Fix length for StepRange

Author: timholy

src/FixedPointNumbers.jl

@@ -8,7 +8,7 @@ import Base: ==, <, <=, -, +, *, /, ~, isapprox,
              div, fld, rem, mod, mod1, fld1, min, max, minmax,
              rand
 
-using Base.Checked: checked_add, checked_sub
+using Base.Checked: checked_add, checked_sub, checked_div
 
 using Base: @pure
 
@@ -142,6 +142,21 @@ for f in (:+, :-, :rem, :mod, :mod1, :min, :max)
     end
 end
 
+function Base.unsafe_length(r::StepRange{X,Y}) where {X<:FixedPoint{<:ShorterThanInt}, Y<:FixedPoint{<:ShorterThanInt}}
+    start, step, stop = reinterpret(r.start), reinterpret(r.step), reinterpret(r.stop)
+    return div(Int(stop) - Int(start) + Int(step), Int(step))
+end
+function Base.unsafe_length(r::StepRange{X,Y}) where {X<:FixedPoint, Y<:FixedPoint}
+    start, step, stop = reinterpret(r.start), reinterpret(r.step), reinterpret(r.stop)
+    return div((stop - start) + step, step)
+end
+Base.length(r::StepRange{X,Y}) where {X<:FixedPoint{<:ShorterThanInt}, Y<:FixedPoint{<:ShorterThanInt}} =
+    Base.unsafe_length(r)
+function Base.length(r::StepRange{X,Y}) where {X<:FixedPoint, Y<:FixedPoint}
+    start, step, stop = reinterpret(r.start), reinterpret(r.step), reinterpret(r.stop)
+    return checked_div(checked_add(checked_sub(stop, start), step), step)
+end
+
 # Printing. These are used to generate type-symbols, so we need them
 # before we include any files.
 function showtype(io::IO, ::Type{X}) where {X <: FixedPoint}

test/fixed.jl

@@ -122,6 +122,20 @@ end
     @test length(typemin(QInt1):typemax(QInt1)) == typemax(Int)
 end
 
+@testset "step range" begin
+    r = typemin(Q0f7):eps(Q0f7):typemax(Q0f7)
+    counter = 0
+    for x in r
+        counter += 1
+    end
+    @test counter == 256
+    @test length(r) == 256
+    QInt1 = Fixed{Int,1}
+    @test length(QInt1(0):eps(QInt1):typemax(QInt1)-eps(QInt1)) == typemax(Int)
+    @test Base.unsafe_length(typemin(QInt1):eps(QInt1):typemax(QInt1)-eps(QInt1)) == -1
+    @test_throws OverflowError length(QInt1(-1):eps(QInt1):typemax(QInt1)-eps(QInt1))
+end
+
 @testset "reductions" begin
     F8 = Fixed{Int8,8}
     a = F8[0.498, 0.1]

test/normed.jl

@@ -318,8 +318,11 @@ end
     end
     @test counter == 256
     @test length(N0f8(0):eps(N0f8):N0f8(1)) == 256
-    r = reinterpret(N0f8, 0x01):reinterpret(N0f8, 0x01):reinterpret(N0f8, convert(UInt8, 48))
+    r = reinterpret(N0f8, 0x01):reinterpret(N0f8, 0x01):reinterpret(N0f8, UInt8(48))
     @test length(r) == 48
+    NInt1 = Normed{UInt,1}
+    @test length(NInt1(0):NInt1(1):typemax(NInt1)-oneunit(NInt1)) == typemax(UInt)
+    @test_throws OverflowError length(NInt1(0):NInt1(1):typemax(NInt1))
 end
 
 @testset "Promotion within Normed" begin