From ccf36cb7d81a9513db15b8a36c240d2c7ec9f5b5 Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Sun, 11 Aug 2013 16:27:15 +0200
Subject: [PATCH] Added SAT support for $div and $mod cells

---
 kernel/satgen.h     | 46 +++++++++++++++++++++++++++++++++++++++++++++
 libs/ezsat/ezsat.cc |  6 ++++++
 libs/ezsat/ezsat.h  |  3 +++
 3 files changed, 55 insertions(+)

diff --git a/kernel/satgen.h b/kernel/satgen.h
index 26e3fd7ec..b2f8b15b7 100644
--- a/kernel/satgen.h
+++ b/kernel/satgen.h
@@ -267,6 +267,52 @@ struct SatGen
 			return true;
 		}
 
+		if (cell->type == "$div" || cell->type == "$mod")
+		{
+			std::vector<int> a = importSigSpec(cell->connections.at("\\A"), timestep);
+			std::vector<int> b = importSigSpec(cell->connections.at("\\B"), timestep);
+			std::vector<int> y = importSigSpec(cell->connections.at("\\Y"), timestep);
+			extendSignalWidth(a, b, y, cell);
+
+			std::vector<int> a_u, b_u;
+			if (cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool()) {
+				a_u = ez->vec_ite(a.back(), ez->vec_neg(a), a);
+				b_u = ez->vec_ite(b.back(), ez->vec_neg(b), b);
+			} else {
+				a_u = a;
+				b_u = b;
+			}
+
+			std::vector<int> chain_buf = a_u;
+			std::vector<int> y_u(a_u.size(), ez->FALSE);
+			for (int i = int(a.size())-1; i >= 0; i--)
+			{
+				chain_buf.insert(chain_buf.end(), chain_buf.size(), ez->FALSE);
+
+				std::vector<int> b_shl(i, ez->FALSE);
+				b_shl.insert(b_shl.end(), b_u.begin(), b_u.end());
+				b_shl.insert(b_shl.end(), chain_buf.size()-b_shl.size(), ez->FALSE);
+
+				y_u.at(i) = ez->vec_ge_unsigned(chain_buf, b_shl);
+				chain_buf = ez->vec_ite(y_u.at(i), ez->vec_sub(chain_buf, b_shl), chain_buf);
+
+				chain_buf.erase(chain_buf.begin() + a_u.size(), chain_buf.end());
+			}
+
+			if (cell->type == "$div") {
+				if (cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool())
+					ez->assume(ez->vec_eq(y, ez->vec_ite(ez->XOR(a.back(), b.back()), ez->vec_neg(y_u), y_u)));
+				else
+					ez->assume(ez->vec_eq(y, y_u));
+			} else {
+				if (cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool())
+					ez->assume(ez->vec_eq(y, ez->vec_ite(a.back(), ez->vec_neg(chain_buf), chain_buf)));
+				else
+					ez->assume(ez->vec_eq(y, chain_buf));
+			}
+			return true;
+		}
+
 		if (timestep > 0 && (cell->type == "$dff" || cell->type == "$_DFF_N_" || cell->type == "$_DFF_P_")) {
 			if (timestep == 1) {
 				initial_state.add((*sigmap)(cell->connections.at("\\Q")));
diff --git a/libs/ezsat/ezsat.cc b/libs/ezsat/ezsat.cc
index 00918f62f..4258fb6fe 100644
--- a/libs/ezsat/ezsat.cc
+++ b/libs/ezsat/ezsat.cc
@@ -852,6 +852,12 @@ std::vector<int> ezSAT::vec_sub(const std::vector<int> &vec1, const std::vector<
 	return vec;
 }
 
+std::vector<int> ezSAT::vec_neg(const std::vector<int> &vec)
+{
+	std::vector<int> zero(vec.size(), FALSE);
+	return vec_sub(zero, vec);
+}
+
 void ezSAT::vec_cmp(const std::vector<int> &vec1, const std::vector<int> &vec2, int &carry, int &overflow, int &sign, int &zero)
 {
 	assert(vec1.size() == vec2.size());
diff --git a/libs/ezsat/ezsat.h b/libs/ezsat/ezsat.h
index 2d0307d51..4a6a72785 100644
--- a/libs/ezsat/ezsat.h
+++ b/libs/ezsat/ezsat.h
@@ -223,6 +223,7 @@ public:
 	std::vector<int> vec_count(const std::vector<int> &vec, int bits, bool clip = true);
 	std::vector<int> vec_add(const std::vector<int> &vec1, const std::vector<int> &vec2);
 	std::vector<int> vec_sub(const std::vector<int> &vec1, const std::vector<int> &vec2);
+	std::vector<int> vec_neg(const std::vector<int> &vec);
 
 	void vec_cmp(const std::vector<int> &vec1, const std::vector<int> &vec2, int &carry, int &overflow, int &sign, int &zero);
 
@@ -305,6 +306,8 @@ struct ezSATvec
 	ezSATvec(ezSAT &sat, const std::vector<int> &vec) : sat(sat), vec(vec) { }
 
 	ezSATvec operator ~() { return ezSATvec(sat, sat.vec_not(vec)); }
+	ezSATvec operator -() { return ezSATvec(sat, sat.vec_neg(vec)); }
+
 	ezSATvec operator &(const ezSATvec &other) { return ezSATvec(sat, sat.vec_and(vec, other.vec)); }
 	ezSATvec operator |(const ezSATvec &other) { return ezSATvec(sat, sat.vec_or(vec, other.vec)); }
 	ezSATvec operator ^(const ezSATvec &other) { return ezSATvec(sat, sat.vec_xor(vec, other.vec)); }
-- 
2.30.2