From e7580a2f4fc66b87cb24c69456326bcc5a584558 Mon Sep 17 00:00:00 2001
From: Cassie Jones <code@witchoflight.com>
Date: Sat, 7 Mar 2020 00:04:33 +0100
Subject: [PATCH] Add -nosynth flag to skip internal synthesis

This is useful if you want to have control the initial coarse-grained
synthesis, you can disable the synthesis that synth_nan does and provide
your own.
---
 nangate.cc | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/nangate.cc b/nangate.cc
index 673e294..de0111a 100644
--- a/nangate.cc
+++ b/nangate.cc
@@ -7,10 +7,6 @@
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
-static bool is_width(const string &arg) {
-    return arg == "-w" or arg == "-width" or arg == "--width";
-}
-
 struct NandToNaNWorker
 {
     int nand_count = 0, not_count = 0, b2f_count = 0, f2b_count = 0;
@@ -84,7 +80,7 @@ struct NandToNaNPass : public Pass {
         int width = 3;
         size_t argidx = 1;
         for (; argidx < args.size(); ++argidx) {
-            if (is_width(args[argidx]) and argidx + 1 < args.size()) {
+            if (args[argidx] == "-width" and argidx + 1 < args.size()) {
                 try {
                     width = std::stoi(args[++argidx]);
                 } catch (...) {
@@ -115,7 +111,7 @@ struct DffToFpPass : public Pass {
         int width = 3;
         size_t argidx = 1;
         for (; argidx < args.size(); ++argidx) {
-            if (is_width(args[argidx]) and argidx + 1 < args.size()) {
+            if (args[argidx] == "-width" and argidx + 1 < args.size()) {
                 try {
                     width = std::stoi(args[++argidx]);
                 } catch (...) {
@@ -223,9 +219,13 @@ struct SynthNaN : public Pass {
         log("    -width <width>");
         log("        synthesize with a given floating-point with (default=3)");
         log("");
+        log("    -nosynth <width>");
+        log("        skip the pre-run synthesis step. Requires that the circuit");
+        log("        has already been synthesized down to NAND and NOT gates.");
+        log("");
         log("Runs the equivalent of the following script:\n\n");
-        log("    synth [-top <module>]\n");
-        log("    abc -g NAND\n");
+        log("    synth [-top <module>]          (unless -nosynth)\n");
+        log("    abc -g NAND                    (unless -nosynth)\n");
         log("    nand_to_nan [-width <width>]\n");
         log("    share_nan\n");
         log("    dff_nan [-width <width>]\n");
@@ -240,23 +240,30 @@ struct SynthNaN : public Pass {
         log_push();
 
         size_t argidx = 1;
+        bool synth = true;
         for (; argidx < args.size(); ++argidx) {
             if (args[argidx] == "-top" and argidx + 1 < args.size()) {
                 synth_args += " -top ";
                 synth_args += args[++argidx];
                 continue;
             }
-            if (is_width(args[argidx]) and argidx + 1 < args.size()) {
-                width_args += " --width ";
+            if (args[argidx] == "-width" and argidx + 1 < args.size()) {
+                width_args += " -width ";
                 width_args += args[++argidx];
                 continue;
             }
+            if (args[argidx] == "-nosynth") {
+                synth = false;
+                continue;
+            }
             break;
         }
         extra_args(args, argidx, design, false);
 
-        Pass::call(design, "synth" + synth_args);
-        Pass::call(design, "abc -g NAND");
+        if (synth) {
+            Pass::call(design, "synth" + synth_args);
+            Pass::call(design, "abc -g NAND");
+        }
         Pass::call(design, "nand_to_nan" + width_args);
         Pass::call(design, "share_nan");
         Pass::call(design, "dff_nan" + width_args);
-- 
2.47.0