Improved FSM one-hot encoding, added binary encoding
authorClifford Wolf <clifford@clifford.at>
Fri, 24 May 2013 12:39:19 +0000 (14:39 +0200)
committerClifford Wolf <clifford@clifford.at>
Fri, 24 May 2013 12:39:19 +0000 (14:39 +0200)
passes/fsm/fsm.cc
passes/fsm/fsm_map.cc
passes/fsm/fsm_recode.cc

index c0c42de9f9bf60fb8bc04c92d2a330c6e0f11ec4..b4d7bc46fadfe56f92c7d2323175c7ec315bb215 100644 (file)
@@ -56,6 +56,7 @@ struct FsmPass : public Pass {
                log("    -expand, -norecode, -export, -nomap\n");
                log("        enable or disable passes as indicated above\n");
                log("\n");
+               log("    -encoding tye\n");
                log("    -fm_set_fsm_file file\n");
                log("        passed through to fsm_recode pass\n");
                log("\n");
@@ -67,6 +68,7 @@ struct FsmPass : public Pass {
                bool flag_expand = false;
                bool flag_export = false;
                std::string fm_set_fsm_file_opt;
+               std::string encoding_opt;
 
                log_header("Executing FSM pass (extract and optimize FSM).\n");
                log_push();
@@ -78,6 +80,10 @@ struct FsmPass : public Pass {
                                fm_set_fsm_file_opt = " -fm_set_fsm_file " + args[++argidx];
                                continue;
                        }
+                       if (arg == "-encoding" && argidx+1 < args.size() && fm_set_fsm_file_opt.empty()) {
+                               encoding_opt = " -encoding " + args[++argidx];
+                               continue;
+                       }
                        if (arg == "-norecode") {
                                flag_norecode = true;
                                continue;
@@ -112,7 +118,7 @@ struct FsmPass : public Pass {
                }
 
                if (!flag_norecode)
-                       Pass::call(design, "fsm_recode" + fm_set_fsm_file_opt);
+                       Pass::call(design, "fsm_recode" + fm_set_fsm_file_opt + encoding_opt);
                Pass::call(design, "fsm_info");
 
                if (!flag_nomap)
index 063af587dbb5bd77c9d1958a310544e5c4d3d25d..b8edf420a93473b72ecefb89b5e3f67cb3d4c0f7 100644 (file)
@@ -77,27 +77,30 @@ static void implement_pattern_cache(RTLIL::Module *module, std::map<RTLIL::Const
                        and_sig.append(RTLIL::SigSpec(eq_wire));
                }
 
-               if (or_sig.width == 1)
+               if (or_sig.width < num_states-int(fullstate_cache.size()))
                {
-                       and_sig.append(or_sig);
-               }
-               else if (or_sig.width < num_states && int(it.second.size()) < num_states)
-               {
-                       RTLIL::Wire *or_wire = new RTLIL::Wire;
-                       or_wire->name = NEW_ID;
-                       module->add(or_wire);
-
-                       RTLIL::Cell *or_cell = new RTLIL::Cell;
-                       or_cell->name = NEW_ID;
-                       or_cell->type = "$reduce_or";
-                       or_cell->connections["\\A"] = or_sig;
-                       or_cell->connections["\\Y"] = RTLIL::SigSpec(or_wire);
-                       or_cell->parameters["\\A_SIGNED"] = RTLIL::Const(false);
-                       or_cell->parameters["\\A_WIDTH"] = RTLIL::Const(or_sig.width);
-                       or_cell->parameters["\\Y_WIDTH"] = RTLIL::Const(1);
-                       module->add(or_cell);
-
-                       and_sig.append(RTLIL::SigSpec(or_wire));
+                       if (or_sig.width == 1)
+                       {
+                               and_sig.append(or_sig);
+                       }
+                       else
+                       {
+                               RTLIL::Wire *or_wire = new RTLIL::Wire;
+                               or_wire->name = NEW_ID;
+                               module->add(or_wire);
+
+                               RTLIL::Cell *or_cell = new RTLIL::Cell;
+                               or_cell->name = NEW_ID;
+                               or_cell->type = "$reduce_or";
+                               or_cell->connections["\\A"] = or_sig;
+                               or_cell->connections["\\Y"] = RTLIL::SigSpec(or_wire);
+                               or_cell->parameters["\\A_SIGNED"] = RTLIL::Const(false);
+                               or_cell->parameters["\\A_WIDTH"] = RTLIL::Const(or_sig.width);
+                               or_cell->parameters["\\Y_WIDTH"] = RTLIL::Const(1);
+                               module->add(or_cell);
+
+                               and_sig.append(RTLIL::SigSpec(or_wire));
+                       }
                }
 
                switch (and_sig.width)
@@ -131,7 +134,7 @@ static void implement_pattern_cache(RTLIL::Module *module, std::map<RTLIL::Const
                        cases_vector.append(RTLIL::SigSpec(1, 1));
                        break;
                default:
-                       assert(!"This should never happen!");
+                       log_abort();
                }
        }
 
@@ -184,6 +187,9 @@ static void map_fsm(RTLIL::Cell *fsm_cell, RTLIL::Module *module)
                state_dff->type = "$adff";
                state_dff->parameters["\\ARST_POLARITY"] = fsm_cell->parameters["\\ARST_POLARITY"];
                state_dff->parameters["\\ARST_VALUE"] = fsm_data.state_table[fsm_data.reset_state];
+               for (auto &bit : state_dff->parameters["\\ARST_VALUE"].bits)
+                       if (bit != RTLIL::State::S1)
+                               bit = RTLIL::State::S0;
                state_dff->connections["\\ARST"] = fsm_cell->connections["\\ARST"];
        }
        state_dff->parameters["\\WIDTH"] = RTLIL::Const(fsm_data.state_bits);
@@ -221,8 +227,7 @@ static void map_fsm(RTLIL::Cell *fsm_cell, RTLIL::Module *module)
                }
                else
                {
-                       if (sig_b.as_bool() || sig_b.width != fsm_data.state_bits)
-                               encoding_is_onehot = false;
+                       encoding_is_onehot = false;
 
                        RTLIL::Cell *eq_cell = new RTLIL::Cell;
                        eq_cell->name = NEW_ID;
@@ -266,6 +271,7 @@ static void map_fsm(RTLIL::Cell *fsm_cell, RTLIL::Module *module)
 
        if (encoding_is_onehot)
        {
+               RTLIL::SigSpec next_state_sig(RTLIL::State::Sm, next_state_wire->width);
                for (size_t i = 0; i < fsm_data.state_table.size(); i++) {
                        RTLIL::Const state = fsm_data.state_table[i];
                        int bit_idx = -1;
@@ -273,8 +279,10 @@ static void map_fsm(RTLIL::Cell *fsm_cell, RTLIL::Module *module)
                                if (state.bits[j] == RTLIL::State::S1)
                                        bit_idx = j;
                        if (bit_idx >= 0)
-                               module->connections.push_back(RTLIL::SigSig(RTLIL::SigSpec(next_state_wire, 1, bit_idx), RTLIL::SigSpec(next_state_onehot, 1, i)));
+                               next_state_sig.replace(bit_idx, RTLIL::SigSpec(next_state_onehot, 1, i));
                }
+               log_assert(!next_state_sig.has_marked_bits());
+               module->connections.push_back(RTLIL::SigSig(next_state_wire, next_state_sig));
        }
        else
        {
index acb5944a1cb926de4a7b9ebfb4a23a2befcb8c5f..99ee0eb53654d7e3cd9e5af012d2a264a0b336c1 100644 (file)
@@ -23,6 +23,7 @@
 #include "kernel/consteval.h"
 #include "kernel/celltypes.h"
 #include "fsmdata.h"
+#include "math.h"
 #include <string.h>
 
 static void fm_set_fsm_print(RTLIL::Cell *cell, RTLIL::Module *module, FsmData &fsm_data, const char *prefix, FILE *f)
@@ -46,31 +47,50 @@ static void fm_set_fsm_print(RTLIL::Cell *cell, RTLIL::Module *module, FsmData &
                        prefix, RTLIL::unescape_id(module->name).c_str());
 }
 
-static void fsm_recode(RTLIL::Cell *cell, RTLIL::Module *module, FILE *fm_set_fsm_file)
+static void fsm_recode(RTLIL::Cell *cell, RTLIL::Module *module, FILE *fm_set_fsm_file, std::string default_encoding)
 {
+       std::string encoding = cell->attributes.count("\\fsm_encoding") ? cell->attributes.at("\\fsm_encoding").str : "auto";
+
+       log("Recoding FSM `%s' from module `%s' using `%s' encoding:\n", cell->name.c_str(), module->name.c_str(), encoding.c_str());
+       if (encoding != "none" && encoding != "one-hot" && encoding != "binary") {
+               if (encoding != "auto")
+                       log("  unkown encoding `%s': using auto (%s) instead.\n", encoding.c_str(), default_encoding.c_str());
+               encoding = default_encoding;
+       }
+
+       if (encoding == "none") {
+               log("  nothing to do for encoding `none'.\n");
+               return;
+       }
+
        FsmData fsm_data;
        fsm_data.copy_from_cell(cell);
 
-       log("Recoding FSM `%s' from module `%s':\n", cell->name.c_str(), module->name.c_str());
-
        if (fm_set_fsm_file != NULL)
                fm_set_fsm_print(cell, module, fsm_data, "r", fm_set_fsm_file);
 
-       fsm_data.state_bits = fsm_data.state_table.size();
-       if (fsm_data.reset_state >= 0)
-               fsm_data.state_bits--;
-
-       int bit_pos = 0;
-       for (size_t i = 0; i < fsm_data.state_table.size(); i++)
+       if (encoding == "one-hot") {
+               fsm_data.state_bits = fsm_data.state_table.size();
+       } else
+       if (encoding == "auto" || encoding == "binary") {
+               fsm_data.state_bits = ceil(log2(fsm_data.state_table.size()));
+       } else
+               log_error("FSM encoding `%s' is not supported!\n", encoding.c_str());
+       
+       int state_idx_counter = fsm_data.reset_state >= 0 ? 1 : 0;
+       for (int i = 0; i < int(fsm_data.state_table.size()); i++)
        {
+               int state_idx = fsm_data.reset_state == i ? 0 : state_idx_counter++;
                RTLIL::Const new_code;
-               if (int(i) == fsm_data.reset_state)
-                       new_code = RTLIL::Const(RTLIL::State::S0, fsm_data.state_bits);
-               else {
-                       RTLIL::Const state_code(RTLIL::State::Sa, fsm_data.state_bits);
-                       state_code.bits[bit_pos++] = RTLIL::State::S1;
-                       new_code = state_code;
-               }
+
+               if (encoding == "one-hot") {
+                       new_code = RTLIL::Const(RTLIL::State::Sa, fsm_data.state_bits);
+                       new_code.bits[state_idx] = RTLIL::State::S1;
+               } else
+               if (encoding == "auto" || encoding == "binary") {
+                       new_code = RTLIL::Const(state_idx, fsm_data.state_bits);
+               } else
+                       log_abort();
 
                log("  %s -> %s\n", fsm_data.state_table[i].as_string().c_str(), new_code.as_string().c_str());
                fsm_data.state_table[i] = new_code;
@@ -88,10 +108,12 @@ struct FsmRecodePass : public Pass {
        {
                //   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
                log("\n");
-               log("    fsm_recode [-fm_set_fsm_file file] [selection]\n");
+               log("    fsm_recode [-encoding type] [-fm_set_fsm_file file] [selection]\n");
                log("\n");
                log("This pass reassign the state encodings for FSM cells. At the moment only\n");
-               log("one-hot encoding is supported.\n");
+               log("one-hot encoding and binary encoding is supported. The option -encoding\n");
+               log("can be used to specify the encoding scheme used for FSMs without the\n");
+               log("`fsm_encoding' attribute (or with the attribute set to `auto'.\n");
                log("\n");
                log("The option -fm_set_fsm_file can be used to generate a file containing the\n");
                log("mapping from old to new FSM encoding in form of Synopsys Formality set_fsm_*\n");
@@ -101,6 +123,7 @@ struct FsmRecodePass : public Pass {
        virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
        {
                FILE *fm_set_fsm_file = NULL;
+               std::string default_encoding = "one-hot";
 
                log_header("Executing FSM_RECODE pass (re-assigning FSM state encoding).\n");
                size_t argidx;
@@ -112,6 +135,10 @@ struct FsmRecodePass : public Pass {
                                        log_error("Can't open fm_set_fsm_file `%s' for writing: %s\n", args[argidx].c_str(), strerror(errno));
                                continue;
                        }
+                       if (arg == "-encoding" && argidx+1 < args.size() && fm_set_fsm_file == NULL) {
+                               default_encoding = args[++argidx];
+                               continue;
+                       }
                        break;
                }
                extra_args(args, argidx, design);
@@ -120,7 +147,7 @@ struct FsmRecodePass : public Pass {
                        if (design->selected(mod_it.second))
                                for (auto &cell_it : mod_it.second->cells)
                                        if (cell_it.second->type == "$fsm" && design->selected(mod_it.second, cell_it.second))
-                                               fsm_recode(cell_it.second, mod_it.second, fm_set_fsm_file);
+                                               fsm_recode(cell_it.second, mod_it.second, fm_set_fsm_file, default_encoding);
 
                if (fm_set_fsm_file != NULL)
                        fclose(fm_set_fsm_file);