From fdc9f38a8ee3e520339af0409bc7ced172a8acf9 Mon Sep 17 00:00:00 2001
From: Vas Crabb <vas@vastheman.com>
Date: Mon, 25 Jun 2018 14:35:04 +1000
Subject: [PATCH] consider double epsilon when comapring crystal values

---
 src/emu/xtal.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/emu/xtal.cpp b/src/emu/xtal.cpp
index b48ba2791c6..3c1f71d7cac 100644
--- a/src/emu/xtal.cpp
+++ b/src/emu/xtal.cpp
@@ -48,6 +48,9 @@
 
 #include "emu.h"
 
+#include <cfloat>
+#include <cmath>
+
 
 // This array *must* stay in order, it's binary-searched
 const double XTAL::known_xtals[] = {
@@ -380,8 +383,9 @@ bool XTAL::validate(double base_clock)
 		if(slot > last_index)
 			slot = slot ^ (step | (step >> 1));
 		else {
-			double sfreq = known_xtals[slot];
-			if(base_clock == sfreq) {
+			const double sfreq = known_xtals[slot];
+			const double diff = std::abs((base_clock - sfreq) / base_clock);
+			if(diff <= (2 * DBL_EPSILON)) {
 				last_correct_value = base_clock;
 				return true;
 			}