sc_signal_resolved.cc revision 13201:200a488db61f 
1/*
2 * Copyright 2018 Google, Inc.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met: redistributions of source code must retain the above copyright
7 * notice, this list of conditions and the following disclaimer;
8 * redistributions in binary form must reproduce the above copyright
9 * notice, this list of conditions and the following disclaimer in the
10 * documentation and/or other materials provided with the distribution;
11 * neither the name of the copyright holders nor the names of its
12 * contributors may be used to endorse or promote products derived from
13 * this software without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
19 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
21 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 * Authors: Gabe Black
28 */
29
30#include "base/logging.hh"
31#include "systemc/core/process.hh"
32#include "systemc/core/scheduler.hh"
33#include "systemc/ext/channel/sc_signal_resolved.hh"
34#include "systemc/ext/core/sc_module.hh" // for sc_gen_unique_name
35
36namespace sc_core
37{
38
39sc_signal_resolved::sc_signal_resolved() : sc_interface(),
40        sc_signal<sc_dt::sc_logic, SC_MANY_WRITERS>(
41                sc_gen_unique_name("signal_resolved"))
42{}
43
44sc_signal_resolved::sc_signal_resolved(const char *name) :
45        sc_interface(), sc_signal<sc_dt::sc_logic, SC_MANY_WRITERS>(name)
46{}
47
48sc_signal_resolved::~sc_signal_resolved() {}
49void sc_signal_resolved::register_port(sc_port_base &, const char *) {}
50
51void
52sc_signal_resolved::write(const sc_dt::sc_logic &l)
53{
54    ::sc_gem5::Process *p = ::sc_gem5::scheduler.current();
55
56    auto it = inputs.find(p);
57    if (it == inputs.end()) {
58        inputs.emplace(p, l);
59        request_update();
60    } else if (it->second != l) {
61        it->second = l;
62        request_update();
63    }
64}
65
66sc_signal_resolved &
67sc_signal_resolved::operator = (const sc_dt::sc_logic &l)
68{
69    write(l);
70    return *this;
71}
72
73sc_signal_resolved &
74sc_signal_resolved::operator = (const sc_signal_resolved &r)
75{
76    write(r.read());
77    return *this;
78}
79
80void
81sc_signal_resolved::update()
82{
83    using sc_dt::Log_0;
84    using sc_dt::Log_1;
85    using sc_dt::Log_Z;
86    using sc_dt::Log_X;
87    static sc_dt::sc_logic_value_t merge_table[4][4] = {
88        { Log_0, Log_X, Log_0, Log_X },
89        { Log_X, Log_1, Log_1, Log_X },
90        { Log_0, Log_1, Log_Z, Log_X },
91        { Log_X, Log_X, Log_X, Log_X }
92    };
93
94    // Resolve the inputs, and give the result to the underlying signal class.
95    m_new_val = Log_Z;
96    for (auto &input: inputs)
97        m_new_val = merge_table[m_new_val.value()][input.second.value()];
98
99    // Ask the signal to update it's value.
100    sc_signal<sc_dt::sc_logic, SC_MANY_WRITERS>::update();
101}
102
103} // namespace sc_core
104