Test cases from Cowlishaw, v2.57. All are pased cleanly.
diff --git a/Lib/test/decimaltestdata/add.decTest b/Lib/test/decimaltestdata/add.decTest
index 3460aa4..8db222a 100644
--- a/Lib/test/decimaltestdata/add.decTest
+++ b/Lib/test/decimaltestdata/add.decTest
@@ -17,7 +17,7 @@
-- IBM UK, PO Box 31, Birmingham Road, Warwick CV34 5JL, UK --
-- mfc@uk.ibm.com --
------------------------------------------------------------------------
-version: 2.56
+version: 2.57
precision: 9
rounding: half_up
@@ -1122,6 +1122,15 @@
addx1117 add -1e-4 +1e-383 -> -0.00009999999999999999 Rounded Inexact
addx1118 add -1e-5 +1e-383 -> -0.000009999999999999999 Rounded Inexact
addx1119 add -1e-6 +1e-383 -> -9.999999999999999E-7 Rounded Inexact
+addx1120 add +1e-383 -1e+2 -> -99.99999999999999 Rounded Inexact
+addx1121 add +1e-383 -1e+1 -> -9.999999999999999 Rounded Inexact
+addx1123 add +1e-383 -1 -> -0.9999999999999999 Rounded Inexact
+addx1124 add +1e-383 -1e-1 -> -0.09999999999999999 Rounded Inexact
+addx1125 add +1e-383 -1e-2 -> -0.009999999999999999 Rounded Inexact
+addx1126 add +1e-383 -1e-3 -> -0.0009999999999999999 Rounded Inexact
+addx1127 add +1e-383 -1e-4 -> -0.00009999999999999999 Rounded Inexact
+addx1128 add +1e-383 -1e-5 -> -0.000009999999999999999 Rounded Inexact
+addx1129 add +1e-383 -1e-6 -> -9.999999999999999E-7 Rounded Inexact
rounding: down
precision: 7
@@ -1658,17 +1667,19 @@
addx6057 add '1E+2' '1E+4' -> '1.01E+4'
-- from above
-addx6061 add 1 '0.1' -> '1.1'
-addx6062 add 1 '0.01' -> '1.01'
-addx6063 add 1 '0.001' -> '1.001'
-addx6064 add 1 '0.0001' -> '1.0001'
-addx6065 add 1 '0.00001' -> '1.00001'
-addx6066 add 1 '0.000001' -> '1.000001'
-addx6067 add 1 '0.0000001' -> '1.0000001'
-addx6068 add 1 '0.00000001' -> '1.00000001'
+addx6060 add 1 '0.1' -> '1.1'
+addx6061 add 1 '0.01' -> '1.01'
+addx6062 add 1 '0.001' -> '1.001'
+addx6063 add 1 '0.0001' -> '1.0001'
+addx6064 add 1 '0.00001' -> '1.00001'
+addx6065 add 1 '0.000001' -> '1.000001'
+addx6066 add 1 '0.0000001' -> '1.0000001'
+addx6067 add 1 '0.00000001' -> '1.00000001'
-- cancellation to integer
-addx6069 add 99999999999999123456789 -99999999999999E+9 -> 123456789
+addx6068 add 99999999999999123456789 -99999999999999E+9 -> 123456789
+-- similar from FMA fun
+addx6069 add "-1234567890123455.234567890123454" "1234567890123456" -> 0.765432109876546
-- some funny zeros [in case of bad signum]
addx6070 add 1 0 -> 1