From a19dddf05eb029fa20e7b65ebc61b55782b08a09 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Sat, 28 Jan 2023 22:11:09 -0500
Subject: [PATCH] Fix real parameters of infinity and NaN.

---
 Changes                      |  1 +
 src/V3EmitCFunc.cpp          |  6 ++++++
 test_regress/t/t_math_real.v | 21 ++++++++++++++++++++-
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/Changes b/Changes
index a4e2ea12d..8782e98b2 100644
--- a/Changes
+++ b/Changes
@@ -16,6 +16,7 @@ Verilator 5.007 devel
 * Support unpacked unions.
 * Support interface classes and class implements.
 * Support global clocking and $global_clock.
+* Fix real parameters of infinity and NaN.
 
 
 Verilator 5.006 2022-01-22
diff --git a/src/V3EmitCFunc.cpp b/src/V3EmitCFunc.cpp
index 2922d6706..885392513 100644
--- a/src/V3EmitCFunc.cpp
+++ b/src/V3EmitCFunc.cpp
@@ -541,6 +541,12 @@ void EmitCFunc::emitConstant(AstConst* nodep, AstVarRef* assigntop, const string
         if (int(nodep->num().toDouble()) == nodep->num().toDouble()
             && nodep->num().toDouble() < 1000 && nodep->num().toDouble() > -1000) {
             ofp()->printf("%3.1f", nodep->num().toDouble());  // Force decimal point
+        } else if (std::isinf(nodep->num().toDouble())) {
+            if (std::signbit(nodep->num().toDouble())) puts("-");
+            ofp()->puts("std::numeric_limits<double>::infinity()");
+        } else if (std::isnan(nodep->num().toDouble())) {
+            if (std::signbit(nodep->num().toDouble())) puts("-");
+            ofp()->puts("std::numeric_limits<double>::quiet_NaN()");
         } else {
             // Not %g as will not always put in decimal point, so not obvious to compiler
             // is a real number
diff --git a/test_regress/t/t_math_real.v b/test_regress/t/t_math_real.v
index 856547a66..8798f1cdb 100644
--- a/test_regress/t/t_math_real.v
+++ b/test_regress/t/t_math_real.v
@@ -6,7 +6,9 @@
 // Version 2.0.
 // SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 
-`define checkr(gotv,expv) do if ((gotv) != (expv)) begin $write("%%Error: %s:%0d:  got=%f exp=%f\n", `__FILE__,`__LINE__, (gotv), (expv)); $stop; end while(0);
+`define stop $stop
+`define checkr(gotv,expv) do if ((gotv) != (expv)) begin $write("%%Error: %s:%0d:  got=%f exp=%f\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
+`define checks(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got='%s' exp='%s'\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
 `define is_near_real(a,b)  (( ((a)<(b)) ? (b)-(a) : (a)-(b)) < (((a)/(b))*0.0001))
 
 module t (/*AUTOARG*/
@@ -29,6 +31,7 @@ module t (/*AUTOARG*/
    reg signed [95:0] cis96;
    real  r, r2;
    integer      cyc = 0;
+   string       s;
 
    realtime  uninit;
    initial if (uninit != 0.0) $stop;
@@ -134,6 +137,22 @@ module t (/*AUTOARG*/
       if (r != 74276402357122816493947453440.0) $stop;
       r = real'(96'shf0000000_00000000_00000000);
       if (r != -4951760157141521099596496896.0) $stop;
+
+      r = 1.23456;
+      s = $sformatf("%g", r);
+      `checks(s, "1.23456");
+      r = 1.0/0;  // inf
+      s = $sformatf("%g", r);
+      `checks(s, "inf");
+      r = -1.0/0;  // -inf
+      s = $sformatf("%g", r);
+      `checks(s, "-inf");
+      r = $sqrt(-1.0);  // NaN
+      s = $sformatf("%g", r);
+      `checks(s, "-nan");
+      r = -$sqrt(-1.0);  // NaN
+      s = $sformatf("%g", r);
+      `checks(s, "nan");
    end
 
    // Test loop