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--- ./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;
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