mpi.impala

type size_t = u64;

type MPI_Comm = &();
type MPI_Datatype = &();
type MPI_Op = &();
type MPI_Request = &();
type MPI_Status = &mut [i8];
type MPI_Buf = &[i8];
type MPI_MutBuf = &mut [i8];

extern "C" {
    // fn MPI_Init(&i32, &[&[u8]]) -> i32;
    fn MPI_init() -> i32;
    fn MPI_Comm_size(MPI_Comm, &mut i32) -> i32;
    fn MPI_Comm_rank(MPI_Comm, &mut i32) -> i32;
    fn MPI_Allreduce(MPI_Buf, MPI_MutBuf, i32, MPI_Datatype, MPI_Op, MPI_Comm) -> i32;
    fn MPI_Send(MPI_Buf, i32, MPI_Datatype, i32, i32, MPI_Comm) -> i32;
    fn MPI_Recv(MPI_MutBuf, i32, MPI_Datatype, i32, i32, MPI_Comm, MPI_Status) -> i32;
    fn MPI_Isend_ex(MPI_Buf, i32, MPI_Datatype, i32, i32, MPI_Comm, i32) -> i32;
    fn MPI_Irecv_ex(MPI_MutBuf, i32, MPI_Datatype, i32, i32, MPI_Comm, i32) -> i32;
    fn MPI_Wait(&MPI_Request, MPI_Status) -> i32;
    fn MPI_Waitall_ex(i32) -> i32;
    fn MPI_Probe(i32, i32, MPI_Comm, MPI_Status) -> i32;
    fn MPI_Get_count(MPI_Status, MPI_Datatype, &mut i32) -> i32;
    fn MPI_Gather(MPI_Buf, i32, MPI_Datatype, MPI_MutBuf, i32, MPI_Datatype, i32, MPI_Comm) -> i32;
    fn MPI_Barrier(MPI_Comm, &MPI_Request) -> i32;
    fn MPI_Wtime() -> f64;
    fn MPI_Finalize() -> i32;
    // wrappers in mpi.cpp for getting MPI constants
    fn get_mpi_comm_world() -> MPI_Comm;
    fn get_mpi_int() -> MPI_Datatype;
    fn get_mpi_int64() -> MPI_Datatype;
    fn get_mpi_double() -> MPI_Datatype;
    fn get_mpi_float() -> MPI_Datatype;
    fn get_mpi_max() -> MPI_Op;
    fn get_mpi_sum() -> MPI_Op;
    fn get_mpi_status_ignore() -> MPI_Status;
    fn get_mpi_cart_neighborhood(i32, i32, i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32) -> ();
    fn sync_ghost_layer_loop(i32, MPI_Buf, MPI_MutBuf, &[i32], &[i32], &[i32], &[i32], &[i32], &[i32]) -> ();
}

struct MPIComms {
    world : MPI_Comm,
}

struct MPIOps {
    max : MPI_Op,
    sum : MPI_Op,
}

// TODO should be autogenerated, differs for other MPI implementations (e.g. MPICH)
struct MPIStatus {
    source : i32,
    tag : i32,
    error : i32,
    // internal to openmpi, do not access
    _cancelled : i32,
    _ucount : u64
}

struct MPIStatuses {
    ignore : &mut MPIStatus,
}

struct MPI {
    comms : MPIComms,
    ops : MPIOps,
    status : MPIStatuses,
    int_t : MPI_Datatype,
    double_t : MPI_Datatype,
    float_t : MPI_Datatype,
    int64_t: MPI_Datatype,
    init : fn() -> i32,
    comm_size : fn(MPI_Comm, &mut i32) -> i32,
    comm_rank : fn(MPI_Comm, &mut i32) -> i32,
    cart: fn(i32, i32, i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32, &mut i32) -> (),
    allreduce : fn(MPI_Buf, MPI_MutBuf, i32, MPI_Datatype, MPI_Op, MPI_Comm) -> i32,
    send : fn(MPI_Buf, i32, MPI_Datatype, i32, i32, MPI_Comm) -> i32,
    recv : fn(MPI_MutBuf, i32, MPI_Datatype, i32, i32, MPI_Comm, &mut MPIStatus) -> i32,
    isend : fn(MPI_Buf, i32, MPI_Datatype, i32, i32, MPI_Comm, i32) -> i32,
    irecv : fn(MPI_MutBuf, i32, MPI_Datatype, i32, i32, MPI_Comm, i32) -> i32,
    wait : fn(&MPI_Request, &mut MPIStatus) -> i32,
    wait_all : fn(i32) -> i32,
    probe: fn(i32, i32, MPI_Comm, &mut MPIStatus) -> i32,
    get_count: fn(&mut MPIStatus, MPI_Datatype, &mut i32) -> i32,
    gather: fn(MPI_Buf, i32, MPI_Datatype, MPI_MutBuf, i32, MPI_Datatype, i32, MPI_Comm) -> i32,
    barrier : fn(MPI_Comm, &MPI_Request) -> i32,
    wtime : fn() -> f64,
    finalize : fn() -> i32,
}

fn get_world_size() -> i32 {
    let mpih = mpi();
    let mut world_size: i32;
    mpih.comm_size(mpih.comms.world, &mut world_size);
    world_size
}

fn get_process_rank() -> i32 {
    let mpih = mpi();
    let mut rank: i32;
    mpih.comm_rank(mpih.comms.world, &mut rank);
    rank
}

fn barrier() -> () {
    let mpih = mpi();
    let mut request: MPI_Request;
    mpih.barrier(mpih.comms.world, &mut request);
}

fn @mpi() -> MPI {
    MPI {
        comms : MPIComms {
            world : get_mpi_comm_world(),
        },
        ops : MPIOps {
            max : get_mpi_max(),
            sum : get_mpi_sum(),
        },
        status : MPIStatuses {
            ignore : get_mpi_status_ignore() as &mut MPIStatus,
        },
        double_t : get_mpi_double(),
        int_t : get_mpi_int(),
        int64_t : get_mpi_int64(),
        float_t : get_mpi_float(),
        init : MPI_init,
        comm_size : MPI_Comm_size,
        comm_rank : MPI_Comm_rank,
        cart: get_mpi_cart_neighborhood,
        allreduce : MPI_Allreduce,
        send : MPI_Send,
        recv : @|buf, count, datatype, source, tag, comm, status| {
            MPI_Recv(buf, count, datatype, source, tag, comm, status as MPI_Status)
        },
        isend : MPI_Isend_ex,
        irecv : MPI_Irecv_ex,
        wait : @|request, status| {
            MPI_Wait(request, status as MPI_Status)
        },
        wait_all : @|count| {
            MPI_Waitall_ex(count)
        },
        probe: @|source, tag, comm, status| {
            MPI_Probe(source, tag, comm, status as MPI_Status)
        },
        get_count: @|status, datatype, count| {
            MPI_Get_count(status as MPI_Status, datatype, count)
        },
        gather: MPI_Gather,
        barrier : MPI_Barrier,
        wtime : MPI_Wtime,
        finalize : MPI_Finalize,
    }
}

;