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authorGravatarGravatar antonioginer <antonioginer@users.noreply.github.com>2019-11-16 22:06:13 +0100
committerGravatarGravatar R. Belmont <rb6502@users.noreply.github.com>2019-11-16 16:06:13 -0500
commiteab5bcac0029e4e298e1f194133c21580098508d (patch)
tree6f7f3fd423089b85f15b09956ce7912f180bed0b /src/emu
parent7fc2f6805118f1e25c5e0b2a971f31e4f1b3b251 (diff)
Remove up to one frame of input latency. (#5901)
* Remove up to one frame of input latency. Makes MAME virtually lagless on VRR monitors. * Use empty parentheses and clean interface member calls * Add new option -instant_blit to make this feature optional * Rename new option to -lowlatency, -ll
Diffstat (limited to 'src/emu')
-rw-r--r--src/emu/emuopts.cpp1
-rw-r--r--src/emu/emuopts.h2
-rw-r--r--src/emu/video.cpp10
-rw-r--r--src/emu/video.h1
4 files changed, 13 insertions, 1 deletions
diff --git a/src/emu/emuopts.cpp b/src/emu/emuopts.cpp
index eb7c9bdbf27..8af8541d32c 100644
--- a/src/emu/emuopts.cpp
+++ b/src/emu/emuopts.cpp
@@ -88,6 +88,7 @@ const options_entry emu_options::s_option_entries[] =
{ OPTION_SLEEP, "1", OPTION_BOOLEAN, "enable sleeping, which gives time back to other applications when idle" },
{ OPTION_SPEED "(0.01-100)", "1.0", OPTION_FLOAT, "controls the speed of gameplay, relative to realtime; smaller numbers are slower" },
{ OPTION_REFRESHSPEED ";rs", "0", OPTION_BOOLEAN, "automatically adjust emulation speed to keep the emulated refresh rate slower than the host screen" },
+ { OPTION_LOWLATENCY ";ll", "0", OPTION_BOOLEAN, "draws new frame before throttling to reduce input latency" },
// render options
{ nullptr, nullptr, OPTION_HEADER, "CORE RENDER OPTIONS" },
diff --git a/src/emu/emuopts.h b/src/emu/emuopts.h
index 970a90c67da..a1a23e77a2b 100644
--- a/src/emu/emuopts.h
+++ b/src/emu/emuopts.h
@@ -75,6 +75,7 @@
#define OPTION_SLEEP "sleep"
#define OPTION_SPEED "speed"
#define OPTION_REFRESHSPEED "refreshspeed"
+#define OPTION_LOWLATENCY "lowlatency"
// core render options
#define OPTION_KEEPASPECT "keepaspect"
@@ -352,6 +353,7 @@ public:
bool sleep() const { return m_sleep; }
float speed() const { return float_value(OPTION_SPEED); }
bool refresh_speed() const { return m_refresh_speed; }
+ bool low_latency() const { return bool_value(OPTION_LOWLATENCY); }
// core render options
bool keep_aspect() const { return bool_value(OPTION_KEEPASPECT); }
diff --git a/src/emu/video.cpp b/src/emu/video.cpp
index d8bea693005..fa0efb88a89 100644
--- a/src/emu/video.cpp
+++ b/src/emu/video.cpp
@@ -91,6 +91,7 @@ video_manager::video_manager(running_machine &machine)
, m_seconds_to_run(machine.options().seconds_to_run())
, m_auto_frameskip(machine.options().auto_frameskip())
, m_speed(original_speed_setting())
+ , m_low_latency(machine.options().low_latency())
, m_empty_skip_count(0)
, m_frameskip_level(machine.options().frameskip())
, m_frameskip_counter(0)
@@ -229,7 +230,7 @@ void video_manager::frame_update(bool from_debugger)
// if we're throttling, synchronize before rendering
attotime current_time = machine().time();
- if (!from_debugger && !skipped_it && effective_throttle())
+ if (!from_debugger && !skipped_it && !m_low_latency && effective_throttle())
update_throttle(current_time);
// ask the OSD to update
@@ -237,6 +238,13 @@ void video_manager::frame_update(bool from_debugger)
machine().osd().update(!from_debugger && skipped_it);
g_profiler.stop();
+ // we synchronize after rendering instead of before, if low latency mode is enabled
+ if (!from_debugger && !skipped_it && m_low_latency && effective_throttle())
+ update_throttle(current_time);
+
+ // get most recent input now
+ machine().osd().input_update();
+
emulator_info::periodic_check();
// perform tasks for this frame
diff --git a/src/emu/video.h b/src/emu/video.h
index b8b1c408773..5ccfe2b99b0 100644
--- a/src/emu/video.h
+++ b/src/emu/video.h
@@ -163,6 +163,7 @@ private:
u32 m_seconds_to_run; // number of seconds to run before quitting
bool m_auto_frameskip; // flag: true if we're automatically frameskipping
u32 m_speed; // overall speed (*1000)
+ bool m_low_latency; // flag: true if we are throttling after blitting
// frameskipping
u8 m_empty_skip_count; // number of empty frames we have skipped