Some improvements in FSM mapping and recoding

diff --git a/passes/fsm/fsm_map.cc b/passes/fsm/fsm_map.cc
index 048cf7e5fa9b13ada0427e105a9c37770ee0dae0..60580eb4689acdfe0fb9ebeede140d20d5849b60 100644 (file)
--- a/passes/fsm/fsm_map.cc
+++ b/passes/fsm/fsm_map.cc
@@ -285,7 +285,7 @@ static void map_fsm(RTLIL::Cell *fsm_cell, RTLIL::Module *module)
                                }
                        }
 
-                       RTLIL::Cell *mux_cell = module->addCell(NEW_ID, "$safe_pmux");
+                       RTLIL::Cell *mux_cell = module->addCell(NEW_ID, "$pmux");
                        mux_cell->setPort("\\A", sig_a);
                        mux_cell->setPort("\\B", sig_b);
                        mux_cell->setPort("\\S", sig_s);

diff --git a/passes/fsm/fsm_recode.cc b/passes/fsm/fsm_recode.cc
index 40fed130e8bf628e91038c15538e3f8910839de7..9c0da0a37c87de86fb8d5d9a0731c7985b30ea0a 100644 (file)
--- a/passes/fsm/fsm_recode.cc
+++ b/passes/fsm/fsm_recode.cc
@@ -53,10 +53,10 @@ static void fsm_recode(RTLIL::Cell *cell, RTLIL::Module *module, FILE *fm_set_fs
        std::string encoding = cell->attributes.count("\\fsm_encoding") ? cell->attributes.at("\\fsm_encoding").decode_string() : "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" && encoding != "one-hot" && encoding != "binary" && encoding != "auto") {
+               log("  unkown encoding `%s': using auto instead.\n", encoding.c_str());
+               encoding = "auto";
        }
 
        if (encoding == "none") {
@@ -70,10 +70,18 @@ static void fsm_recode(RTLIL::Cell *cell, RTLIL::Module *module, FILE *fm_set_fs
        if (fm_set_fsm_file != NULL)
                fm_set_fsm_print(cell, module, fsm_data, "r", fm_set_fsm_file);
 
+       if (encoding == "auto") {
+               if (!default_encoding.empty())
+                       encoding = default_encoding;
+               else
+                       encoding = SIZE(fsm_data.state_table) < 32 ? "one-hot" : "binary";
+               log("  mapping auto encoding to `%s` for this FSM.\n", encoding.c_str());
+       }
+
        if (encoding == "one-hot") {
                fsm_data.state_bits = fsm_data.state_table.size();
        } else
-       if (encoding == "auto" || encoding == "binary") {
+       if (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());
@@ -88,7 +96,7 @@ static void fsm_recode(RTLIL::Cell *cell, RTLIL::Module *module, FILE *fm_set_fs
                        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") {
+               if (encoding == "binary") {
                        new_code = RTLIL::Const(state_idx, fsm_data.state_bits);
                } else
                        log_abort();
@@ -124,7 +132,7 @@ 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";
+               std::string default_encoding;
 
                log_header("Executing FSM_RECODE pass (re-assigning FSM state encoding).\n");
                size_t argidx;

diff --git a/tests/fsm/generate.py b/tests/fsm/generate.py
index 66ca2af5e2ed067688e8f781890e896cd01d347f..b5b4626dfb8e95b8a1b5bde50d3f986377031cea 100644 (file)
--- a/tests/fsm/generate.py
+++ b/tests/fsm/generate.py
@@ -52,7 +52,8 @@ for idx in range(50):
         print('  output reg%s [%d:0] y;' % (random.choice(['', ' signed']), random.randint(0, 31)))
         print('  output reg%s [%d:0] z;' % (random.choice(['', ' signed']), random.randint(0, 31)))
         state_bits = random.randint(5, 16);
-        print('  reg [%d:0] state;' % (state_bits-1))
+        print('  %sreg [%d:0] state;' % (random.choice(['', '(* fsm_encoding = "one-hot" *)',
+                '(* fsm_encoding = "binary" *)']), state_bits-1))
         states=[]
         for i in range(random.randint(2, 10)):
             n = random.randint(0, 2**state_bits-1)