scfx_pow10.cc revision 12854:c95c35407325 
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20/*****************************************************************************
21
22  scfx_pow10.cpp -
23
24  Original Author: Robert Graulich, Synopsys, Inc.
25                   Martin Janssen,  Synopsys, Inc.
26
27 *****************************************************************************/
28
29/*****************************************************************************
30
31  MODIFICATION LOG - modifiers, enter your name, affiliation, date and
32  changes you are making here.
33
34      Name, Affiliation, Date:
35  Description of Modification:
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37 *****************************************************************************/
38
39
40// $Log: scfx_pow10.cpp,v $
41// Revision 1.1.1.1  2006/12/15 20:20:04  acg
42// SystemC 2.3
43//
44// Revision 1.3  2006/01/13 18:53:58  acg
45// Andy Goodrich: added $Log command so that CVS comments are reproduced in
46// the source.
47//
48
49#include "systemc/ext/dt/fx/scfx_pow10.hh"
50
51namespace sc_dt
52{
53
54// ----------------------------------------------------------------------------
55//  CLASS : scfx_pow10
56//
57//  Class to compute (and cache) powers of 10 in arbitrary precision.
58// ----------------------------------------------------------------------------
59
60scfx_pow10::scfx_pow10()
61{
62    m_pos[0] = scfx_rep(10.0);
63    m_neg[0] = scfx_rep(0.1);
64
65    for (int i = 1; i < SCFX_POW10_TABLE_SIZE; i++) {
66        m_pos[i].set_nan();
67        m_neg[i].set_nan();
68    }
69}
70
71scfx_pow10::~scfx_pow10() {}
72
73const scfx_rep
74scfx_pow10::operator() (int i)
75{
76    if (i == 0) {
77        return scfx_rep(1.0);
78    }
79
80    if (i > 0) {
81        int bit = scfx_find_msb(i);
82        scfx_rep result = *pos(bit);
83        if (bit) {
84            while (--bit >= 0) {
85                if ((1 << bit) & i) {
86                    scfx_rep *tmp = mult_scfx_rep(result, *pos(bit));
87                    result = *tmp;
88                    delete tmp;
89                }
90            }
91        }
92        return result;
93    } else {
94        i = -i;
95        int bit = scfx_find_msb(i);
96        scfx_rep result = *neg(bit);
97        if (bit) {
98            while (--bit >= 0) {
99                if ((1 << bit) & i) {
100                    scfx_rep *tmp = mult_scfx_rep(result, *neg(bit));
101                    result = *tmp;
102                    delete tmp;
103                }
104            }
105        }
106        return result;
107    }
108}
109
110
111scfx_rep *
112scfx_pow10::pos(int i)
113{
114    if (!m_pos[i].is_normal()) {
115        multiply(m_pos[i], *pos(i - 1), *pos(i - 1));
116    }
117    return &m_pos[i];
118}
119
120scfx_rep *
121scfx_pow10::neg(int i)
122{
123    if (!m_neg[i].is_normal()) {
124        multiply(m_neg[i], *neg(i - 1), *neg(i - 1));
125    }
126    return &m_neg[i];
127}
128
129} // namespace sc_dt
130