From b3a7f8f1fceddcd45ec62bcbf75ba128e4f84f5a Mon Sep 17 00:00:00 2001
From: Nebuleon Fumika
Date: Sun, 3 Feb 2013 19:26:34 -0500
Subject: Synchronise the controller status more spread out inside a rendered
 frame: * before rendering a background; * before rendering sprites; * while
 rendering more than 128 samples of audio at once ("Prefer fluid video"); *
 after every 16 scanlines of CPU execution instead of every 1; * while waiting
 for an audio buffer to become available; * while killing time between frames
 with fast-forward disabled.

Controller presses and releases are now combined in a DS button bitfield using a shorter 32-bit algorithm. See entry.cpp:NDSSFCAccumulateJoypad and #define ACCUMULATE_JOYPAD in the source.

This is still not suitable for playing platformers frame-perfectly, but it's much better than half a second of latency to press or release a button, and one still needs to press buttons a bit more than just light taps. I'd say 50 milliseconds is the latency now. Platformers requiring more precision can be played with frameskip 0.

DMA does not require double-buffered displaying, so synchronise the controller more often by disabling double-buffered displaying again.
---
 source/cpuexec.cpp | 35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

(limited to 'source/cpuexec.cpp')

diff --git a/source/cpuexec.cpp b/source/cpuexec.cpp
index a0c7ebc..30dff21 100644
--- a/source/cpuexec.cpp
+++ b/source/cpuexec.cpp
@@ -105,7 +105,7 @@
 #include "sa1.h"
 #include "spc7110.h"
 
-#ifdef SYNC_JOYPAD_AT_HBLANK
+#ifdef ACCUMULATE_JOYPAD
 #include "display.h"
 #endif
 
@@ -473,15 +473,14 @@ void S9xDoHBlankProcessing_SFX ()
     switch (CPU.WhichEvent)
     {
 		case HBLANK_START_EVENT:
-#ifdef SYNC_JOYPAD_AT_HBLANK
-		// Re-get the controls every hblank. A resolution algorithm in
-		// ppu.cpp will determine with greater accuracy whether a key was
-		// pressed or released during the frame.
-		uint32 i;
-		for (i = 0; i < 5; i++)
-		{
-			IPPU.JoypadsAtHBlanks [i][CPU.V_Counter] = S9xReadJoypad (i);
-		}
+#ifdef ACCUMULATE_JOYPAD
+/*
+ * This call allows NDSSFC to synchronise the DS controller more often.
+ * If porting a later version of Snes9x into NDSSFC, it is essential to
+ * preserve it.
+ */
+		if ((CPU.V_Counter & 0xF) == 0)
+			NDSSFCAccumulateJoypad ();
 #endif
 		if (IPPU.HDMA && CPU.V_Counter <= PPU.ScreenHeight)
 			IPPU.HDMA = S9xDoHDMA (IPPU.HDMA);
@@ -663,15 +662,13 @@ void S9xDoHBlankProcessing_NoSFX ()
     switch (CPU.WhichEvent)
     {
 		case HBLANK_START_EVENT:
-#ifdef SYNC_JOYPAD_AT_HBLANK
-		// Re-get the controls every hblank. A resolution algorithm in
-		// ppu.cpp will determine with greater accuracy whether a key was
-		// pressed or released during the frame.
-		uint32 i;
-		for (i = 0; i < 5; i++)
-		{
-			IPPU.JoypadsAtHBlanks [i][CPU.V_Counter] = S9xReadJoypad (i);
-		}
+#ifdef ACCUMULATE_JOYPAD
+/*
+ * This call allows NDSSFC to synchronise the DS controller more often.
+ * If porting a later version of Snes9x into NDSSFC, it is essential to
+ * preserve it.
+ */
+		NDSSFCAccumulateJoypad ();
 #endif
 		if (IPPU.HDMA && CPU.V_Counter <= PPU.ScreenHeight)
 			IPPU.HDMA = S9xDoHDMA (IPPU.HDMA);
-- 
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