summaryrefslogtreecommitdiffstats
path: root/src/bdd/llb/llb1Sched.c
blob: 51de973ae8b98ce7bfe94a7ca431a3c14dcf898c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
/**CFile****************************************************************

  FileName    [llb1Sched.c]

  SystemName  [ABC: Logic synthesis and verification system.]

  PackageName [BDD based reachability.]

  Synopsis    [Partition scheduling algorithm.]

  Author      [Alan Mishchenko]
  
  Affiliation [UC Berkeley]

  Date        [Ver. 1.0. Started - June 20, 2005.]

  Revision    [$Id: llb1Sched.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]

***********************************************************************/

#include "llbInt.h"

ABC_NAMESPACE_IMPL_START


////////////////////////////////////////////////////////////////////////
///                        DECLARATIONS                              ///
////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////
///                     FUNCTION DEFINITIONS                         ///
////////////////////////////////////////////////////////////////////////

/**Function*************************************************************

  Synopsis    [Swaps two rows.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Llb_MtrSwapColumns( Llb_Mtr_t * p, int iCol1, int iCol2 )
{
    Llb_Grp_t * pGemp;
    char * pTemp;
    int iTemp;
    assert( iCol1 >= 0 && iCol1 < p->nCols );
    assert( iCol2 >= 0 && iCol2 < p->nCols );
    if ( iCol1 == iCol2 )
        return;
    assert( iCol1 != iCol2 );
    // swap col groups
    pGemp = p->pColGrps[iCol1];
    p->pColGrps[iCol1] = p->pColGrps[iCol2];
    p->pColGrps[iCol2] = pGemp;
    // swap col vectors
    pTemp = p->pMatrix[iCol1];
    p->pMatrix[iCol1] = p->pMatrix[iCol2];
    p->pMatrix[iCol2] = pTemp;
    // swap col sums
    iTemp = p->pColSums[iCol1];
    p->pColSums[iCol1] = p->pColSums[iCol2];
    p->pColSums[iCol2] = iTemp;
}

/**Function*************************************************************

  Synopsis    [Find columns which brings as few vars as possible.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Llb_MtrFindBestColumn( Llb_Mtr_t * p, int iGrpStart )
{
    int Cost, Cost2, CostBest = ABC_INFINITY, Cost2Best = ABC_INFINITY;
    int WeightCur, WeightBest = -ABC_INFINITY, iGrp = -1, iGrpBest = -1;
    int k, c, iVar, Counter;
    // find partition that reduces partial product as much as possible
    for ( iVar = 0; iVar < p->nRows - p->nFfs; iVar++ )
    { 
        if ( p->pRowSums[iVar] < 2 )
            continue;
        // look at present variables that can be quantified
        if ( !(p->pProdVars[iVar] == 1 && p->pProdNums[iVar] == 1) )
            continue;
        // check that it appears in one partition only
        Counter = 0;
        for ( c = iGrpStart; c < p->nCols-1; c++ )
            if ( p->pMatrix[c][iVar] == 1 )
            {
                iGrp = c;
                Counter++;
            }
        assert( Counter == 1 );
        if ( Counter != 1 )
            Abc_Print( -1, "Llb_MtrFindBestColumn() Internal error!\n" );
        // find weight of this column
        WeightCur = 0;
        for ( k = 0; k < p->nRows; k++ )
        {
            // increase weight if variable k will be quantified from partial product
            if ( p->pProdVars[k] == 1 && p->pMatrix[iGrp][k] == 1 && p->pProdNums[k] == 1 ) 
                WeightCur += 2;
            // decrease weight if variable k will be added to partial product
            if ( p->pProdVars[k] == 0 && p->pMatrix[iGrp][k] == 1 )
                WeightCur--;
        }
        if ( WeightCur > 0 && WeightBest < WeightCur )
        {
            WeightBest = WeightCur;
            iGrpBest   = iGrp;
        }
    }
    if ( iGrpBest >= 0 )
        return iGrpBest;
    // could not find the group with any vars to quantify
    // select the group that contains as few extra variables as possible
    // if there is a tie, select variables that appear in less groups than others
    for ( iGrp = iGrpStart; iGrp < p->nCols-1; iGrp++ )
    {
        Cost = Cost2 = 0;
        for ( k = 0; k < p->nRows; k++ )
            if ( p->pProdVars[k] == 0 && p->pMatrix[iGrp][k] == 1 )
            {
                Cost++;
                Cost2 += p->pProdNums[k];
            }
        if ( CostBest >  Cost || 
            (CostBest == Cost && Cost2 > Cost2Best) )
        {
            CostBest  = Cost;
            Cost2Best = Cost2;
            iGrpBest  = iGrp;
        }
    }
    return iGrpBest;
}

/**Function*************************************************************

  Synopsis    [Returns the number of variables that will be saved.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Llb_MtrUseSelectedColumn( Llb_Mtr_t * p, int iCol )
{
    int iVar;
    assert( iCol >= 1 && iCol < p->nCols - 1 );
    for ( iVar = 0; iVar < p->nRows; iVar++ )
    {
        if ( p->pMatrix[iCol][iVar] == 0 )
            continue;
        if ( p->pProdVars[iVar] == 1 && p->pProdNums[iVar] == 1 )
        {
            p->pProdVars[iVar] = 0;
            p->pProdNums[iVar] = 0;
            continue;
        }
        if ( p->pProdVars[iVar] == 0 )
        {
            p->pProdVars[iVar] = 1;
            p->pProdNums[iVar] = p->pRowSums[iVar];
        }
        p->pProdNums[iVar]--;
        assert( p->pProdNums[iVar] >= 0 );
        if ( p->pProdNums[iVar] < 0 )
            Abc_Print( -1, "Llb_MtrUseSelectedColumn() Internal error!\n" );
    }
}

/**Function*************************************************************

  Synopsis    [Verify columns.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Llb_MtrVerifyColumns( Llb_Mtr_t * p, int iGrpStart )
{
    int iVar, iGrp, Counter;
    for ( iVar = 0; iVar < p->nRows; iVar++ )
    {
        if ( p->pProdVars[iVar] == 0 )
            continue;
        Counter = 0;
        for ( iGrp = iGrpStart; iGrp < p->nCols; iGrp++ )
            if ( p->pMatrix[iGrp][iVar] == 1 )
                Counter++;
        assert( Counter == p->pProdNums[iVar] );
        if ( Counter != p->pProdNums[iVar] )
            Abc_Print( -1, "Llb_MtrVerifyColumns(): Internal error.\n" );
    }
}

/**Function*************************************************************

  Synopsis    [Matrix reduce.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Llb_MtrSchedule( Llb_Mtr_t * p )
{
    int iGrp, iGrpBest, i;
    // start partial product
    for ( i = 0; i < p->nRows; i++ )
    {
        if ( i >= p->nPis && i < p->nPis + p->nFfs )
        {
            p->pProdVars[i] = 1;
            p->pProdNums[i] = p->pRowSums[i] - 1;
        }
        else 
        {
            p->pProdVars[i] = 0;
            p->pProdNums[i] = p->pRowSums[i];
        }
    }
    // order the partitions
    Llb_MtrVerifyMatrix( p );
    for ( iGrp = 1; iGrp < p->nCols-1; iGrp++ )
    {
        Llb_MtrVerifyColumns( p, iGrp );
        iGrpBest = Llb_MtrFindBestColumn( p, iGrp );
        Llb_MtrUseSelectedColumn( p, iGrpBest );
        Llb_MtrSwapColumns( p, iGrp, iGrpBest );
    }
    Llb_MtrVerifyMatrix( p );
}

////////////////////////////////////////////////////////////////////////
///                       END OF FILE                                ///
////////////////////////////////////////////////////////////////////////


ABC_NAMESPACE_IMPL_END