--- ./gcc/doc/extend.texi.orig	Sat Aug  6 15:26:27 2005
+++ ./gcc/doc/extend.texi	Mon Aug 22 00:14:05 2005
@@ -79,6 +79,7 @@
 * Pragmas::             Pragmas accepted by GCC.
 * Unnamed Fields::      Unnamed struct/union fields within structs/unions.
 * Thread-Local::        Per-thread variables.
+* Binary constants::    Binary constants using the @samp{0b} prefix.
 @end menu
 
 @node Statement Exprs
@@ -9742,6 +9743,28 @@
 Non-@code{static} members shall not be @code{__thread}.
 @end quotation
 @end itemize
+
+@node Binary constants
+@section Binary constants using the @samp{0b} prefix
+@cindex Binary constants using the @samp{0b} prefix
+
+Integer constants can be written as binary constants, consisting of a
+sequence of @samp{0} and @samp{1} digits, prefixed by @samp{0b} or
+@samp{0B}.  This is particularly useful in environments that operate a
+lot on the bit-level (like microcontrollers).
+
+The following statements are identical:
+
+@smallexample
+i =       42;
+i =     0x2a;
+i =      052;
+i = 0b101010;
+@end smallexample
+
+The type of these constants follows the same rules as for octal or
+hexadecimal integer constants, so suffixes like @samp{L} or @samp{UL}
+can be applied.
 
 @node C++ Extensions
 @chapter Extensions to the C++ Language
--- ./libcpp/include/cpplib.h.orig	Wed Jun 29 04:34:39 2005
+++ ./libcpp/include/cpplib.h	Mon Aug 22 00:14:05 2005
@@ -729,6 +729,7 @@
 #define CPP_N_DECIMAL	0x0100
 #define CPP_N_HEX	0x0200
 #define CPP_N_OCTAL	0x0400
+#define CPP_N_BINARY	0x0800
 
 #define CPP_N_UNSIGNED	0x1000	/* Properties.  */
 #define CPP_N_IMAGINARY	0x2000
--- ./libcpp/expr.c.orig	Wed Jun 29 04:34:36 2005
+++ ./libcpp/expr.c	Mon Aug 22 12:02:28 2005
@@ -171,6 +171,11 @@
 	  radix = 16;
 	  str++;
 	}
+      else if ((*str == 'b' || *str == 'B') && (str[1] == '0' || str[1] == '1'))
+	{
+	  radix = 2;
+	  str++;
+	}
     }
 
   /* Now scan for a well-formed integer or float.  */
@@ -209,10 +214,22 @@
     radix = 10;
 
   if (max_digit >= radix)
-    SYNTAX_ERROR2 ("invalid digit \"%c\" in octal constant", '0' + max_digit);
+    {
+      if (radix == 2)
+	SYNTAX_ERROR2 ("invalid digit \"%c\" in binary constant", '0' + max_digit);
+      else
+	SYNTAX_ERROR2 ("invalid digit \"%c\" in octal constant", '0' + max_digit);
+    }
 
   if (float_flag != NOT_FLOAT)
     {
+      if (radix == 2)
+	{
+	  cpp_error (pfile, CPP_DL_ERROR,
+		     "invalid prefix \"0b\" for floating constant");
+	  return CPP_N_INVALID;
+	}
+
       if (radix == 16 && CPP_PEDANTIC (pfile) && !CPP_OPTION (pfile, c99))
 	cpp_error (pfile, CPP_DL_PEDWARN,
 		   "use of C99 hexadecimal floating constant");
@@ -288,11 +305,16 @@
   if ((result & CPP_N_IMAGINARY) && CPP_PEDANTIC (pfile))
     cpp_error (pfile, CPP_DL_PEDWARN,
 	       "imaginary constants are a GCC extension");
+  if (radix == 2 && CPP_PEDANTIC (pfile))
+    cpp_error (pfile, CPP_DL_PEDWARN,
+	       "binary constants are a GCC extension");
 
   if (radix == 10)
     result |= CPP_N_DECIMAL;
   else if (radix == 16)
     result |= CPP_N_HEX;
+  else if (radix == 2)
+    result |= CPP_N_BINARY;
   else
     result |= CPP_N_OCTAL;
 
@@ -343,6 +365,11 @@
 	  base = 16;
 	  p += 2;
 	}
+      else if ((type & CPP_N_RADIX) == CPP_N_BINARY)
+	{
+	  base = 2;
+	  p += 2;
+	}
 
       /* We can add a digit to numbers strictly less than this without
 	 needing the precision and slowness of double integers.  */
@@ -398,12 +425,25 @@
 append_digit (cpp_num num, int digit, int base, size_t precision)
 {
   cpp_num result;
-  unsigned int shift = 3 + (base == 16);
+  unsigned int shift;
   bool overflow;
   cpp_num_part add_high, add_low;
 
-  /* Multiply by 8 or 16.  Catching this overflow here means we don't
+  /* Multiply by 2, 8 or 16.  Catching this overflow here means we don't
      need to worry about add_high overflowing.  */
+  switch (base)
+    {
+    case 2:
+      shift = 1;
+      break;
+
+    case 16:
+      shift = 4;
+      break;
+
+    default:
+      shift = 3;
+    }
   overflow = !!(num.high >> (PART_PRECISION - shift));
   result.high = num.high << shift;
   result.low = num.low << shift;