Add trunc(x), floor(x), ceil(x) (#61)

* Add trunc(x), floor(x), ceil(x)

* Use signbit

Author: jmkuhn

src/DecFP.jl

@@ -303,10 +303,12 @@ for w in (32,64,128)
         @eval Base.$f(x::$BID) = @xchk(ccall(($(bidsym(w,f)), libbid), $BID, ($BID,), x), DomainError, x, mask=INVALID)
     end
 
-    for (f,c) in ((:gamma,"tgamma"), (:-,"negate"), (:round,"nearbyint"))
+    for (f,c) in ((:gamma,"tgamma"), (:-,"negate"), (:trunc,"round_integral_zero"), (:floor,"round_integral_negative"), (:ceil,"round_integral_positive"), (:round,"nearbyint"))
         @eval Base.$f(x::$BID) = @xchk(ccall(($(bidsym(w,c)), libbid), $BID, ($BID,), x), DomainError, x, mask=INVALID)
     end
 
+    @eval Base.round(x::$BID, ::RoundingMode{:Nearest}) = @xchk(ccall(($(bidsym(w,"round_integral_nearest_even")), libbid), $BID, ($BID,), x), DomainError, x, mask=INVALID)
+
     for (f,c) in ((:(==),"quiet_equal"), (:>,"quiet_greater"), (:<,"quiet_less"), (:(>=), "quiet_greater_equal"), (:(<=), "quiet_less_equal"))
         @eval Base.$f(x::$BID, y::$BID) = nox(ccall(($(bidsym(w,c)), libbid), Cint, ($BID,$BID), x, y) != 0)
     end
@@ -374,6 +376,8 @@ for w in (32,64,128)
     @eval Base.reinterpret(::Type{$Ti}, x::$BID) = x.x
 end # widths w
 
+Base.round(x::DecimalFloatingPoint, ::RoundingMode{:FromZero}) = signbit(x) ? floor(x) : ceil(x)
+
 Base.trunc(::Type{Integer}, x::DecimalFloatingPoint) = trunc(Int, x)
 Base.floor(::Type{Integer}, x::DecimalFloatingPoint) = floor(Int, x)
 Base.ceil(::Type{Integer}, x::DecimalFloatingPoint) = ceil(Int, x)

test/runtests.jl

@@ -153,6 +153,13 @@ for T in (Dec32, Dec64, Dec128)
     for Tf in (Float64, Float32, Float16)
         @test xd == Tf(x) == T(Tf(x)) == Tf(xd)
     end
+
+    @test trunc(T(2.7)) === floor(T(2.7)) === round(T(2.7), RoundDown) === round(T(2.7), RoundToZero) === T(2)
+    @test ceil(T(2.3)) === round(T(2.3), RoundUp) === round(T(2.3), RoundFromZero) === T(3)
+    @test round(T(1.5)) === round(T(2.5)) === round(T(1.5), RoundNearest) === round(T(2.5), RoundNearest) === T(2)
+    @test round(T(2.5), RoundNearestTiesAway) === round(T(3.3), RoundNearestTiesAway) === T(3)
+    @test round(T(2.5), RoundNearestTiesUp) === round(T(3.3), RoundNearestTiesUp) === T(3)
+
     for Ti in (Integer,Int8,UInt8,Int16,UInt16,Int32,UInt32,Int64,UInt64)
         if Ti != Integer
             @test parse(T, "17") == T(Ti(17)) == Ti(17) == Ti(T(17))