Usage example

[roshii]

Hi,

Would you please provide an example or two demonstrating how to get the hash of a string ?

See here after how I did proceed.

julia> str = "hello"
"hello"

julia> mmhash32(sizeof(str), pointer(str), 0%UInt32)
ERROR: MethodError: no method matching fmix(::Int64)
Closest candidates are:
  fmix(::UInt32) at /home/simon/Projects/MurmurHash3.jl/src/MurmurHash3.jl:258
  fmix(::UInt64) at /home/simon/Projects/MurmurHash3.jl/src/MurmurHash3.jl:31
Stacktrace:
 [1] mmhash32(::Int64, ::Ptr{UInt8}, ::UInt32) at /home/simon/Projects/MurmurHash3.jl/src/MurmurHash3.jl:273
 [2] top-level scope at none:0

Thanks upfront!

[roshii]

Changing mhblock to @inline (h1, k1) = rotl13(xor(h1, rotl15(k1 * d1) * d2)) * 0x00000005 + 0xe6546b64 solves the above issue but doesn't deliver expected result for MurmurHash3 32-bit unsigned

[ScottPJones]

Ah, sorry. Just saw this. What is versioninfo() on the platform you are running on?
I hadn't ever tested using MurmurHash3 outside of the Strs.jl (or StrBase.jl) package(s).
If you want hash of a string using one of the string types in the Strs package, just call hash.

[ScottPJones]

Just use the hash function from Julia Base to get the hash value of any string.
There is documentation at the REPL.

[roshii]

Thanks for the above.

Just use the hash function from Julia Base to get the hash value of any string.

Unfortunately, Base.hash implements the 128 bit version of MurmurHash3 whereas I do need its 32-bit version.

Meanwhile, I did manage to modify Murmur3.jl package to get the expected result for a 32-bit hash - similar to SMHasher reference implementation. See different hashing results here after.

julia> str = "Hello World"
"Hello World"

julia> hash(str)
0x9c427f8f448ad93f

julia> mmhash32(sizeof(str), pointer(str), 0%UInt32)
0xf71c2877

julia> Int(ans)
4145817719

julia> Murmur3.hash32(str)
427197390

As you can see, Base.hash returns a 64-bit hash and your implementation does return a 32-bit hash but not what it should be...

Either I do not call mmhash32 correctly, either there is something wrong with it. I will try using Str type to make it work but regardless, it would be nice if MurmurHash3.jl could handle String as well :)

For the record:

julia> versioninfo()
Julia Version 1.1.0
Commit 80516ca202 (2019-01-21 21:24 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, skylake)
Environment:
  JULIA_EDITOR = atom  -a
  JULIA_NUM_THREADS = 2

[roshii]

See here after result of mmhash32 using Str type.
It has exact same behavior as with String type.

julia> str = StrBase.Str("Hello World")
"Hello World"

julia> MurmurHash3.mmhash32(sizeof(str), pointer(str), 0%UInt32)
ERROR: MethodError: no method matching rotl(::Int64, ::Int64)
Closest candidates are:
  rotl(::Unsigned, ::Any) at /home/simon/.julia/packages/MurmurHash3/6widu/src/MurmurHash3.jl:20
Stacktrace:
 [1] mhblock at /home/simon/.julia/packages/MurmurHash3/6widu/src/MurmurHash3.jl:247 [inlined]
 [2] mhbody at /home/simon/.julia/packages/MurmurHash3/6widu/src/MurmurHash3.jl:264 [inlined]
 [3] mmhash32(::Int64, ::Ptr{UInt8}, ::UInt32) at /home/simon/.julia/packages/MurmurHash3/6widu/src/MurmurHash3.jl:271
 [4] top-level scope at none:0

[ScottPJones]

OK, I hadn't spent much time on mmhash32, since I was only using it for 32-bit platforms, and didn't test it on 64-bit platforms.
I'll take a look, as well as look at adding support calling it with a String type.