464 lines
14 KiB
C++
464 lines
14 KiB
C++
/*
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* Copyright (c) 2008-2010 Stephen Williams (steve@icarus.com)
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*
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* This source code is free software; you can redistribute it
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* and/or modify it in source code form under the terms of the GNU
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* General Public License as published by the Free Software
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* Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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# include "vvp_island.h"
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# include "compile.h"
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# include "symbols.h"
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# include "schedule.h"
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# include <list>
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using namespace std;
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class vvp_island_tran : public vvp_island {
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public:
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void run_island();
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};
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struct vvp_island_branch_tran : public vvp_island_branch {
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// Behavior. (This stuff should be moved to a derived
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// class. The members here are specific to the tran island
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// class.)
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vvp_island_branch_tran(vvp_net_t*en__, bool active_high__,
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unsigned width__, unsigned part__,
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unsigned offset__);
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bool run_test_enabled();
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void run_resolution();
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void clear_resolution_flags() { flags_ &= ~0x0f; }
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void mark_done(unsigned ab) { flags_ |= 1 << ab; }
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bool test_done(unsigned ab) const { return flags_ & (1<<ab); }
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void clear_visited(unsigned ab) { flags_ &= ~(4 << ab); }
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void mark_visited(unsigned ab) { flags_ |= 4 << ab; }
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bool test_visited(unsigned ab) const { return flags_ & (4<<ab); }
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// Use the peek only for diagnostic purposes.
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int peek_flags() const { return flags_; }
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vvp_net_t*en;
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unsigned width, part, offset;
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bool active_high;
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bool enabled_flag;
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private:
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int flags_;
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};
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vvp_island_branch_tran::vvp_island_branch_tran(vvp_net_t*en__,
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bool active_high__,
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unsigned width__,
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unsigned part__,
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unsigned offset__)
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: en(en__), width(width__), part(part__), offset(offset__),
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active_high(active_high__)
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{
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flags_ = 0;
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enabled_flag = en__ ? false : true;
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}
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static inline vvp_island_branch_tran* BRANCH_TRAN(vvp_island_branch*tmp)
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{
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vvp_island_branch_tran*res = dynamic_cast<vvp_island_branch_tran*>(tmp);
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assert(res);
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return res;
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}
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/*
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* The run_island() method is called by the scheduler to run the
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* entire island. We run the island by calling run_resolution() for
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* all the branches in the island.
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*/
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void vvp_island_tran::run_island()
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{
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// Test to see if any of the branches are enabled. This loop
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// tests the enabled inputs for all the branches and caches
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// the results in the enabled_flag for each branch. The
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// run_test_enabled() method also clears all the processing
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// flags for the branches so that we are in a good start
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// state.
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bool runnable = false;
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for (vvp_island_branch*cur = branches_ ; cur ; cur = cur->next_branch) {
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vvp_island_branch_tran*tmp = dynamic_cast<vvp_island_branch_tran*>(cur);
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assert(tmp);
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runnable |= tmp->run_test_enabled();
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}
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// Now resolve all the branches in the island.
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for (vvp_island_branch*cur = branches_ ; cur ; cur = cur->next_branch) {
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vvp_island_branch_tran*tmp = dynamic_cast<vvp_island_branch_tran*>(cur);
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assert(tmp);
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tmp->run_resolution();
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}
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}
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bool vvp_island_branch_tran::run_test_enabled()
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{
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// Clear all the flags.
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clear_resolution_flags();
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vvp_island_port*ep = en? dynamic_cast<vvp_island_port*> (en->fun) : 0;
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// If there is no ep port (no "enabled" input) then this is a
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// tran branch. Assume it is always enabled.
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if (ep == 0) {
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enabled_flag = true;
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return true;
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}
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// Get the input that is driving this enable.
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// SPECIAL NOTE: Try to get the input value from the
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// *outvalue* of the port. If the enable is connected to a
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// .port (instead of a .import) then there may be feedback
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// going on, and we need to be looking at the resolved input,
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// not the event input. For example:
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//
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// tranif1 (pin, X, pin);
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//
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// In this case, when we test the value for "pin", we need to
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// look at the value that is resolved from this
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// island. Reading the outvalue will do the trick.
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//
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// If the outvalue is nil, then we know that this port is a
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// .import after all, so just read the invalue.
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enabled_flag = false;
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vvp_bit4_t enable_val;
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if (ep->outvalue.size() != 0)
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enable_val = ep->outvalue.value(0).value();
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else if (ep->invalue.size() == 0)
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enable_val = BIT4_Z;
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else
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enable_val = ep->invalue.value(0).value();
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if (active_high==true && enable_val != BIT4_1)
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return false;
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if (active_high==false && enable_val != BIT4_0)
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return false;
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enabled_flag = true;
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return true;
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}
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static void island_send_value(list<vvp_branch_ptr_t>&connections, const vvp_vector8_t&val)
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{
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for (list<vvp_branch_ptr_t>::iterator idx = connections.begin()
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; idx != connections.end() ; ++ idx ) {
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vvp_island_branch*tmp_ptr = idx->ptr();
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unsigned tmp_ab = idx->port();
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island_send_value(tmp_ab? tmp_ptr->b : tmp_ptr->a, val);
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}
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}
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static void mark_done_flags(list<vvp_branch_ptr_t>&connections)
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{
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for (list<vvp_branch_ptr_t>::iterator idx = connections.begin()
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; idx != connections.end() ; ++ idx ) {
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vvp_island_branch*tmp_ptr = idx->ptr();
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vvp_island_branch_tran*cur = dynamic_cast<vvp_island_branch_tran*>(tmp_ptr);
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unsigned tmp_ab = idx->port();
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cur->mark_done(tmp_ab);
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}
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}
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static void mark_visited_flags(list<vvp_branch_ptr_t>&connections)
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{
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for (list<vvp_branch_ptr_t>::iterator idx = connections.begin()
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; idx != connections.end() ; ++ idx ) {
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vvp_island_branch*tmp_ptr = idx->ptr();
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vvp_island_branch_tran*cur = dynamic_cast<vvp_island_branch_tran*>(tmp_ptr);
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assert(cur);
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unsigned tmp_ab = idx->port();
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cur->mark_visited(tmp_ab);
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}
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}
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static void clear_visited_flags(list<vvp_branch_ptr_t>&connections)
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{
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for (list<vvp_branch_ptr_t>::iterator idx = connections.begin()
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; idx != connections.end() ; ++ idx ) {
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vvp_island_branch_tran*tmp_ptr = BRANCH_TRAN(idx->ptr());
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unsigned tmp_ab = idx->port();
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tmp_ptr->clear_visited(tmp_ab);
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}
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}
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static vvp_vector8_t get_value_from_branch(vvp_branch_ptr_t cur);
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static void resolve_values_from_connections(vvp_vector8_t&val,
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list<vvp_branch_ptr_t>&connections)
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{
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for (list<vvp_branch_ptr_t>::iterator idx = connections.begin()
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; idx != connections.end() ; ++ idx ) {
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vvp_vector8_t tmp = get_value_from_branch(*idx);
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if (val.size() == 0)
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val = tmp;
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else if (tmp.size() != 0)
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val = resolve(val, tmp);
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}
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}
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static vvp_vector8_t get_value_from_branch(vvp_branch_ptr_t cur)
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{
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vvp_island_branch_tran*ptr = BRANCH_TRAN(cur.ptr());
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assert(ptr);
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unsigned ab = cur.port();
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unsigned ab_other = ab^1;
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// If the branch link is disabled, return nil.
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if (ptr->enabled_flag == false)
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return vvp_vector8_t();
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vvp_branch_ptr_t other (ptr, ab_other);
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// If the branch other side is already visited, return
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// nil. This prevents recursion loops.
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if (ptr->test_visited(ab_other))
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return vvp_vector8_t();
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// Other side net, and port value.
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vvp_net_t*net_other = ab? ptr->a : ptr->b;
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vvp_vector8_t val_other = island_get_value(net_other);
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// recurse
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list<vvp_branch_ptr_t> connections;
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island_collect_node(connections, other);
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mark_visited_flags(connections);
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resolve_values_from_connections(val_other, connections);
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// Remove/unwind visited flags
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clear_visited_flags(connections);
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if (val_other.size() == 0)
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return val_other;
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if (ptr->width) {
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if (ab == 0) {
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val_other = part_expand(val_other, ptr->width, ptr->offset);
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} else {
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val_other = val_other.subvalue(ptr->offset, ptr->part);
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}
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}
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return val_other;
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}
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/*
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* Try to recursively push a fully resolved value back through the
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* graph. This can save many span iterations through the graph by
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* marking as done that are obviously and easily done. But it is
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* better to be conservative here.
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*
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* The connections list is filled with connections that are already
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* marked done, and the val is the resolved value. We are going to try
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* to follow branches to see if we can push the value further and mark
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* the other side done as well.
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*/
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static void push_value_through_branches(const vvp_vector8_t&val,
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list<vvp_branch_ptr_t>&connections)
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{
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for (list<vvp_branch_ptr_t>::iterator idx = connections.begin()
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; idx != connections.end() ; ++ idx ) {
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vvp_island_branch_tran*tmp_ptr = BRANCH_TRAN(idx->ptr());
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unsigned tmp_ab = idx->port();
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unsigned other_ab = tmp_ab^1;
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// If other side already done, skip
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if (tmp_ptr->test_done(other_ab))
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continue;
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// If link is not enabled, skip.
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if (! tmp_ptr->enabled_flag)
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continue;
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vvp_net_t*other_net = other_ab? tmp_ptr->b : tmp_ptr->a;
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if (tmp_ptr->width == 0) {
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// There are no part selects, so we can safely
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// Mark this end as done.
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tmp_ptr->mark_done(other_ab);
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island_send_value(other_net, val);
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} else if (other_ab == 1) {
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// The other side is a strict subset (part select)
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// of this side, so we can mark this end as done.
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tmp_ptr->mark_done(other_ab);
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vvp_vector8_t tmp = val.subvalue(tmp_ptr->offset, tmp_ptr->part);
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island_send_value(other_net, tmp);
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} else {
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// Otherwise, the other side is not fully
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// specified (is a subset of the done side) so we
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// can't take this shortcut.
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}
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}
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}
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/*
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* This method resolves the value for a branch recursively. It uses
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* recursive descent to span the graph of branches, collecting values
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* that need to be resolved together.
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*/
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void vvp_island_branch_tran::run_resolution()
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{
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// Collect all the branch endpoints that are joined to my A
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// side.
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list<vvp_branch_ptr_t> connections;
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bool processed_a_side = false;
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vvp_vector8_t val;
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// The "flags" member is a bitmask that marks whether an
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// endpoint of a branch has been visited. If flags&1, then the
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// A side has been visited. If flags&2, then the B side has
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// been visited. The flags help us avoid recursion when doing
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// spanning trees.
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// If the A side has already been completed, then skip it.
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if (! test_done(0)) {
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processed_a_side = true;
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vvp_branch_ptr_t a_side(this, 0);
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island_collect_node(connections, a_side);
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// Mark my A side as done. Do this early to prevent recursing
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// back. All the connections that share this port are also
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// done. Make sure their flags are set appropriately.
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mark_done_flags(connections);
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// Start with my branch-point value.
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val = island_get_value(a);
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mark_visited_flags(connections); // Mark as visited.
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// Now scan the other sides of all the branches connected to
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// my A side. The get_value_from_branch() will recurse as
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// necessary to depth-first walk the graph.
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resolve_values_from_connections(val, connections);
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// A side is done.
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island_send_value(connections, val);
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// Clear the visited flags. This must be done so that other
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// branches can read this input value.
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clear_visited_flags(connections);
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// Try to push the calculated value out through the
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// branches. This is useful for A-side results because
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// there is a high probability that the other side of
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// all the connected branches is fully specified by this
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// result.
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push_value_through_branches(val, connections);
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}
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// If the B side got taken care of by above, then this branch
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// is done. Stop now.
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if (test_done(1))
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return;
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// Repeat the above for the B side.
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connections.clear();
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island_collect_node(connections, vvp_branch_ptr_t(this, 1));
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mark_done_flags(connections);
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if (enabled_flag && processed_a_side) {
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// If this is a connected branch, then we know from the
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// start that we have all the bits needed to complete
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// the B side. Even if the B side is a part select, the
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// simple part select must be correct because the
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// recursive resolve_values_from_connections above must
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// of cycled back to the B side of myself when resolving
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// the connections.
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if (width != 0)
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val = val.subvalue(offset, part);
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} else {
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// If this branch is not enabled, then the B-side must
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// be processed on its own.
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val = island_get_value(b);
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mark_visited_flags(connections);
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resolve_values_from_connections(val, connections);
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clear_visited_flags(connections);
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}
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island_send_value(connections, val);
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}
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void compile_island_tran(char*label)
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{
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vvp_island*use_island = new vvp_island_tran;
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compile_island_base(label, use_island);
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}
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void compile_island_tranif(int sense, char*island, char*pa, char*pb, char*pe)
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{
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vvp_island*use_island = compile_find_island(island);
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assert(use_island);
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free(island);
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vvp_net_t*en = NULL;
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if (pe) {
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en = use_island->find_port(pe);
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assert(en);
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free(pe);
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}
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vvp_island_branch_tran*br = new vvp_island_branch_tran(en,
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sense ? true :
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false,
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0, 0, 0);
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use_island->add_branch(br, pa, pb);
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free(pa);
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free(pb);
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}
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void compile_island_tranvp(char*island, char*pa, char*pb,
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unsigned wid, unsigned par, unsigned off)
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{
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vvp_island*use_island = compile_find_island(island);
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assert(use_island);
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free(island);
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vvp_island_branch_tran*br = new vvp_island_branch_tran(NULL, false,
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wid, par, off) ;
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use_island->add_branch(br, pa, pb);
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free(pa);
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free(pb);
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}
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