Fix trunc of FD at the input limits

Author: omus

src/FixedPointDecimals.jl

@@ -161,7 +161,7 @@ function /{T, f}(x::FD{T, f}, y::Integer)
 end
 
 # integerification
-trunc{T, f}(x::FD{T, f}) = FD{T, f}(div(x.i, T(10)^f))
+trunc{T, f}(x::FD{T, f}) = FD{T, f}(div(x.i, coefficient(FD{T, f})))
 floor{T, f}(x::FD{T, f}) = FD{T, f}(fld(x.i, T(10)^f))
 # TODO: round with number of digits; should be easy
 function round{T, f}(x::FD{T, f}, ::RoundingMode{:Nearest}=RoundNearest)

test/runtests.jl

@@ -481,6 +481,10 @@ end
                 # we can have the expected result be a little flexible.
                 @test value(trunc(FD{$T,$f}, max_int / powt)) in [max_int, max_int - 1]
                 @test value(trunc(FD{$T,$f}, min_int / powt)) in [min_int, min_int + 1]
+
+                # Note: all values `x` in FD{T,f} are -1 < x < 1
+                @test trunc(reinterpret(FD{$T,$f}, typemax($T))) == zero(FD{$T,$f})
+                @test trunc(reinterpret(FD{$T,$f}, typemin($T))) == zero(FD{$T,$f})
             end
         end
     end