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 = Bits::popcount(value);
if (number_selected == 1) {
// Group is no longer overconstrained.
state = 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_range(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
|