1 //------------------------------------------------------------------------------
2 // GB_AxB_saxpy3_coarseGus_notM_phase1: symbolic coarse Gustavson, with !M
3 //------------------------------------------------------------------------------
4 
5 // SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2021, All Rights Reserved.
6 // SPDX-License-Identifier: Apache-2.0
7 
8 //------------------------------------------------------------------------------
9 
10 {
11     // Initially, Hf [...] < mark for all of Hf.
12 
13     // Hf [i] < mark    : M(i,j)=0, C(i,j) is not yet seen.
14     // Hf [i] == mark   : M(i,j)=1, so C(i,j) is ignored.
15     // Hf [i] == mark+1 : M(i,j)=0, and C(i,j) has been seen.
16 
17     for (int64_t kk = kfirst ; kk <= klast ; kk++)
18     {
19         GB_GET_B_j ;            // get B(:,j)
20         Cp [kk] = 0 ;
21 
22         //----------------------------------------------------------------------
23         // special case when B(:,j) is empty
24         //----------------------------------------------------------------------
25 
26         #if ( GB_B_IS_SPARSE || GB_B_IS_HYPER )
27         if (bjnz == 0) continue ;
28         #endif
29 
30         //----------------------------------------------------------------------
31         // get M(:,j) and scatter it into the Hf workspace
32         //----------------------------------------------------------------------
33 
34         GB_GET_M_j ;                                // get M(:,j)
35         mark += 2 ;
36         const int64_t f0 = mark ;
37         const int64_t f1 = mark+1 ;
38         GB_SCATTER_M_j (pM_start, pM_end, f0) ;     // scatter M(:,j)
39 
40         //----------------------------------------------------------------------
41         // count nnz in C(:,j)
42         //----------------------------------------------------------------------
43 
44         int64_t cjnz = 0 ;
45         for ( ; pB < pB_end ; pB++)     // scan B(:,j)
46         {
47             GB_GET_B_kj_INDEX ;         // get k of B(k,j)
48             GB_GET_A_k ;                // get A(:,k)
49             // scan A(:,k)
50             for (int64_t pA = pA_start ; pA < pA_end ; pA++)
51             {
52                 GB_GET_A_ik_INDEX ;     // get index i of A(i,k)
53                 if (Hf [i] < f0)        // if true, M(i,j) is 0
54                 {
55                     Hf [i] = f1 ;       // flag C(i,j) as seen
56                     cjnz++ ;            // C(i,j) is a new entry
57                 }
58             }
59         }
60         Cp [kk] = cjnz ;                // count the entries in C(:,j)
61     }
62 }
63 
64