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
|
/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2021 The SymbiFlow Authors.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#ifndef EXCLUSIVE_STATE_GROUPS_H
#define EXCLUSIVE_STATE_GROUPS_H
#include <array>
#include <bitset>
#include <cstdint>
#include <limits>
#include <vector>
#include "archdefs.h"
#include "bits.h"
#include "idstring.h"
#include "nextpnr_assertions.h"
#include "nextpnr_namespaces.h"
NEXTPNR_NAMESPACE_BEGIN
// Implementation for exclusive state groups, used to implement generic
// constraint system.
template <size_t StateCount, typename StateType = int8_t, typename CountType = uint8_t> struct ExclusiveStateGroup
{
ExclusiveStateGroup() : state(kNoSelected) { count.fill(0); }
struct Definition
{
IdString prefix;
IdString default_state;
std::vector<IdString> states;
};
static_assert(StateCount < std::numeric_limits<StateType>::max(), "StateType cannot store max StateType");
static_assert(std::numeric_limits<StateType>::is_signed, "StateType must be signed");
std::bitset<StateCount> selected_states;
StateType state;
std::array<CountType, StateCount> count;
static constexpr StateType kNoSelected = -1;
static constexpr StateType kOverConstrained = -2;
std::pair<bool, IdString> current_state(const Definition &definition) const
{
if (state <= 0) {
return std::make_pair(state == kNoSelected, definition.default_state);
} else {
NPNR_ASSERT(state <= definition.states.size());
return std::make_pair(true, definition.states[state]);
}
}
bool check_implies(int32_t next_state) const
{
// Implies can be satified if either that state is
// selected, or no state is currently selected.
return state == next_state || state == kNoSelected;
}
bool add_implies(int32_t next_state)
{
NPNR_ASSERT(next_state >= 0 && (size_t)next_state < StateCount);
// Increment and mark the state as selected.
count[next_state] += 1;
selected_states[next_state] = true;
if (state == next_state) {
// State was already selected, state group is still satified.
return true;
} else if (selected_states.count() == 1) {
// State was not select selected, state is now selected.
// State group is satified.
state = next_state;
return true;
} else {
// State group is now overconstrained.
state = kOverConstrained;
return false;
}
};
void remove_implies(int32_t next_state)
{
NPNR_ASSERT(next_state >= 0 && (size_t)next_state < StateCount);
NPNR_ASSERT(selected_states[next_state]);
count[next_state] -= 1;
NPNR_ASSERT(count[next_state] >= 0);
// Check if next_state is now unselected.
if (count[next_state] == 0) {
// next_state is not longer selected
selected_states[next_state] = false;
// Check whether the state group is now unselected or satified.
auto value = selected_states.to_ulong();
auto number_selected = nextpnr::Bits::popcount(value);
if (number_selected == 1) {
// Group is no longer overconstrained.
state = nextpnr::Bits::ctz(value);
NPNR_ASSERT(selected_states[state]);
} else if (number_selected == 0) {
// Group is unselected.
state = kNoSelected;
} else {
state = kOverConstrained;
}
}
}
template <typename StateRange> bool requires(const StateRange &state_range) const
{
if (state < 0) {
return false;
}
for (const auto required_state : state_range) {
if (state == required_state) {
return true;
}
}
return false;
}
void print_debug(const Context *ctx, IdString object, const Definition &definition) const;
void explain_implies(const Context *ctx, IdString object, IdString cell, const Definition &definition, BelId bel,
int32_t next_state) const;
template <typename StateRange>
void explain_requires(const Context *ctx, IdString object, IdString cell, const Definition &definition, BelId bel,
const StateRange state_range) const;
};
NEXTPNR_NAMESPACE_END
#endif
|
