIG_LIBC_FLOATINGPOINT</code>: By default, floating point
+    support in printf, sscanf, etc. is disabled.
+  </li>
 </ul>
 
 <h2>Allow for architecture optimized implementations</h2>

configs/README.txt

@@ -282,6 +282,8 @@ defconfig -- This is a configuration file similar to the Linux
 
 		CONFIG_NOPRINTF_FIELDWIDTH - sprintf-related logic is a
 		   little smaller if we do not support fieldwidthes
+		CONFIG_LIBC_FLOATINGPOINT - By default, floating point
+		  support in printf, sscanf, etc. is disabled.
 
 	Allow for architecture optimized implementations
 

lib/lib_libvsprintf.c

@@ -1465,12 +1465,14 @@ int lib_vsprintf(FAR struct lib_outstream_s *obj, const char *src, va_list ap)
 
       /* Handle floating point conversions */
 
+#ifdef CONFIG_LIBC_FLOATINGPOINT
       else if (strchr("eEfgG", *src))
         {
 #ifdef CONFIG_CPP_HAVE_WARNING
 #  warning "No floating point support"
 #endif
         }
+#endif
     }
 
   return obj->nput;

lib/lib_sscanf.c

@@ -260,10 +260,9 @@ int vsscanf(char *buf, const char *s, va_list ap)
 
           else if (*s == 'f')
             {
-#if 1
-#  ifdef CONFIG_CPP_HAVE_WARNING
-#    warning "No floating point conversions"
-#  endif
+#ifndef CONFIG_LIBC_FLOATINGPOINT
+              /* No floating point conversions */
+
               void *pv = va_arg(ap, void*);
 
               lvdbg("vsscanf: Return 0.0 to %p\n", pv);
@@ -331,7 +330,9 @@ int vsscanf(char *buf, const char *s, va_list ap)
             }
 
           if (!noassign)
-            count++;
+            {
+              count++;
+            }
           width = noassign = lflag = 0;
           s++;
         }