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//------------------------------------------------------------------------------
// GxB_Matrix_Iterator: seek to a specific entry for a matrix iterator
//------------------------------------------------------------------------------
// SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
#include "GB.h"
#include "GB_search_for_vector_template.c"
//------------------------------------------------------------------------------
// GxB_Matrix_Iterator_attach: attach an entry iterator to a matrix
//------------------------------------------------------------------------------
// On input, the iterator must already exist, having been created by
// GxB_Iterator_new.
// GxB_Matrix_Iterator_attach attaches an entry iterator to a matrix. If the
// iterator is already attached to a matrix, it is detached and then attached
// to the given matrix A.
// The following error conditions are returned:
// GrB_NULL_POINTER: if the iterator or A are NULL.
// GrB_INVALID_OBJECT: if the matrix A is invalid.
// GrB_OUT_OF_MEMORY: if the method runs out of memory.
// If successful, the entry iterator is attached to the matrix, but not to any
// specific entry. Use GxB_Matrix_Iterator_*seek* to move the iterator to a
// particular entry.
GrB_Info GxB_Matrix_Iterator_attach
(
GxB_Iterator iterator,
GrB_Matrix A,
GrB_Descriptor desc
)
{
return (GB_Iterator_attach (iterator, A, GxB_NO_FORMAT, desc)) ;
}
//------------------------------------------------------------------------------
// GxB_Matrix_Iterator_getpmax: return the range of the iterator
//------------------------------------------------------------------------------
// On input, the entry iterator must be already attached to a matrix via
// GxB_Matrix_Iterator_attach; results are undefined if this condition is not
// met.
// Entries in a matrix are given an index p, ranging from 0 to pmax-1, where
// pmax >= nvals(A). For sparse, hypersparse, and full matrices, pmax is equal
// to nvals(A). For an m-by-n bitmap matrix, pmax=m*n, or pmax=0 if the
// matrix has no entries.
GrB_Index GxB_Matrix_Iterator_getpmax (GxB_Iterator iterator)
{
return (iterator->pmax) ;
}
//------------------------------------------------------------------------------
// GB_full_position: find the vector containing p for a full/bitmap matrix
//------------------------------------------------------------------------------
static inline GrB_Info GB_full_position (GxB_Iterator iterator)
{
iterator->k = iterator->p / iterator->avlen ;
iterator->pstart = iterator->k * iterator->avlen ;
iterator->pend = iterator->pstart + iterator->avlen ;
return (GrB_SUCCESS) ;
}
//------------------------------------------------------------------------------
// GB_check_for_end_of_vector: move to next vector if current vector is done
//------------------------------------------------------------------------------
static inline GrB_Info GB_check_for_end_of_vector (GxB_Iterator iterator)
{
// move to the next vector if p has reached the end of the current vector
switch (iterator->A_sparsity)
{
default:
case GxB_SPARSE :
case GxB_HYPERSPARSE :
{
if (iterator->p >= iterator->pend)
{
// the kth vector is done; move to the next non-empty vector
iterator->pstart = iterator->pend ;
iterator->k++ ;
while (iterator->Ap [iterator->k+1] == iterator->pend)
{
// iterator->k is an empty vector; move to the next one
iterator->k++ ;
ASSERT (iterator->k < iterator->anvec) ;
}
// iterator->k is now the next non-empty vector
iterator->pend = iterator->Ap [iterator->k+1] ;
return (GrB_SUCCESS) ;
}
}
break ;
case GxB_BITMAP :
{
for ( ; iterator->p < iterator->pmax ; iterator->p++)
{
if (iterator->Ab [iterator->p])
{
// found the next entry; check if it is past the kth vector
if (iterator->p >= iterator->pend)
{
// find the vector of this entry
return (GB_full_position (iterator)) ;
}
return (GrB_SUCCESS) ;
}
}
return (GxB_EXHAUSTED) ;
}
break ;
case GxB_FULL :
{
if (iterator->p >= iterator->pend)
{
// kth vector is done; move to the next vector
iterator->k++ ;
iterator->pstart += iterator->avlen ;
iterator->pend += iterator->avlen ;
}
}
break ;
}
return (GrB_SUCCESS) ;
}
//------------------------------------------------------------------------------
// GxB_Matrix_Iterator_next: move an entry iterator to the next entry
//------------------------------------------------------------------------------
GrB_Info GxB_Matrix_Iterator_next (GxB_Iterator iterator)
{
// move to the next entry
if (++(iterator->p) >= iterator->pmax)
{
// the iterator is exhausted
iterator->p = iterator->pmax ;
return (GxB_EXHAUSTED) ;
}
else
{
// move to next vector if iterator has reached the end of a vector
return (GB_check_for_end_of_vector (iterator)) ;
}
}
//------------------------------------------------------------------------------
// GxB_Matrix_Iterator_seek: seek an entry iterator to any entry
//------------------------------------------------------------------------------
GrB_Info GxB_Matrix_Iterator_seek
(
GxB_Iterator iterator,
GrB_Index p
)
{
if (p >= iterator->pmax)
{
// the iterator is exhausted
iterator->p = iterator->pmax ;
return (GxB_EXHAUSTED) ;
}
else if (p == 0)
{
// seek to the first entry of the first vector A(:,0)
iterator->pstart = 0 ;
iterator->pend = (iterator->Ap != NULL) ?
iterator->Ap [1] : iterator->avlen ;
iterator->p = 0 ;
iterator->k = 0 ;
// move to the next non-empty vector if A(:,0) is empty
return (GB_check_for_end_of_vector (iterator)) ;
}
else
{
// seek to an arbitrary position in the matrix
iterator->p = p ;
switch (iterator->A_sparsity)
{
default:
case GxB_SPARSE :
case GxB_HYPERSPARSE :
{
// find the vector k that contains position p
iterator->k = GB_search_for_vector (p, iterator->Ap,
0, iterator->anvec, iterator->avlen) ;
iterator->pstart = iterator->Ap [iterator->k] ;
iterator->pend = iterator->Ap [iterator->k+1] ;
}
break ;
case GxB_BITMAP :
{
for ( ; iterator->p < iterator->pmax ; iterator->p++)
{
if (iterator->Ab [iterator->p])
{
// found next entry; find the vector that contains it
return (GB_full_position (iterator)) ;
}
}
return (GxB_EXHAUSTED) ;
}
break ;
case GxB_FULL :
{
// find the vector k that contains position p
return (GB_full_position (iterator)) ;
}
break ;
}
}
return (GrB_SUCCESS) ;
}
//------------------------------------------------------------------------------
// GxB_Matrix_Iterator_getp: get the current position of a matrix iterator
//------------------------------------------------------------------------------
// On input, the entry iterator must be already attached to a matrix via
// GxB_Matrix_Iterator_attach, and the position of the iterator must also have
// been defined by a prior call to GxB_Matrix_Iterator_seek or
// GxB_Matrix_Iterator_next. Results are undefined if these conditions are not
// met.
GrB_Index GxB_Matrix_Iterator_getp (GxB_Iterator iterator)
{
return (iterator->p) ;
}
//------------------------------------------------------------------------------
// GxB_Matrix_Iterator_getIndex: get the row and column index of a matrix entry
//------------------------------------------------------------------------------
// On input, the entry iterator must be already attached to a matrix via
// GxB_Matrix_Iterator_attach, and the position of the iterator must also have
// been defined by a prior call to GxB_Matrix_Iterator_seek or
// GxB_Matrix_Iterator_next, with a return value of GrB_SUCCESS. Results are
// undefined if these conditions are not met.
void GxB_Matrix_Iterator_getIndex
(
GxB_Iterator iterator,
GrB_Index *row,
GrB_Index *col
)
{
// get row and column index of current entry, for matrix iterator
switch (iterator->A_sparsity)
{
default:
case GxB_SPARSE :
{
if (iterator->by_col)
{
(*row) = iterator->Ai [iterator->p] ;
(*col) = iterator->k ;
}
else
{
(*row) = iterator->k ;
(*col) = iterator->Ai [iterator->p] ;
}
}
break ;
case GxB_HYPERSPARSE :
{
if (iterator->by_col)
{
(*row) = iterator->Ai [iterator->p] ;
(*col) = iterator->Ah [iterator->k] ;
}
else
{
(*row) = iterator->Ah [iterator->k] ;
(*col) = iterator->Ai [iterator->p] ;
}
}
break ;
case GxB_BITMAP :
case GxB_FULL :
{
if (iterator->by_col)
{
(*row) = iterator->p - iterator->pstart ;
(*col) = iterator->k ;
}
else
{
(*row) = iterator->k ;
(*col) = iterator->p - iterator->pstart ;
}
}
break ;
}
}
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