Use struct for Dec128

Author: jmkuhn

src/DecFP.jl

@@ -109,11 +109,18 @@ Base.Rounding.rounding(::Type{T}) where {T<:DecimalFloatingPoint} =
 Base.Rounding.setrounding(::Type{T}, r::RoundingMode) where {T<:DecimalFloatingPoint} =
     Base.Rounding.setrounding_raw(T, convert(DecFPRoundingMode, r))
 
+primitive type Dec32 <: DecimalFloatingPoint 32 end
+primitive type Dec64 <: DecimalFloatingPoint 64 end
+Dec32(x::Number) = convert(Dec32, x)
+Dec64(x::Number) = convert(Dec64, x)
+struct Dec128 <: DecimalFloatingPoint
+    x::UInt128
+    Dec128(x::Number) = convert(Dec128, x)
+    Base.reinterpret(::Type{Dec128}, x::UInt128) = new(x)
+end
 for w in (32,64,128)
     BID = Symbol(string("Dec",w))
     Ti = Symbol(string("UInt",w))
-    @eval primitive type $BID <: DecimalFloatingPoint $w end
-    $BID(x::Number) = convert($BID, x)
 
     @eval function $BID(x::Real, mode::RoundingMode)
         setrounding($BID, mode) do
@@ -613,11 +620,15 @@ for w in (32,64,128)
         end
     end
 
-    @eval Base.bswap(x::$BID) = reinterpret($BID, bswap(reinterpret($Ti, x)))
     @eval Base.convert(::Type{Float16}, x::$BID) = convert(Float16, convert(Float32, x))
     @eval Base.Float16(x::$BID) = convert(Float16, x)
 end # widths w
 
+Base.reinterpret(::Type{UInt128}, x::Dec128) = x.x
+Base.bswap(x::Dec32) = reinterpret(Dec32, bswap(reinterpret(UInt32, x)))
+Base.bswap(x::Dec64) = reinterpret(Dec64, bswap(reinterpret(UInt64, x)))
+Base.bswap(x::Dec128) = reinterpret(Dec128, bswap(x.x))
+
 Base.round(x::DecimalFloatingPoint, ::RoundingMode{:FromZero}) = signbit(x) ? floor(x) : ceil(x)
 
 for (f) in (:trunc, :floor, :ceil)