From 7d33fd463b2291954c7f9ca1f2dbeff3843a63ea Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Thu, 13 Feb 2025 11:11:33 -0800
Subject: [PATCH] Add is_mostly_const to SigSpec

---
 kernel/rtlil.cc | 12 ++++++++++++
 kernel/rtlil.h  |  1 +
 2 files changed, 13 insertions(+)

diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index 97968b5f5..8f3a72e6f 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -5164,6 +5164,18 @@ bool RTLIL::SigSpec::is_chunk() const
 	return GetSize(chunks_) == 1;
 }
 
+bool RTLIL::SigSpec::is_mostly_const() const
+{
+	cover("kernel.rtlil.sigspec.is_mostly_const");
+
+	pack();
+	int constbits = 0;
+	for (auto it = chunks_.begin(); it != chunks_.end(); it++)
+		if (it->width > 0 && it->wire == NULL)
+			constbits += it->width;
+	return (constbits > width_/2);
+}
+
 bool RTLIL::SigSpec::is_fully_const() const
 {
 	cover("kernel.rtlil.sigspec.is_fully_const");
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 4ddce7d25..f77869a82 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -1094,6 +1094,7 @@ public:
 	bool is_chunk() const;
 	inline bool is_bit() const { return width_ == 1; }
 
+	bool is_mostly_const() const;
 	bool is_fully_const() const;
 	bool is_fully_zero() const;
 	bool is_fully_ones() const;