stubmpi.h

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#ifndef MADNESS_STUBMPI_H
#define MADNESS_STUBMPI_H

#include <cstddef>
#include <cstdlib>
#include <cstring>
#include <madness/world/worldtime.h>

typedef int MPI_Group;
typedef int MPI_Request;
typedef struct MPI_Status {
    int count;
    int cancelled;
    int MPI_SOURCE;
    int MPI_TAG;
    int MPI_ERROR;

} MPI_Status;
#define MPI_STATUS_IGNORE ((MPI_Status *)1)
#define MPI_STATUSES_IGNORE ((MPI_Status *)1)

typedef int MPI_Comm;
#define MPI_COMM_WORLD (0x44000000)
#define MPI_UNDEFINED      (-32766)

/* MPI's error classes */
/* these constants are consistent with MPICH2 mpi.h */
#define MPI_SUCCESS          0      /* Successful return code */
#define MPI_ERR_COMM         5      /* Invalid communicator */
#define MPI_ERR_ARG         12      /* Invalid argument */
#define MPI_MAX_ERROR_STRING 1024

/* Results of the compare operations. */
#define MPI_IDENT     0
#define MPI_CONGRUENT 1
#define MPI_SIMILAR   2
#define MPI_UNEQUAL   3

/* MPI null objects */
#define MPI_COMM_NULL       ((MPI_Comm)0x04000000)
#define MPI_OP_NULL         ((MPI_Op)0x18000000)
#define MPI_GROUP_NULL      ((MPI_Group)0x08000000)
#define MPI_DATATYPE_NULL   ((MPI_Datatype)0x0c000000)
#define MPI_REQUEST_NULL    ((MPI_Request)0x2c000000)
#define MPI_ERRHANDLER_NULL ((MPI_Errhandler)0x14000000)

/* MPI thread support levels */
/* these constants are consistent with MPICH2 mpi.h */
#define MPI_THREAD_SINGLE     0
#define MPI_THREAD_FUNNELED   1
#define MPI_THREAD_SERIALIZED 2
#define MPI_THREAD_MULTIPLE   3

/* these constants are consistent with MPICH2 mpi.h */
#define MPI_IN_PLACE   ((void *) -1)
#define MPI_PROC_NULL  -1
#define MPI_ANY_SOURCE -2
#define MPI_ANY_TAG    -1

/* MPI data types */
/* these constants are consistent with MPICH2 mpi.h */
typedef int MPI_Datatype;
#define MPI_CHAR               ((MPI_Datatype)0x4c000101)
#define MPI_SIGNED_CHAR        ((MPI_Datatype)0x4c000118)
#define MPI_UNSIGNED_CHAR      ((MPI_Datatype)0x4c000102)
#define MPI_BYTE               ((MPI_Datatype)0x4c00010d)
#define MPI_WCHAR              ((MPI_Datatype)0x4c00040e)
#define MPI_SHORT              ((MPI_Datatype)0x4c000203)
#define MPI_UNSIGNED_SHORT     ((MPI_Datatype)0x4c000204)
#define MPI_INT                ((MPI_Datatype)0x4c000405)
#define MPI_UNSIGNED           ((MPI_Datatype)0x4c000406)
#define MPI_LONG               ((MPI_Datatype)0x4c000807)
#define MPI_UNSIGNED_LONG      ((MPI_Datatype)0x4c000808)
#define MPI_FLOAT              ((MPI_Datatype)0x4c00040a)
#define MPI_DOUBLE             ((MPI_Datatype)0x4c00080b)
#define MPI_LONG_DOUBLE        ((MPI_Datatype)0x4c00100c)
#define MPI_LONG_LONG_INT      ((MPI_Datatype)0x4c000809)
#define MPI_UNSIGNED_LONG_LONG ((MPI_Datatype)0x4c000819)
#define MPI_LONG_LONG          ((MPI_Datatype)0x4c000809)

/* MPI Reduction operation */
/* these constants are consistent with MPICH2 mpi.h */
typedef int MPI_Op;
#define MPI_MAX     ((MPI_Op)0x58000001)
#define MPI_MIN     ((MPI_Op)0x58000002)
#define MPI_SUM     ((MPI_Op)0x58000003)
#define MPI_PROD    ((MPI_Op)0x58000004)
#define MPI_LAND    ((MPI_Op)0x58000005)
#define MPI_BAND    ((MPI_Op)0x58000006)
#define MPI_LOR     ((MPI_Op)0x58000007)
#define MPI_BOR     ((MPI_Op)0x58000008)
#define MPI_LXOR    ((MPI_Op)0x58000009)
#define MPI_BXOR    ((MPI_Op)0x5800000a)
#define MPI_MINLOC  ((MPI_Op)0x5800000b)
#define MPI_MAXLOC  ((MPI_Op)0x5800000c)
#define MPI_REPLACE ((MPI_Op)0x5800000d)

/* FIXME This function should agree with http://www.mpich.org/static/docs/v3.1/www3/MPI_Group_translate_ranks.html */
#warning This is not equivalent to the interface defined by the MPI standard!
inline int MPI_Group_translate_ranks(const MPI_Group&, int n, const int*, const MPI_Group&, int* ranks2) {
    *ranks2 = 0;
    return MPI_SUCCESS;
}

/* TODO The NO-OP implementation of may not be adequate. */
inline int MPI_Group_incl(MPI_Group group, int n, const int ranks[], MPI_Group *newgroup) {
    return MPI_SUCCESS;
}

/* TODO The NO-OP implementation may not be adequate. */
inline int MPI_Group_free(MPI_Group *group) {
    return MPI_SUCCESS;
}

// Initialization and finalize functions
inline int MPI_Init(int *, char ***) { return MPI_SUCCESS; }
inline int MPI_Init_thread(int *, char ***, int, int *provided) { *provided = MPI_THREAD_SERIALIZED; return MPI_SUCCESS; }
inline int MPI_Initialized(int* flag) { *flag = 1; return MPI_SUCCESS; }
inline int MPI_Finalize() { return MPI_SUCCESS; }
inline int MPI_Finalized(int* flag) { *flag = 1; return MPI_SUCCESS; }
inline int MPI_Query_thread(int *provided) { *provided = MPI_THREAD_SERIALIZED; return MPI_SUCCESS; }

// Buffer functions (do nothing since no messages may be sent)
inline int MPI_Buffer_attach(void*, int) { return MPI_SUCCESS; }
inline int MPI_Buffer_detach(void* buffer, int* size) { return MPI_SUCCESS; }

inline int MPI_Test(MPI_Request *, int *flag, MPI_Status *) {
    *flag = 0;
    return MPI_SUCCESS;
}

inline int MPI_Testany(int, MPI_Request[], int* index, int *flag, MPI_Status*) {
    *index = MPI_UNDEFINED;
    *flag = 0;
    return MPI_SUCCESS;
}

inline int MPI_Testsome(int, MPI_Request*, int *outcount, int*, MPI_Status*) {
    *outcount = MPI_UNDEFINED;
    return MPI_SUCCESS;
}

inline int MPI_Get_count(MPI_Status *, MPI_Datatype, int *count) {
    *count = 0;
    return MPI_SUCCESS;
}

// Communicator rank and size
inline int MPI_Comm_rank(MPI_Comm, int* rank) { *rank = 0; return MPI_SUCCESS; }
inline int MPI_Comm_size(MPI_Comm, int* size) { *size = 1; return MPI_SUCCESS; }

// There is only one node so sending messages is not allowed. Always return MPI_ERR_COMM
inline int MPI_Isend(void*, int, MPI_Datatype, int, int, MPI_Comm, MPI_Request *) { return MPI_ERR_COMM; }
inline int MPI_Send(void*, int, MPI_Datatype, int, int, MPI_Comm) { return MPI_ERR_COMM; }
inline int MPI_Bsend(void*, int, MPI_Datatype, int, int, MPI_Comm) { return MPI_ERR_COMM; }
inline int MPI_Irecv(void*, int, MPI_Datatype, int, int, MPI_Comm, MPI_Request*) { return MPI_ERR_COMM; }
inline int MPI_Recv(void*, int, MPI_Datatype, int, int, MPI_Comm, MPI_Status*) { return MPI_ERR_COMM; }

// Bcast does nothing but return MPI_SUCCESS
inline int MPI_Bcast(void*, int, MPI_Datatype, int, MPI_Comm) { return MPI_SUCCESS; }

// Reduce does memcpy and returns MPI_SUCCESS
inline int MPI_Reduce(void *sendbuf, void *recvbuf, int count, MPI_Datatype, MPI_Op, int, MPI_Comm) {
    if(sendbuf != MPI_IN_PLACE) std::memcpy(recvbuf, sendbuf, count);
    return MPI_SUCCESS;
}
inline int MPI_Allreduce(void *sendbuf, void *recvbuf, int count, MPI_Datatype, MPI_Op, MPI_Comm) {
    if(sendbuf != MPI_IN_PLACE) std::memcpy(recvbuf, sendbuf, count);
    return MPI_SUCCESS;
}

inline int MPI_Comm_get_attr(MPI_Comm, int, void*, int*) { return MPI_ERR_COMM; }

inline int MPI_Abort(MPI_Comm, int code) { exit(code); return MPI_SUCCESS; }

inline int MPI_Barrier(MPI_Comm) { return MPI_SUCCESS; }

inline int MPI_Comm_create(MPI_Comm,  MPI_Group, MPI_Comm *newcomm) {
    *newcomm = MPI_COMM_NULL;
    return MPI_SUCCESS;
}

inline int MPI_Comm_group(MPI_Comm, MPI_Group* group) {
    *group = MPI_GROUP_NULL;
    return MPI_SUCCESS;
}

inline int MPI_Comm_free(MPI_Comm * comm) {
    *comm = MPI_COMM_NULL;
    return MPI_SUCCESS;
}

inline int MPI_Comm_compare(MPI_Comm comm1, MPI_Comm comm2, int *result) {
    if (comm1 == comm2) {
        *result = MPI_IDENT;
    } else {
        *result = MPI_UNEQUAL;
    }
    return MPI_SUCCESS;
}


inline int MPI_Error_string(int errorcode, char *string, int *resultlen) {
    switch(errorcode) {
        case MPI_SUCCESS:
            *resultlen = 8;
            std::strncpy(string, "Success", *resultlen);
            break;
        case MPI_ERR_COMM:
            *resultlen = 21;
            std::strncpy(string, "Invalid communicator", *resultlen);
            break;
        case MPI_ERR_ARG:
            *resultlen = 17;
            std::strncpy(string, "Invalid argument", *resultlen);
            break;
        default:
            return MPI_ERR_ARG;
            break;
    }

    return MPI_SUCCESS;
}

inline double MPI_Wtime() { return madness::wall_time(); }

#endif