Add checked_mul for type suffix (#210)

This prevents MethodError due to lexical replacement of implicit `*` by macros.
The constructors still check the input range by default.

Author: kimikage

src/FixedPointNumbers.jl

@@ -12,7 +12,7 @@ import Base: ==, <, <=, -, +, *, /, ~, isapprox,
 import Statistics   # for _mean_promote
 import Random: Random, AbstractRNG, SamplerType, rand!
 
-import Base.Checked: checked_neg, checked_add, checked_sub, checked_div
+import Base.Checked: checked_neg, checked_add, checked_sub, checked_mul, checked_div
 
 using Base: @pure
 
@@ -36,8 +36,8 @@ export
     # Q and N typealiases are exported in separate source files
 # Functions
     scaledual,
-    wrapping_neg, wrapping_add, wrapping_sub,
-    saturating_neg, saturating_add, saturating_sub
+    wrapping_neg, wrapping_add, wrapping_sub, wrapping_mul,
+    saturating_neg, saturating_add, saturating_sub, saturating_mul
 
 include("utilities.jl")
 
@@ -56,6 +56,9 @@ nbitsint(::Type{X}) where {X <: FixedPoint} = bitwidth(X) - nbitsfrac(X) - signb
 
 # construction using the (approximate) intended value, i.e., N0f8
 *(x::Real, ::Type{X}) where {X <: FixedPoint} = _convert(X, x)
+wrapping_mul(x::Real, ::Type{X}) where {X <: FixedPoint} = x % X
+saturating_mul(x::Real, ::Type{X}) where {X <: FixedPoint} = clamp(x, X)
+checked_mul(x::Real, ::Type{X}) where {X <: FixedPoint} = _convert(X, x)
 
 # constructor-style conversions
 (::Type{X})(x::X) where {X <: FixedPoint}      = x

test/fixed.jl

@@ -64,6 +64,23 @@ end
     @test_throws DomainError zero(Fixed{Int16,17})
 end
 
+@testset "construction using type suffix" begin
+    @test 0.635Q0f7  ===  Q0f7(0.635)
+    @test 0.635Q5f10 === Q5f10(0.635)
+    @test 0.635Q3f12 === Q3f12(0.635)
+    @test 0.635Q1f14 === Q1f14(0.635)
+    @test 0.635Q0f15 === Q0f15(0.635)
+
+    @test_throws ArgumentError 1.1Q0f7
+
+    @test wrapping_mul(0.635, Q0f7) === Q0f7(0.635)
+    @test wrapping_mul(1.635, Q0f7) === Q0f7(-0.365)
+    @test saturating_mul(0.635, Q0f7) === Q0f7(0.635)
+    @test saturating_mul(1.635, Q0f7) === Q0f7(0.992)
+    @test checked_mul(0.635, Q0f7) === Q0f7(0.635)
+    @test_throws ArgumentError checked_mul(1.635, Q0f7)
+end
+
 @testset "reinterpret/bitstring" begin
     @test reinterpret(Q0f7, signed(0xa2)) === -0.734375Q0f7
     @test reinterpret(Q5f10, signed(0x00a2)) === 0.158203125Q5f10

test/normed.jl

@@ -12,6 +12,23 @@ end
     @test_throws DomainError zero(Normed{UInt16,17})
 end
 
+@testset "construction using type suffix" begin
+    @test 0.635N0f8  ===  N0f8(0.635)
+    @test 0.635N6f10 === N6f10(0.635)
+    @test 0.635N4f12 === N4f12(0.635)
+    @test 0.635N2f14 === N2f14(0.635)
+    @test 0.635N0f16 === N0f16(0.635)
+
+    @test_throws ArgumentError 1.1N0f8
+
+    @test wrapping_mul(0.635, N0f8) === N0f8(0.635)
+    @test wrapping_mul(1.635, N0f8) === N0f8((1.635 * 255 - 256) / 255)
+    @test saturating_mul(0.635, N0f8) === N0f8(0.635)
+    @test saturating_mul(1.635, N0f8) === N0f8(1.0)
+    @test checked_mul(0.635, N0f8) === N0f8(0.635)
+    @test_throws ArgumentError checked_mul(1.635, N0f8)
+end
+
 @testset "reinterpret/bitstring" begin
     @test reinterpret(N0f8, 0xa2).i  === 0xa2
     @test reinterpret(N6f10, 0x1fa2).i === 0x1fa2
@@ -30,12 +47,6 @@ end
     @test bitstring(reinterpret(N0f8, 0xa2))    === "10100010"
     @test bitstring(reinterpret(N6f10, 0x00a2)) === "0000000010100010"
 
-    @test 0.635N0f8   == N0f8(0.635)
-    @test 0.635N6f10 == N6f10(0.635)
-    @test 0.635N4f12 == N4f12(0.635)
-    @test 0.635N2f14 == N2f14(0.635)
-    @test 0.635N0f16 == N0f16(0.635)
-
     @test N0f8(1.0) == reinterpret(N0f8, 0xff)
     @test N0f8(0.5) == reinterpret(N0f8, 0x80)
     @test N2f14(1.0) == reinterpret(N2f14, 0x3fff)