Merged the decimal-branch (revisions 54886 to 58140). Decimal is now
fully updated to the latests Decimal Specification (v1.66) and the
latests test cases (v2.56).

Thanks to Mark Dickinson for all his help during this process.
diff --git a/Lib/test/decimaltestdata/ddMinus.decTest b/Lib/test/decimaltestdata/ddMinus.decTest
new file mode 100644
index 0000000..9fe196b
--- /dev/null
+++ b/Lib/test/decimaltestdata/ddMinus.decTest
@@ -0,0 +1,88 @@
+------------------------------------------------------------------------

+-- ddMinus.decTest -- decDouble 0-x                                   --

+-- Copyright (c) IBM Corporation, 1981, 2007.  All rights reserved.   --

+------------------------------------------------------------------------

+-- Please see the document "General Decimal Arithmetic Testcases"     --

+-- at http://www2.hursley.ibm.com/decimal for the description of      --

+-- these testcases.                                                   --

+--                                                                    --

+-- These testcases are experimental ('beta' versions), and they       --

+-- may contain errors.  They are offered on an as-is basis.  In       --

+-- particular, achieving the same results as the tests here is not    --

+-- a guarantee that an implementation complies with any Standard      --

+-- or specification.  The tests are not exhaustive.                   --

+--                                                                    --

+-- Please send comments, suggestions, and corrections to the author:  --

+--   Mike Cowlishaw, IBM Fellow                                       --

+--   IBM UK, PO Box 31, Birmingham Road, Warwick CV34 5JL, UK         --

+--   mfc@uk.ibm.com                                                   --

+------------------------------------------------------------------------

+version: 2.56

+

+-- All operands and results are decDoubles.

+precision:   16

+maxExponent: 384

+minExponent: -383

+extended:    1

+clamp:       1

+rounding:    half_even

+

+-- Sanity check

+ddmns001 minus       +7.50  -> -7.50

+

+-- Infinities

+ddmns011 minus  Infinity    -> -Infinity

+ddmns012 minus  -Infinity   -> Infinity

+

+-- NaNs, 0 payload

+ddmns021 minus         NaN  -> NaN

+ddmns022 minus        -NaN  -> -NaN

+ddmns023 minus        sNaN  -> NaN  Invalid_operation

+ddmns024 minus       -sNaN  -> -NaN Invalid_operation

+

+-- NaNs, non-0 payload

+ddmns031 minus       NaN13  -> NaN13

+ddmns032 minus      -NaN13  -> -NaN13

+ddmns033 minus      sNaN13  -> NaN13   Invalid_operation

+ddmns034 minus     -sNaN13  -> -NaN13  Invalid_operation

+ddmns035 minus       NaN70  -> NaN70

+ddmns036 minus      -NaN70  -> -NaN70

+ddmns037 minus      sNaN101 -> NaN101  Invalid_operation

+ddmns038 minus     -sNaN101 -> -NaN101 Invalid_operation

+

+-- finites

+ddmns101 minus          7   -> -7

+ddmns102 minus         -7   -> 7

+ddmns103 minus         75   -> -75

+ddmns104 minus        -75   -> 75

+ddmns105 minus       7.50   -> -7.50

+ddmns106 minus      -7.50   -> 7.50

+ddmns107 minus       7.500  -> -7.500

+ddmns108 minus      -7.500  -> 7.500

+

+-- zeros

+ddmns111 minus          0   -> 0

+ddmns112 minus         -0   -> 0

+ddmns113 minus       0E+4   -> 0E+4

+ddmns114 minus      -0E+4   -> 0E+4

+ddmns115 minus     0.0000   -> 0.0000

+ddmns116 minus    -0.0000   -> 0.0000

+ddmns117 minus      0E-141  -> 0E-141

+ddmns118 minus     -0E-141  -> 0E-141

+

+-- full coefficients, alternating bits

+ddmns121 minus  2682682682682682         -> -2682682682682682

+ddmns122 minus  -2682682682682682        -> 2682682682682682

+ddmns123 minus  1341341341341341         -> -1341341341341341

+ddmns124 minus  -1341341341341341        -> 1341341341341341

+

+-- Nmax, Nmin, Ntiny

+ddmns131 minus  9.999999999999999E+384   -> -9.999999999999999E+384

+ddmns132 minus  1E-383                   -> -1E-383

+ddmns133 minus  1.000000000000000E-383   -> -1.000000000000000E-383

+ddmns134 minus  1E-398                   -> -1E-398 Subnormal

+

+ddmns135 minus  -1E-398                  -> 1E-398 Subnormal

+ddmns136 minus  -1.000000000000000E-383  -> 1.000000000000000E-383

+ddmns137 minus  -1E-383                  -> 1E-383

+ddmns138 minus  -9.999999999999999E+384  -> 9.999999999999999E+384