From 77183899e0526a343b8429cf04a1c07b31aafc34 Mon Sep 17 00:00:00 2001
From: Scott Mansell <phiren@gmail.com>
Date: Wed, 1 Jul 2015 00:37:26 +1200
Subject: [PATCH] evdev: Support axis with ranges which extend below zero.

---
 .../InputCommon/ControllerInterface/evdev/evdev.cpp  | 12 +++++++++---
 .../InputCommon/ControllerInterface/evdev/evdev.h    |  1 +
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/Source/Core/InputCommon/ControllerInterface/evdev/evdev.cpp b/Source/Core/InputCommon/ControllerInterface/evdev/evdev.cpp
index 2f4d53e234..9b31da73c4 100644
--- a/Source/Core/InputCommon/ControllerInterface/evdev/evdev.cpp
+++ b/Source/Core/InputCommon/ControllerInterface/evdev/evdev.cpp
@@ -164,7 +164,8 @@ ControlState evdevDevice::Button::GetState() const
 evdevDevice::Axis::Axis(u8 index, u16 code, bool upper, libevdev* dev) :
 	m_code(code), m_index(index), m_upper(upper), m_dev(dev)
 {
-	m_range = libevdev_get_abs_maximum(m_dev, m_code);
+	m_min = libevdev_get_abs_minimum(m_dev, m_code);
+	m_range = libevdev_get_abs_maximum(m_dev, m_code) + abs(m_min);
 }
 
 std::string evdevDevice::Axis::GetName() const
@@ -176,10 +177,15 @@ ControlState evdevDevice::Axis::GetState() const
 {
 	int value = 0;
 	libevdev_fetch_event_value(m_dev, EV_ABS, m_code, &value);
+
+	// Value from 0.0 to 1.0
+	ControlState fvalue = double(value - m_min) / double(m_range);
+
+	// Split into two axis, each covering half the range from 0.0 to 1.0
 	if (m_upper)
-		return std::max(0.0, double(value) / double(m_range) - 0.5) * 2.0;
+		return std::max(0.0, fvalue - 0.5) * 2.0;
 	else
-		return (0.5 - std::min(0.5, double(value) / double(m_range))) * 2.0;
+		return (0.5 - std::min(0.5, fvalue)) * 2.0;
 }
 
 std::string evdevDevice::ForceFeedback::GetName() const
diff --git a/Source/Core/InputCommon/ControllerInterface/evdev/evdev.h b/Source/Core/InputCommon/ControllerInterface/evdev/evdev.h
index 7290fbc379..d1555c8cce 100644
--- a/Source/Core/InputCommon/ControllerInterface/evdev/evdev.h
+++ b/Source/Core/InputCommon/ControllerInterface/evdev/evdev.h
@@ -43,6 +43,7 @@ private:
 		const u8 m_index;
 		const bool m_upper;
 		int m_range;
+		int m_min;
 		libevdev* m_dev;
 	};