re PR preprocessor/23479 (Implement binary constants with a "0b" prefix)

2007-06-05  Joerg Wunsch  <j.gnu@uriah.heep.sax.de>

	PR preprocessor/23479
gcc/
	* doc/extend.texi: Document the 0b-prefixed binary integer
	constant extension.

libcpp/
	* expr.c (cpp_classify_number): Implement 0b-prefixed binary
	integer constants.
	(append_digit): Likewise.
	* include/cpplib.h: Add CPP_N_BINARY, to be used for 0b-prefixed
	binary integer constants.

testsuite/
	* testsuite/gcc.dg/binary-constants-1.c: Add test suites for
	the 0b-prefixed binary integer constants.
	* testsuite/gcc.dg/binary-constants-2.c: Ditto.
	* testsuite/gcc.dg/binary-constants-3.c: Ditto.
	* testsuite/gcc.dg/binary-constants-4.c: Ditto.

From-SVN: r125346

gcc/ChangeLog

+2007-06-05  Joerg Wunsch  <j.gnu@uriah.heep.sax.de>
+
+	PR preprocessor/23479
+	* doc/extend.texi: Document the 0b-prefixed binary integer
+	constant extension.
+	
 2007-06-05  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR tree-optimization/32215

gcc/doc/extend.texi

@@ -81,6 +81,7 @@ extensions, accepted by GCC in C89 mode and in C++.
 * 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
@@ -10860,6 +10861,28 @@ 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
 @cindex extensions, C++ language

gcc/testsuite/ChangeLog

+2007-06-05  Joerg Wunsch  <j.gnu@uriah.heep.sax.de>
+
+	PR preprocessor/23479
+	* testsuite/gcc.dg/binary-constants-1.c: Add test suites for
+	the 0b-prefixed binary integer constants.
+	* testsuite/gcc.dg/binary-constants-2.c: Ditto.
+	* testsuite/gcc.dg/binary-constants-3.c: Ditto.
+	* testsuite/gcc.dg/binary-constants-4.c: Ditto.
+	
 2007-06-05  Ian Lance Taylor  <iant@google.com>
 
 	* gcc.dg/Wstrict-overflow-19.c: New test.

gcc/testsuite/gcc.dg/binary-constants-2.c

+/* Test for binary integer constants: -pedantic warnings.  */
+
+/* Origin: Joerg Wunsch <j.gnu@uriah.heep.sax.de>.  */
+/* { dg-do compile } */
+/* { dg-options "-std=iso9899:1999 -pedantic" } */
+
+#define FOO 0b1101
+
+int
+foo (void)
+{
+#if FOO /* { dg-warning "binary constants are a GCC extension" } */
+  return 23;
+#endif
+  return 0b1101; /* { dg-warning "binary constants are a GCC extension" } */
+}

gcc/testsuite/gcc.dg/binary-constants-3.c

+/* Test for binary integer constants: -pedantic-errors.  */
+
+/* Origin: Joerg Wunsch <j.gnu@uriah.heep.sax.de>.  */
+/* { dg-do compile } */
+/* { dg-options "-std=iso9899:1999 -pedantic-errors" } */
+
+#define FOO 0b1101
+
+int
+foo (void)
+{
+#if FOO /* { dg-error "binary constants are a GCC extension" } */
+  return 23;
+#endif
+  return 0b1101; /* { dg-error "binary constants are a GCC extension" } */
+}

gcc/testsuite/gcc.dg/binary-constants-4.c

+/* Test for binary integer constants: random errors.  */
+
+/* Origin: Joerg Wunsch <j.gnu@uriah.heep.sax.de>.  */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99" } */
+
+void
+foo(void)
+{
+  double d;
+  int i;
+
+  d = 0b1101;
+  d = 0b1101p1; /* { dg-error "invalid suffix \"p1\" on integer constant" } */
+  d = 0x1101p1;
+  i = 0b3011;   /* { dg-error "invalid suffix \"b3011\" on integer constant" } */
+  i = 0b113;    /* { dg-error "invalid digit \"3\" in binary constant" } */
+}

libcpp/ChangeLog

+2007-06-05  Joerg Wunsch  <j.gnu@uriah.heep.sax.de>
+
+	PR preprocessor/23479
+	* expr.c (cpp_classify_number): Implement 0b-prefixed binary
+	integer constants.
+	(append_digit): Likewise.
+	* include/cpplib.h: Add CPP_N_BINARY, to be used for 0b-prefixed
+	binary integer constants.
+
 2007-05-31  Dave Korn  <dave.korn@artimi.com>
 
 	PR preprocessor/14331

libcpp/expr.c

@@ -185,6 +185,11 @@ cpp_classify_number (cpp_reader *pfile, const cpp_token *token)
 	  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.  */
@@ -223,10 +228,22 @@ cpp_classify_number (cpp_reader *pfile, const cpp_token *token)
     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");
@@ -315,11 +332,16 @@ cpp_classify_number (cpp_reader *pfile, const cpp_token *token)
   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;
 
@@ -370,6 +392,11 @@ cpp_interpret_integer (cpp_reader *pfile, const cpp_token *token,
 	  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.  */
@@ -425,12 +452,25 @@ static cpp_num
 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;

libcpp/include/cpplib.h

@@ -748,6 +748,7 @@ struct cpp_num
 #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