From 442a8e2875eab679ed3b31aee3d9725b87dbf4fc Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Sat, 14 Jun 2014 08:51:22 +0200
Subject: [PATCH] Implemented basic real arithmetic

---
 frontends/ast/ast.cc      | 31 ++++++++++++++++++++++++++++++-
 frontends/ast/ast.h       |  4 ++++
 frontends/ast/simplify.cc | 22 +++++++++++++++++-----
 3 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/frontends/ast/ast.cc b/frontends/ast/ast.cc
index 1ce7efc84..3af08b9d1 100644
--- a/frontends/ast/ast.cc
+++ b/frontends/ast/ast.cc
@@ -32,7 +32,7 @@
 
 #include <sstream>
 #include <stdarg.h>
-#include <assert.h>
+#include <math.h>
 
 using namespace AST;
 using namespace AST_INTERNAL;
@@ -760,6 +760,35 @@ bool AstNode::asBool()
 	return false;
 }
 
+int AstNode::isConst()
+{
+	if (type == AST_CONSTANT)
+		return 1;
+	if (type == AST_REALVALUE)
+		return 2;
+	return 0;
+}
+
+double AstNode::asReal(bool is_signed)
+{
+	if (type == AST_CONSTANT) {
+		RTLIL::Const val;
+		val.bits = bits;
+
+		double p = exp2(val.bits.size()-32);
+		if (val.bits.size() > 32)
+			val.bits.erase(val.bits.begin(), val.bits.begin()+(val.bits.size()-32));
+		int32_t v = val.as_int() << (32-val.bits.size());
+
+		if (is_signed)
+			return v * p;
+		return uint32_t(v) * p;
+	}
+	if (type == AST_REALVALUE)
+		return realvalue;
+	return 0;
+}
+
 // create a new AstModule from an AST_MODULE AST node
 static AstModule* process_module(AstNode *ast, bool defer)
 {
diff --git a/frontends/ast/ast.h b/frontends/ast/ast.h
index aeb56e352..95f0f142f 100644
--- a/frontends/ast/ast.h
+++ b/frontends/ast/ast.h
@@ -240,6 +240,10 @@ namespace AST
 		RTLIL::Const asAttrConst();
 		RTLIL::Const asParaConst();
 		bool asBool();
+
+		// helper functions for real valued const eval
+		int isConst(); // return '1' for AST_CONSTANT and '2' for AST_REALVALUE
+		double asReal(bool is_signed);
 	};
 
 	// process an AST tree (ast must point to an AST_DESIGN node) and generate RTLIL code
diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index fc040baac..7e4c265bd 100644
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -32,7 +32,7 @@
 
 #include <sstream>
 #include <stdarg.h>
-#include <assert.h>
+#include <math.h>
 
 using namespace AST;
 using namespace AST_INTERNAL;
@@ -1433,10 +1433,22 @@ skip_dynamic_range_lvalue_expansion:;
 		if (0) { case AST_MUL: const_func = RTLIL::const_mul; }
 		if (0) { case AST_DIV: const_func = RTLIL::const_div; }
 		if (0) { case AST_MOD: const_func = RTLIL::const_mod; }
-			if (children[0]->type == AST_CONSTANT && children[1]->type == AST_CONSTANT) {
-				RTLIL::Const y = const_func(children[0]->bitsAsConst(width_hint, sign_hint),
-						children[1]->bitsAsConst(width_hint, sign_hint), sign_hint, sign_hint, width_hint);
-				newNode = mkconst_bits(y.bits, sign_hint);
+			if (children[0]->isConst() && children[1]->isConst()) {
+				if (children[0]->isConst() + children[1]->isConst() > 2) {
+					newNode = new AstNode(AST_REALVALUE);
+					switch (type) {
+					case AST_ADD: newNode->realvalue = children[0]->asReal(sign_hint) + children[1]->asReal(sign_hint); break;
+					case AST_SUB: newNode->realvalue = children[0]->asReal(sign_hint) - children[1]->asReal(sign_hint); break;
+					case AST_MUL: newNode->realvalue = children[0]->asReal(sign_hint) * children[1]->asReal(sign_hint); break;
+					case AST_DIV: newNode->realvalue = children[0]->asReal(sign_hint) / children[1]->asReal(sign_hint); break;
+					case AST_MOD: newNode->realvalue = fmod(children[0]->asReal(sign_hint), children[1]->asReal(sign_hint)); break;
+					default: log_abort();
+					}
+				} else {
+					RTLIL::Const y = const_func(children[0]->bitsAsConst(width_hint, sign_hint),
+							children[1]->bitsAsConst(width_hint, sign_hint), sign_hint, sign_hint, width_hint);
+					newNode = mkconst_bits(y.bits, sign_hint);
+				}
 			}
 			break;
 		if (0) { case AST_POS: const_func = RTLIL::const_pos; }
-- 
2.30.2