Add optimised fill!(::MutableMemoryView{UInt8}, ::UInt8) (#30)

Author: jakobnissen

Project.toml

@@ -1,6 +1,6 @@
 name = "MemoryViews"
 uuid = "a791c907-b98b-4e44-8f4d-e4c2362c6b2f"
-version = "0.3.5"
+version = "0.3.6"
 authors = ["Jakob Nybo Nissen <jakobnybonissen@gmail.com>"]
 
 [weakdeps]

src/basic.jl

@@ -179,6 +179,17 @@ function Base.copyto!(dst::MutableMemoryView{T}, src::MemoryView{T}) where {T}
     return unsafe_copyto!(dst, src)
 end
 
+function Base.fill!(v::MutableMemoryView{UInt8}, x::Integer)
+    xT = convert(UInt8, x)::UInt8
+    isempty(v) && return v
+    GC.@preserve v @ccall memset(
+        pointer(v)::Ptr{Nothing},
+        Int32(xT)::Cint,
+        (length(v) % UInt)::Csize_t
+    )::Cvoid
+    return v
+end
+
 # Optimised methods that don't boundscheck
 function Base.findnext(p::Function, mem::MemoryView, start::Integer)
     i = Int(start)::Int

test/runtests.jl

@@ -580,6 +580,18 @@ end
     end
 end
 
+@testset "memset" begin
+    @test_throws Exception fill!(ImmutableMemoryView(UInt8[1, 2, 3]), 0x02)
+
+    v = MemoryView(UInt8[1, 2, 3, 4, 5])
+    fill!(v, 0x03)
+    @test v == fill(0x03, length(v))
+
+    v = MemoryView(UInt8[])
+    fill!(v, 0x03)
+    @test isempty(v)
+end
+
 @testset "Iterators.reverse" begin
     for v in Any[AbstractString["abc", "def", ""], Char['a', 'b'], UInt32[], Int16[9, 2, 1]]
         mem = MemoryView(v)