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OpenFPGA/vpr7_x2p/vpr/SRC/device/mux_graph.cpp

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/**************************************************
* This file includes member functions for the
* data structures in mux_graph.h
*************************************************/
#include <cmath>
#include <algorithm>
#include "util.h"
#include "vtr_assert.h"
#include "mux_utils.h"
#include "mux_graph.h"
/**************************************************
* Member functions for the class MuxGraph
*************************************************/
/**************************************************
* Constructor
*************************************************/
/* Create an object based on a Circuit Model which is MUX */
MuxGraph::MuxGraph(const CircuitLibrary& circuit_lib,
const CircuitModelId& circuit_model,
const size_t& mux_size) {
/* Build the graph for a given multiplexer model */
build_mux_graph(circuit_lib, circuit_model, mux_size);
}
/**************************************************
* Public Accessors : Aggregates
*************************************************/
//Accessors
MuxGraph::node_range MuxGraph::nodes() const {
return vtr::make_range(node_ids_.begin(), node_ids_.end());
}
MuxGraph::edge_range MuxGraph::edges() const {
return vtr::make_range(edge_ids_.begin(), edge_ids_.end());
}
MuxGraph::mem_range MuxGraph::memories() const {
return vtr::make_range(mem_ids_.begin(), mem_ids_.end());
}
/**************************************************
* Public Accessors: Data query
*************************************************/
/* Find the number of inputs in the MUX graph */
size_t MuxGraph::num_inputs() const {
/* need to check if the graph is valid or not */
VTR_ASSERT_SAFE(valid_mux_graph());
/* Sum up the number of INPUT nodes in each level */
size_t num_inputs = 0;
for (auto node_per_level : node_lookup_) {
num_inputs += node_per_level[MUX_INPUT_NODE].size();
}
return num_inputs;
}
/* Find the number of levels in the MUX graph */
size_t MuxGraph::num_levels() const {
/* need to check if the graph is valid or not */
VTR_ASSERT_SAFE(valid_mux_graph());
/* The num_levels by definition excludes the level for outputs, so a deduection is applied */
return node_lookup_.size() - 1;
}
/* Find the number of configuration memories in the MUX graph */
size_t MuxGraph::num_memory_bits() const {
/* need to check if the graph is valid or not */
VTR_ASSERT_SAFE(valid_mux_graph());
return mem_ids_.size();
}
/* Find the sizes of each branch of a MUX */
std::vector<size_t> MuxGraph::branch_sizes() const {
std::vector<size_t> branch;
/* Visit each internal nodes/output nodes and find the the number of incoming edges */
for (auto node : node_ids_ ) {
/* Bypass input nodes */
if ( (MUX_OUTPUT_NODE != node_types_[node])
&& (MUX_INTERNAL_NODE != node_types_[node]) ) {
continue;
}
size_t branch_size = node_in_edges_[node].size();
/* make sure the branch size is valid */
VTR_ASSERT_SAFE(valid_mux_implementation_num_inputs(branch_size));
/* Nodes with the same number of incoming edges, indicate the same size of branch circuit */
std::vector<size_t>::iterator it;
it = std::find(branch.begin(), branch.end(), branch_size);
/* if already exists a branch with the same size, skip updating the vector */
if (it == branch.end()) {
continue;
}
branch.push_back(branch_size);
}
/* Sort the branch by size */
std::sort(branch.begin(), branch.end());
return branch;
}
/* Get the node id of a given input */
MuxNodeId MuxGraph::node_id(const MuxInputId& input_id) const {
/* Use the node_lookup to accelerate the search */
for (const auto& lvl : node_lookup_) {
for (const auto& cand_node : lvl[MUX_INPUT_NODE]) {
if (input_id == node_input_ids_[cand_node]) {
return cand_node;
}
}
}
return MuxNodeId::INVALID();
}
/* Decode memory bits based on an input id */
std::vector<size_t> MuxGraph::decode_memory_bits(const MuxInputId& input_id) const {
/* initialize the memory bits: TODO: support default value */
std::vector<size_t> mem_bits(mem_ids_.size(), 0);
/* valid the input */
VTR_ASSERT_SAFE(valid_input_id(input_id));
/* Route the input to the output and update mem */
MuxNodeId next_node = node_id(input_id);
while ( 0 < node_out_edges_[next_node].size() ) {
VTR_ASSERT_SAFE (1 == node_out_edges_[next_node].size());
MuxEdgeId edge = node_out_edges_[next_node][0];
/* Configure the mem bits:
* if inv_mem is enabled, it means 0 to enable this edge
* otherwise, it is 1 to enable this edge
*/
MuxMemId mem = edge_mem_ids_[edge];
VTR_ASSERT_SAFE (valid_mem_id(mem));
if (true == edge_inv_mem_[edge]) {
mem_bits[size_t(mem)] = 0;
} else {
mem_bits[size_t(mem)] = 1;
}
/* each edge must have 1 fan-out */
VTR_ASSERT_SAFE (1 == edge_sink_nodes_[edge].size());
/* Visit the next node */
next_node = edge_sink_nodes_[edge][0];
}
VTR_ASSERT_SAFE(MUX_OUTPUT_NODE == node_types_[next_node]);
return mem_bits;
}
/**************************************************
* Private mutators: basic operations
*************************************************/
/* Add a unconfigured node to the MuxGraph */
MuxNodeId MuxGraph::add_node(const enum e_mux_graph_node_type& node_type) {
MuxNodeId node = MuxNodeId(node_ids_.size());
/* Push to the node list */
node_ids_.push_back(node);
/* Resize the other node-related vectors */
node_types_.push_back(node_type);
node_input_ids_.push_back(MuxInputId::INVALID());
node_levels_.push_back(-1);
node_in_edges_.emplace_back();
node_out_edges_.emplace_back();
return node;
}
/* Add a edge connecting two nodes */
MuxEdgeId MuxGraph::add_edge(const MuxNodeId& from_node, const MuxNodeId& to_node) {
MuxEdgeId edge = MuxEdgeId(edge_ids_.size());
/* Push to the node list */
edge_ids_.push_back(edge);
/* Resize the other node-related vectors */
edge_types_.push_back(NUM_CIRCUIT_MODEL_PASS_GATE_TYPES);
edge_mem_ids_.push_back(MuxMemId::INVALID());
edge_inv_mem_.push_back(false);
/* update the edge-node connections */
VTR_ASSERT(valid_node_id(from_node));
edge_src_nodes_.emplace_back();
edge_src_nodes_[edge].push_back(from_node);
node_out_edges_[from_node].push_back(edge);
VTR_ASSERT(valid_node_id(to_node));
edge_sink_nodes_.emplace_back();
edge_sink_nodes_[edge].push_back(to_node);
node_in_edges_[to_node].push_back(edge);
return edge;
}
/* Add a memory bit to the MuxGraph */
MuxMemId MuxGraph::add_mem() {
MuxMemId mem = MuxMemId(mem_ids_.size());
/* Push to the node list */
mem_ids_.push_back(mem);
/* Resize the other node-related vectors */
return mem;
}
/* Link an edge to a memory bit */
void MuxGraph::set_edge_mem_id(const MuxEdgeId& edge, const MuxMemId& mem) {
/* Make sure we have valid edge and mem */
VTR_ASSERT( valid_edge_id(edge) && valid_mem_id(mem) );
edge_mem_ids_[edge] = mem;
}
/**************************************************
* Private mutators: graph builders
*************************************************/
/* Build a graph for a multi-level multiplexer implementation
* support both generic multi-level and tree-like multiplexers
*
* a N:1 multi-level MUX
* ----------------------
*
* input_node --->+
* |
* input_node --->|
* |--->+
* ... | |
* | |
* input_node --->+ |---> ...
* |
* ... --->+ --->+
* |
* ... ... |---> output_node
* |
* ... --->+ --->+
* |
* input_node --->+ |---> ...
* | |
* input_node --->| |
* |--->+
* ... |
* |
* input_node --->+
*
* tree-like multiplexer graph will look like:
* --------------------------------------------
*
* input_node --->+
* |--->+
* input_node --->+ |---> ...
* |
* --->+ --->+
* ... ... ... |----> output_node
* ... --->+ --->+
* |---> ...
* input_node --->+ |
* |--->+
* input_node --->+
*
*/
void MuxGraph::build_multilevel_mux_graph(const size_t& mux_size,
const size_t& num_levels, const size_t& num_inputs_per_branch,
const enum e_spice_model_pass_gate_logic_type& pgl_type) {
/* Make sure mux_size for each branch is valid */
VTR_ASSERT(valid_mux_implementation_num_inputs(num_inputs_per_branch));
/* In regular cases, there is 1 mem bit for each input of a branch */
size_t num_mems_per_level = num_inputs_per_branch;
/* For 2-input branch, only 1 mem bit is needed for each level! */
if (2 == num_inputs_per_branch) {
num_mems_per_level = 1;
}
/* Number of memory bits is definite, add them */
for (size_t i = 0; i < num_mems_per_level * num_levels; ++i) {
add_mem();
}
/* Create a fast node lookup locally.
* Only used for building the graph
* it sorts the nodes by levels and ids at each level
*/
std::vector<std::vector<MuxNodeId>> node_lookup; /* [num_levels][num_nodes_per_level] */
node_lookup.resize(num_levels + 1);
/* Number of outputs is definite, add and configure */
MuxNodeId output_node = add_node(MUX_OUTPUT_NODE);
node_levels_[output_node] = num_levels;
/* Update node lookup */
node_lookup[num_levels].push_back(output_node);
/* keep a list of node ids which can be candidates for input nodes */
std::vector<MuxNodeId> input_node_ids;
/* Add internal nodes level by level,
* we start from the last level, following a strategy like tree growing
*/
for (size_t lvl = num_levels - 1; ; --lvl) {
/* Expand from the existing nodes
* Last level should expand from output_node
* Other levels will expand from internal nodes!
*/
for (MuxNodeId seed_node : node_lookup[lvl + 1]) {
/* Add a new node and connect to seed_node, until we reach the num_inputs_per_branch */
for (size_t i = 0; i < num_inputs_per_branch; ++i) {
/* We deposite a type of INTERNAL_NODE,
* later it will be configured to INPUT if it is in the input list
*/
MuxNodeId expand_node = add_node(MUX_INTERNAL_NODE);
/* Node level is deterministic */
node_levels_[expand_node] = lvl;
/* Create an edge and connect the two nodes */
MuxEdgeId edge = add_edge(expand_node, seed_node);
/* Configure the edge */
edge_types_[edge] = pgl_type;
/* Memory id depends on the level and offset in the current branch
* if number of inputs per branch is 2, it indicates a tree-like multiplexer,
* every two edges will share one memory bit
* otherwise, each edge corresponds to a memory bit
*/
if ( 2 == num_inputs_per_branch) {
MuxMemId mem_id = MuxMemId(lvl);
set_edge_mem_id(edge, mem_id);
/* If this is a second edge in the branch, we will assign it to an inverted edge */
if (0 != i % num_inputs_per_branch) {
edge_inv_mem_[edge] = true;
}
} else {
MuxMemId mem_id = MuxMemId( lvl * num_inputs_per_branch + i );
set_edge_mem_id(edge, mem_id);
}
/* Update node lookup */
node_lookup[lvl].push_back(expand_node);
/* Push the node to input list, and then remove the seed_node from the list */
input_node_ids.push_back(expand_node);
/* Remove the node if the seed node is the list */
std::vector<MuxNodeId>::iterator it = find(input_node_ids.begin(), input_node_ids.end(), seed_node);
if (it != input_node_ids.end()) {
input_node_ids.erase(it);
}
/* Check the number of input nodes, if already meet the demand, we can finish here */
if (mux_size != input_node_ids.size()) {
continue; /* We need more inputs, keep looping */
}
/* The graph is done, we configure the input nodes and then we can return */
/* We must be in level 0 !*/
VTR_ASSERT( 0 == lvl ) ;
for (MuxNodeId input_node : input_node_ids) {
node_types_[input_node] = MUX_INPUT_NODE;
}
/* Sort the nodes by the levels and offset */
size_t input_cnt = 0;
for (auto lvl_nodes : node_lookup) {
for (MuxNodeId cand_node : lvl_nodes) {
if (MUX_INPUT_NODE != node_types_[cand_node]) {
continue;
}
/* Update the input node ids */
node_input_ids_[cand_node] = MuxInputId(input_cnt);
/* Update the counter */
input_cnt++;
}
}
/* Make sure we visited all the inputs in the cache */
VTR_ASSERT(input_cnt == input_node_ids.size());
/* Finish building the graph for a multi-level multiplexer */
return;
}
}
}
/* Finish building the graph for a multi-level multiplexer */
}
/* Build the graph for a given one-level multiplexer implementation
* a N:1 one-level MUX
*
* input_node --->+
* |
* input_node --->|
* |--> output_node
* ... |
* |
* input_node --->+
*/
void MuxGraph::build_onelevel_mux_graph(const size_t& mux_size,
const enum e_spice_model_pass_gate_logic_type& pgl_type) {
/* Make sure mux_size is valid */
VTR_ASSERT(valid_mux_implementation_num_inputs(mux_size));
/* We definitely know how many nodes we need,
* N inputs, 1 output and 0 internal nodes
*/
MuxNodeId output_node = add_node(MUX_OUTPUT_NODE);
node_levels_[output_node] = 1;
for (size_t i = 0; i < mux_size; ++i) {
MuxNodeId input_node = add_node(MUX_INPUT_NODE);
/* All the node belong to level 0 (we have only 1 level) */
node_input_ids_[input_node] = MuxInputId(i);
node_levels_[input_node] = 0;
/* We definitely know how many edges we need,
* the same as mux_size, add a edge connecting two nodes
*/
MuxEdgeId edge = add_edge(input_node, output_node);
/* Configure the edge */
edge_types_[edge] = pgl_type;
/* Create a memory bit*/
MuxMemId mem = add_mem();
/* Link the edge to a memory bit */
set_edge_mem_id(edge, mem);
}
/* Finish building the graph for a one-level multiplexer */
}
/* Build the graph for a given multiplexer model */
void MuxGraph::build_mux_graph(const CircuitLibrary& circuit_lib,
const CircuitModelId& circuit_model,
const size_t& mux_size) {
/* Make sure this model is a MUX */
VTR_ASSERT((SPICE_MODEL_MUX == circuit_lib.circuit_model_type(circuit_model))
|| (SPICE_MODEL_LUT == circuit_lib.circuit_model_type(circuit_model)) );
/* Make sure mux_size is valid */
VTR_ASSERT(valid_mux_implementation_num_inputs(mux_size));
size_t impl_mux_size = find_mux_implementation_num_inputs(circuit_lib, circuit_model, mux_size);
/* Depends on the mux size, the implemented multiplexer structure may change! */
enum e_spice_model_structure impl_structure = find_mux_implementation_structure(circuit_lib, circuit_model, impl_mux_size);
/* Branch on multiplexer structures, leading to different building strategies */
switch (impl_structure) {
case SPICE_MODEL_STRUCTURE_TREE: {
/* Find the number of levels */
size_t num_levels = find_treelike_mux_num_levels(impl_mux_size);
/* Find the number of inputs per branch, this is not final */
size_t num_inputs_per_branch = 2;
/* Build a multilevel mux graph */
build_multilevel_mux_graph(impl_mux_size, num_levels, num_inputs_per_branch, circuit_lib.pass_gate_logic_type(circuit_model));
break;
}
case SPICE_MODEL_STRUCTURE_ONELEVEL: {
build_onelevel_mux_graph(impl_mux_size, circuit_lib.pass_gate_logic_type(circuit_model));
break;
}
case SPICE_MODEL_STRUCTURE_MULTILEVEL: {
/* Find the number of inputs per branch, this is not final */
size_t num_inputs_per_branch = find_multilevel_mux_branch_num_inputs(impl_mux_size, circuit_lib.mux_num_levels(circuit_model));
/* Build a multilevel mux graph */
build_multilevel_mux_graph(impl_mux_size, circuit_lib.mux_num_levels(circuit_model),
num_inputs_per_branch,
circuit_lib.pass_gate_logic_type(circuit_model));
break;
}
default:
vpr_printf(TIO_MESSAGE_ERROR,
"(File:%s, [LINE%d]) Invalid multiplexer structure for circuit model (name=%s)!\n",
__FILE__, __LINE__, circuit_lib.circuit_model_name(circuit_model));
exit(1);
}
/* Since the graph is finalized, it is time to build the fast look-up */
build_node_lookup();
}
/* Build fast node lookup */
void MuxGraph::build_node_lookup() {
/* Invalidate the node lookup if necessary */
invalidate_node_lookup();
/* Find the maximum number of levels */
size_t num_levels = 0;
for (auto node : nodes()) {
num_levels = std::max((int)node_levels_[node], (int)num_levels);
}
/* Resize node_lookup */
node_lookup_.resize(num_levels + 1);
for (size_t lvl = 0; lvl < node_lookup_.size(); ++lvl) {
/* Resize by number of node types */
node_lookup_[lvl].resize(NUM_MUX_NODE_TYPES);
}
/* Fill the node lookup */
for (auto node : nodes()) {
node_lookup_[node_levels_[node]][size_t(node_types_[node])].push_back(node);
}
}
/* Invalidate (empty) the node fast lookup*/
void MuxGraph::invalidate_node_lookup() {
node_lookup_.clear();
}
/**************************************************
* Private validators
*************************************************/
/* valid ids */
bool MuxGraph::valid_node_id(const MuxNodeId& node) const {
return size_t(node) < node_ids_.size() && node_ids_[node] == node;
}
bool MuxGraph::valid_edge_id(const MuxEdgeId& edge) const {
return size_t(edge) < edge_ids_.size() && edge_ids_[edge] == edge;
}
bool MuxGraph::valid_mem_id(const MuxMemId& mem) const {
return size_t(mem) < mem_ids_.size() && mem_ids_[mem] == mem;
}
/* validate an input id (from which data path signal will be progagated to the output */
bool MuxGraph::valid_input_id(const MuxInputId& input_id) const {
for (const auto& lvl : node_lookup_) {
for (const auto& node : lvl[MUX_INPUT_NODE]) {
if (size_t(input_id) > size_t(node_input_ids_[node])) {
return false;
}
}
}
return true;
}
bool MuxGraph::valid_node_lookup() const {
return node_lookup_.empty();
}
/* validate a mux graph and see if it is valid */
bool MuxGraph::valid_mux_graph() const {
/* A valid MUX graph should be
* 1. every node has 1 fan-out except output node
* 2. every input can be routed to the output node
*/
for (const auto& node : nodes()) {
/* output node has 0 fan-out*/
if (MUX_OUTPUT_NODE == node_types_[node]) {
continue;
}
/* other nodes should have 1 fan-out */
if (1 != node_out_edges_[node].size()) {
return false;
}
}
/* Try to route to output */
for (const auto& node : nodes()) {
if (MUX_INPUT_NODE == node_types_[node]) {
MuxNodeId next_node = node;
while ( 0 < node_out_edges_[next_node].size() ) {
MuxEdgeId edge = node_out_edges_[next_node][0];
/* each edge must have 1 fan-out */
if (1 != edge_sink_nodes_[edge].size()) {
return false;
}
next_node = edge_sink_nodes_[edge][0];
}
if (MUX_OUTPUT_NODE != node_types_[next_node]) {
return false;
}
}
}
return true;
}
/**************************************************
* End of Member functions for the class MuxGraph
*************************************************/
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