Inf128, typemin/max (#30)

* Inf128, typemin/max
* revise test sequence to isolate fma issue

Author: RalphAS

src/Quadmath.jl

@@ -1,7 +1,7 @@
 module Quadmath
 using Requires
 
-export Float128, ComplexF128
+export Float128, ComplexF128, Inf128
 
 import Base: (*), +, -, /,  <, <=, ==, ^, convert,
           reinterpret, sign_mask, exponent_mask, exponent_one, exponent_half,
@@ -13,7 +13,7 @@ import Base: (*), +, -, /,  <, <=, ==, ^, convert,
           tan, tanh,
           ceil, floor, trunc, round, fma,
           copysign, flipsign, max, min, hypot, abs,
-          ldexp, frexp, modf, nextfloat, eps,
+          ldexp, frexp, modf, nextfloat, typemax, typemin, eps,
           isinf, isnan, isfinite, isinteger,
           floatmin, floatmax, precision, signbit, maxintfloat,
           Int32, Int64, Float64, BigFloat, BigInt
@@ -368,6 +368,14 @@ floatmin(::Type{Float128}) = reinterpret(Float128, 0x0001_0000_0000_0000_0000_00
 floatmax(::Type{Float128}) = reinterpret(Float128, 0x7ffe_ffff_ffff_ffff_ffff_ffff_ffff_ffff)
 
 maxintfloat(::Type{Float128}) = Float128(0x0002_0000_0000_0000_0000_0000_0000_0000)
+"""
+    Inf128
+
+Positive infinity of type [`Float128`](@ref).
+"""
+const Inf128 = reinterpret(Float128, 0x7fff_0000_0000_0000_0000_0000_0000_0000)
+typemax(::Type{Float128}) = Inf128
+typemin(::Type{Float128}) = -Inf128
 
 ldexp(x::Float128, n::Cint) =
     Float128(@ccall(libquadmath.ldexpq(x::Cfloat128, n::Cint)::Cfloat128))

test/runtests.jl

@@ -92,6 +92,25 @@ end
     @test x+y == ipart+fpart
 end
 
+isnan128(x) = isa(x, Float128) && isnan(x)
+isinf128(x) = isa(x, Float128) && isinf(x)
+
+@testset "nonfinite" begin
+    Zero = Float128(0)
+    One = Float128(1)
+    huge = floatmax(Float128)
+    myinf = huge + huge
+    myminf = -myinf
+    @test isinf128(myinf)
+    @test isnan128(Zero / Zero)
+    @test isinf128(One / Zero)
+    @test isnan128(myinf - myinf)
+    @test isnan128(myinf + myminf)
+    @test Inf128 === myinf
+    @test typemax(Float128) === myinf
+    @test typemin(Float128) === myminf
+end
+
 @testset "transcendental etc. calls" begin
     # at least enough to cover all the wrapping code
     x = sqrt(Float128(2.0))
@@ -101,7 +120,14 @@ end
     @test abs(x) == x
     @test hypot(Float128(3),Float128(4)) == Float128(5)
     @test atan(x,x) ≈ Float128(pi) / 4
+    h = floatmax(Float128)
+    @test isinf(h+h)
     @test fma(x,x,Float128(-1.0)) ≈ Float128(1)
+    if Sys.iswindows()
+        @test_broken isinf(h+h)
+    else
+        @test isinf(h+h)
+    end
 end
 
 @testset "misc. math" begin