//------------------------------------------------------------------------------
// GB_mex_subassign_alias: C<C>(:,:) = accum(C(:,:),C)
//------------------------------------------------------------------------------

// SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2020, All Rights Reserved.
// http://suitesparse.com   See GraphBLAS/Doc/License.txt for license.

//------------------------------------------------------------------------------

#include "GB_mex.h"

#define USAGE "C = GB_mex_subassign_alias (C, accum, desc)"

#define FREE_ALL                            \
{                                           \
    GB_MATRIX_FREE (&C) ;                   \
    GrB_Descriptor_free_(&desc) ;           \
    GB_mx_put_global (true, 0) ;            \
}

void mexFunction
(
    int nargout,
    mxArray *pargout [ ],
    int nargin,
    const mxArray *pargin [ ]
)
{

    bool malloc_debug = GB_mx_get_global (true) ;
    GrB_Matrix C = NULL ;
    GrB_Descriptor desc = NULL ;

    // check inputs
    GB_WHERE (USAGE) ;
    if (nargout > 1 || nargin < 2 || nargin > 3)
    {
        mexErrMsgTxt ("Usage: " USAGE) ;
    }

    // get C (make a deep copy)
    #define GET_DEEP_COPY \
    C = GB_mx_mxArray_to_Matrix (pargin [0], "C input", true, true) ;
    #define FREE_DEEP_COPY GB_MATRIX_FREE (&C) ;
    GET_DEEP_COPY ;
    if (C == NULL)
    {
        FREE_ALL ;
        mexErrMsgTxt ("C failed") ;
    }

    // get accum, if present
    bool user_complex = (Complex != GxB_FC64) && (C->type == Complex) ;
    GrB_BinaryOp accum ;
    if (!GB_mx_mxArray_to_BinaryOp (&accum, pargin [1], "accum",
        C->type, user_complex))
    {
        FREE_ALL ;
        mexErrMsgTxt ("accum failed") ;
    }

    // get desc
    if (!GB_mx_mxArray_to_Descriptor (&desc, PARGIN (2), "desc"))
    {
        FREE_ALL ;
        mexErrMsgTxt ("desc failed") ;
    }

    GrB_Index nrows, ncols ;
    GrB_Matrix_nvals (&nrows, C) ;
    GrB_Matrix_nvals (&ncols, C) ;

    // C<C>(:,:) = accum (C(:,:),C)
    METHOD (GxB_Matrix_subassign_(C, C, accum, C,
        GrB_ALL, nrows, GrB_ALL, ncols, desc)) ;

    // return C to MATLAB as a struct and free the GraphBLAS C
    pargout [0] = GB_mx_Matrix_to_mxArray (&C, "C output", true) ;

    FREE_ALL ;
}

