Add ROOTIOBuffer

Author: oschulz

src/UpROOT.jl

@@ -14,6 +14,7 @@ uproot = PyNULL()
 
 include("testdata.jl")
 include("pywrappers.jl")
+include("rootio.jl")
 include("opaque.jl")
 include("pyjlconv.jl")
 include("tdirectory.jl")

src/rootio.jl

@@ -0,0 +1,132 @@
+# This file is a part of UpROOT.jl, licensed under the MIT License (MIT).
+
+const kByteCountMask = UInt32(0x40000000)
+const kByteCountMask_UInt16 = UInt16(kByteCountMask >> 16)
+
+
+struct ROOTIOBuffer{T}
+    buffer::Base.GenericIOBuffer{T}
+end
+
+ROOTIOBuffer(data::AbstractVector{UInt8}) = ROOTIOBuffer(IOBuffer(data))
+
+
+Base.eof(io::ROOTIOBuffer) = eof(io.buffer)
+
+
+function Base.read(io::ROOTIOBuffer, ::Type{String})
+    short_len = read(io.buffer, UInt8)
+    len = (short_len < 0xff) ? UInt32(short_len) : read(io.buffer, UInt32)
+    String(read(io.buffer, len))
+end
+
+
+function Base.read(io::ROOTIOBuffer, ::Type{T}) where {T<:Real}
+    x::T = read(io.buffer, T)
+    if sizeof(T) > 1
+        x = ntoh(x)
+    end
+    x
+end
+
+
+function Base.read(io::ROOTIOBuffer, ::Type{Vector{T}}) where {T<:Real}
+    len = read(io, UInt32)
+    A = Vector{T}(undef, len)
+    read!(io.buffer, A)
+    if sizeof(T) > 1
+        A .= ntoh.(A)
+    end
+    A
+end
+
+
+
+struct ROOTClassHeader
+    classname::String
+end
+
+function Base.read(io::ROOTIOBuffer, ::Type{ROOTClassHeader})
+    classname = read(io, String)
+    padding = read(io, UInt8)
+    ROOTClassHeader(classname)
+end
+
+
+
+struct ROOTClassVersion
+    nbytes::UInt32
+    version::Int16
+end
+
+function Base.read(io::ROOTIOBuffer, ::Type{ROOTClassVersion})
+    a = read(io, UInt16)
+
+    if a & kByteCountMask_UInt16 > 0
+        # byte count available
+        b = read(io, UInt32)
+        cnt = (UInt32(a & ~kByteCountMask_UInt16) << 16 | b >> 16)
+        version = b % Int16
+        bytecount = cnt - sizeof(version)
+        ROOTClassVersion(bytecount, version)
+    else
+        ROOTClassVersion(0, signed(a))
+    end
+end
+
+
+
+struct TObjectContent
+    fUniqueID::UInt32
+    fBits::UInt32
+end
+
+function Base.read(io::ROOTIOBuffer, ::Type{TObjectContent})
+    ver = read(io, ROOTClassVersion)
+    @assert ver.nbytes == 0
+    @assert ver.version == 1
+    fUniqueID = read(io, UInt32)
+    fBits = read(io, UInt32)
+    TObjectContent(fUniqueID, fBits)
+end
+
+
+
+struct TNamedContent{S<:AbstractString}
+    tobject::TObjectContent
+    fName::S
+    fTitle::S
+end
+
+function Base.read(io::ROOTIOBuffer, ::Type{TNamedContent})
+    ver = read(io, ROOTClassVersion)
+    @assert ver.version == 1
+    tobject = read(io, TObjectContent)
+    fName = read(io, String)
+    fTitle = read(io, String)
+    TNamedContent(tobject, fName, fTitle)
+end
+
+
+
+struct TClonesArrayHeader{S<:AbstractString}
+    tobject::TObjectContent
+    fName::S
+    fClass::S
+    nobjects::Int
+    fLowerBound::Int
+end
+
+function Base.read(io::ROOTIOBuffer, ::Type{TClonesArrayHeader})
+    ver = read(io, ROOTClassVersion)
+    @assert ver.version == 4
+    tobject = read(io, TObjectContent)
+    fName = read(io, String)
+    fClass = read(io, String)
+    nobjects = read(io, Int32)
+    fLowerBound = read(io, Int32)
+
+    # assuming CanBypassStreamer() is false:
+    nch = read(io, Int8)
+    TClonesArrayHeader(tobject, fName, fClass, Int(nobjects), Int(fLowerBound))
+end