From: Clifford Wolf <clifford@clifford.at>
Date: Sat, 30 Aug 2014 12:43:06 +0000 (+0200)
Subject: Don't change existing binary FSM encoding if it is already optimal
X-Git-Tag: yosys-0.4~199
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=3a7d5d188d4b9cfeb225e0f5dea07ee7a40eceed;p=yosys.git

Don't change existing binary FSM encoding if it is already optimal
---

diff --git a/passes/fsm/fsm_recode.cc b/passes/fsm/fsm_recode.cc
index 9c0da0a37..ea10cdf80 100644
--- a/passes/fsm/fsm_recode.cc
+++ b/passes/fsm/fsm_recode.cc
@@ -82,7 +82,12 @@ static void fsm_recode(RTLIL::Cell *cell, RTLIL::Module *module, FILE *fm_set_fs
 		fsm_data.state_bits = fsm_data.state_table.size();
 	} else
 	if (encoding == "binary") {
-		fsm_data.state_bits = ceil(log2(fsm_data.state_table.size()));
+		int new_num_state_bits = ceil(log2(fsm_data.state_table.size()));
+		if (fsm_data.state_bits == new_num_state_bits) {
+			log("  existing encoding is already a packed binary encoding.\n");
+			return;
+		}
+		fsm_data.state_bits = new_num_state_bits;
 	} else
 		log_error("FSM encoding `%s' is not supported!\n", encoding.c_str());