Add bignum fall-back when the fast dtoa doesn't succeed. This removes Gay's d...

src/bignum-dtoa.h

Index: src/bignum-dtoa.h
===================================================================
--- src/bignum-dtoa.h	(revision 0)
+++ src/bignum-dtoa.h	(revision 0)
@@ -0,0 +1,81 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_BIGNUM_DTOA_H_
+#define V8_BIGNUM_DTOA_H_
+
+namespace v8 {
+namespace internal {
+
+enum BignumDtoaMode {
+  // 0.9999999999999999 becomes 0.1

[William Hesse, 2010/11/15 15:48:30]

Better description, not just an example.

Or say "see below, at declaration of BignumDtoa."

[Florian Loitsch, 2010/11/16 14:32:06]

Done.

+  BIGNUM_DTOA_SHORTEST,
+  // Fixed number of digits after the comma.

[William Hesse, 2010/11/15 15:48:30]

Return a fixed number of digits after the decimal point (or radix point).

[Florian Loitsch, 2010/11/16 14:32:06]

Done.

+  // For instance fixed(0.1, 4) becomes 0.1000
+  // If the input number is big, the output will be big.
+  BIGNUM_DTOA_FIXED,
+  // Fixed number of digits (independent of the comma).

[William Hesse, 2010/11/15 15:48:30]

Return a fixed number of digits, no matter what the exponent is.

[Florian Loitsch, 2010/11/16 14:32:06]

Done.

+  BIGNUM_DTOA_PRECISION
+};
+
+// Converts the given double 'v' to ascii.
+// The result should be interpreted as buffer * 10^(point-length).
+// The buffer will be null-terminated.
+//
+// The input v must be > 0 and different from NaN, and Infinity.
+//
+// The output depends on the given mode:
+//  - SHORTEST: produce the least amount of digits for which the internal
+//   identity requirement is still satisfied. If the digits are printed
+//   (together with the correct exponent) then reading this number will give
+//   'v' again. The buffer will choose the representation that is closest to
+//   'v'. If there are two at the same distance, than the number is round up.
+//   In this mode the 'requested_digits' parameter is ignored.
+//  - FIXED: produces digits necessary to print a given number with
+//   'requested_digits' digits after the comma. The produced digits might be too

[William Hesse, 2010/11/15 15:48:30]

decimal point, radix point.

[Florian Loitsch, 2010/11/16 14:32:06]

Done.

+//   short in which case the caller has to fill the gaps with '0's.
+//   Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2.
+//   Halfway cases are rounded up. The call toFixed(0.15, 2) thus returns
+//     buffer="2", point=0.
+//   Note: the length of the returned buffer has no meaning wrt the significance
+//   of its digits. That is, just because it contains '0's does not mean that
+//   any other digit would not satisfy the internal identity requirement.
+//  - PRECISION: produces 'requested_digits' where the first digit is not '0'.
+//   Even though the length of produced digits usually equals
+//   'requested_digits', the function is allowed to return less digits, in which

[William Hesse, 2010/11/15 15:48:30]

fewer

[Florian Loitsch, 2010/11/16 14:32:06]

Done.

+//   case the caller has to fill the missing digits with '0's.
+//   Halfway cases are again rounded up.
+// The given memory-management functions are only needed for internal bignum

[William Hesse, 2010/11/15 15:48:30]

No memory management functions are passed in anymore.

[Florian Loitsch, 2010/11/16 14:32:06]

Done.

+// computations. If they are NULL then the system ones will be used.
+// 'DoubleToAscii' expects the given buffer to be big enough to hold all digits
+// and a terminating null-character.
+void BignumDtoa(double v, BignumDtoaMode mode, int requested_digits,
+                Vector<char> buffer, int* length, int* point);
+
+} }  // namespace v8::internal
+
+#endif  // V8_BIGNUM_DTOA_H_