Create BitIntegers package extension for cross-conversions between types

Project.toml

@@ -10,7 +10,14 @@ projects = ["test"]
 PrecompileTools = "aea7be01-6a6a-4083-8856-8a6e6704d82a"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 
+[weakdeps]
+BitIntegers = "c3b6d118-76ef-56ca-8cc7-ebb389d030a1"
+
+[extensions]
+BitIntegersExt = "BitIntegers"
+
 [compat]
+BitIntegers = "0.3"
 PrecompileTools = "1"
 Random = "1"
 julia = "1.10"

README.md

@@ -128,6 +128,15 @@ const Int7_8 = Int7
 
 The signedness of data and storage types are always identical.
 
+When both packages are loaded, a package extension enables checked conversion
+from emulated integers to BitIntegers types, including user-defined types from
+`@define_integers`.
+
+```jldoctest usage
+julia> Int256(UInt3(7))
+7
+```
+
 If you want to `@emulate` multiple types, you can simply provide multiple arguments to the macro with regular macro syntax:
 
 ```jldoctest usage

ext/BitIntegersExt.jl

@@ -0,0 +1,8 @@
+module BitIntegersExt
+
+using EmulatedBitIntegers: EmulatedInteger
+using BitIntegers: AbstractBitSigned, AbstractBitUnsigned
+
+(::Type{Target})(value::EmulatedInteger) where {Target<:Union{AbstractBitSigned, AbstractBitUnsigned}} = Target(value[])
+
+end

test/bitintegers.jl

@@ -0,0 +1,24 @@
+@define_integers 24 ConversionInt24 ConversionUInt24
+
+@testset "BitIntegers conversion" begin
+    @emulate Int3 UInt3 Int3_128 UInt3_128 Int129 UInt129
+
+    for Source in (Int3, UInt3, Int3_128, UInt3_128, Int129, UInt129)
+        for Target in (Int256, UInt256, Int512, UInt512, Int1024, UInt1024, ConversionInt24, ConversionUInt24)
+            for value in (typemin(Source), zero(Source), one(Source), typemax(Source))
+                if typemin(Target) <= BigInt(value[]) <= typemax(Target)
+                    expected = Target(value[])
+                    @test (@inferred Target(value)) === expected
+                    @test (@inferred convert(Target, value)) === expected
+                else
+                    @test_throws InexactError Target(value)
+                    @test_throws InexactError convert(Target, value)
+                end
+            end
+        end
+    end
+
+    @test Int256(Int3(1)) === Int256(1)
+    extension = Base.get_extension(EmulatedBitIntegers, :BitIntegersExt)
+    @test isempty(Test.detect_ambiguities(EmulatedBitIntegers, BitIntegers, extension))
+end

test/runtests.jl

@@ -18,6 +18,7 @@ values(x) = x |> fieldvalues |> collect
 include("comparisons.jl")
 include("sums.jl")
 include("broadcasting.jl")
+include("bitintegers.jl")
 
 # ============================================================================
 # Static analysis