Add overclocking - backported from FCEUX with mods

src/drivers/libretro/libretro.c

@@ -22,8 +22,8 @@
 #include "../../unif.h"
 #include "../../fds.h"
 #include "../../vsuni.h"
+#include "../../video.h"
 
-#include <string.h>
 #include "../../memstream.h"
 
 #if defined(_3DS)
@@ -41,6 +41,15 @@ static bool use_raw_palette;
 
 /* emulator-specific variables */
 
+/* overclock the console by adding dummy scanlines to PPU loop
+ * disables DMC DMA and WaveHi filling for these dummies
+ * doesn't work with new PPU */
+unsigned overclocked = 0;
+/* 7-bit samples have priority over overclocking */
+unsigned skip_7bit_overclocking = 1;
+unsigned normal_scanlines = 240;
+unsigned extrascanlines = 0;
+
 int FCEUnetplay;
 #ifdef PSP
 #include "pspgu.h"
@@ -52,9 +61,6 @@ static uint16_t* fceu_video_out;
 
 
 /* Some timing-related variables. */
-static int maxconbskip = 9;			/* Maximum consecutive blit skips. */
-static int ffbskip = 9;				/* Blit skips per blit when FF-ing */
-
 static int soundo = 1;
 
 static volatile int nofocus = 0;
@@ -467,8 +473,9 @@ void retro_set_controller_port_device(unsigned a, unsigned b)
 void retro_set_environment(retro_environment_t cb)
 {
    static const struct retro_variable vars[] = {
-      { "nes_palette", "Color Palette; asqrealc|loopy|quor|chris|matt|pasofami|crashman|mess|zaphod-cv|zaphod-smb|vs-drmar|vs-cv|vs-smb|nintendo-vc|raw" },
+      { "fceumm_palette", "Color Palette; asqrealc|loopy|quor|chris|matt|pasofami|crashman|mess|zaphod-cv|zaphod-smb|vs-drmar|vs-cv|vs-smb|nintendo-vc|raw" },
-      { "nes_nospritelimit", "No Sprite Limit; disabled|enabled" },
+      { "fceumm_nospritelimit", "No Sprite Limit; disabled|enabled" },
+      { "fceumm_overclocking", "Overclocking; disabled|2x" },
       { NULL, NULL },
    };
 
@@ -608,57 +615,91 @@ static const keymap bindmap[] = {
 
 static void check_variables(void)
 {
+   static int overclock_state = -1;
    struct retro_variable var = {0};
 
-   var.key = "nes_palette";
+   var.key = "fceumm_palette";
 
    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
    {
       unsigned orig_value = current_palette;
 
-      if (strcmp(var.value, "asqrealc") == 0)
+      if (!strcmp(var.value, "asqrealc"))
          current_palette = 0;
-      else if (strcmp(var.value, "loopy") == 0)
+      else if (!strcmp(var.value, "loopy"))
          current_palette = 1;
-      else if (strcmp(var.value, "quor") == 0)
+      else if (!strcmp(var.value, "quor"))
          current_palette = 2;
-      else if (strcmp(var.value, "chris") == 0)
+      else if (!strcmp(var.value, "chris"))
          current_palette = 3;
-      else if (strcmp(var.value, "matt") == 0)
+      else if (!strcmp(var.value, "matt"))
          current_palette = 4;
-      else if (strcmp(var.value, "matt") == 0)
+      else if (!strcmp(var.value, "matt"))
          current_palette = 5;
-      else if (strcmp(var.value, "pasofami") == 0)
+      else if (!strcmp(var.value, "pasofami"))
          current_palette = 6;
-      else if (strcmp(var.value, "crashman") == 0)
+      else if (!strcmp(var.value, "crashman"))
          current_palette = 7;
-      else if (strcmp(var.value, "mess") == 0)
+      else if (!strcmp(var.value, "mess"))
          current_palette = 8;
-      else if (strcmp(var.value, "zaphod-cv") == 0)
+      else if (!strcmp(var.value, "zaphod-cv"))
          current_palette = 9;
-      else if (strcmp(var.value, "zaphod-smb") == 0)
+      else if (!strcmp(var.value, "zaphod-smb"))
          current_palette = 10;
-      else if (strcmp(var.value, "vs-drmar") == 0)
+      else if (!strcmp(var.value, "vs-drmar"))
          current_palette = 11;
-      else if (strcmp(var.value, "vs-cv") == 0)
+      else if (!strcmp(var.value, "vs-cv"))
          current_palette = 12;
-      else if (strcmp(var.value, "vs-smb") == 0)
+      else if (!strcmp(var.value, "vs-smb"))
          current_palette = 13;
-      else if (strcmp(var.value, "nintendo-vc") == 0)
+      else if (!strcmp(var.value, "nintendo-vc"))
          current_palette = 14;
-      else if (strcmp(var.value, "raw") == 0)
+      else if (!strcmp(var.value, "raw"))
          current_palette = 15;
 
       if (current_palette != orig_value)
          retro_set_custom_palette();
    }
-   var.key = "nes_nospritelimit";
+
+   var.key = "fceumm_nospritelimit";
 
    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
    {
-      int no_sprite_limit = (strcmp(var.value, "enabled") == 0) ? 1 : 0;
+      int no_sprite_limit = (!strcmp(var.value, "enabled")) ? 1 : 0;
       FCEUI_DisableSpriteLimitation(no_sprite_limit);
    }
+
+   var.key = "fceumm_overclocking";
+
+   if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
+   {
+      bool do_reinit = false;
+
+      if (!strcmp(var.value, "disabled")
+            && overclock_state != 0)
+      {
+         overclocked            = 0;
+         skip_7bit_overclocking = 1;
+         extrascanlines         = 0;
+         overclock_state        = 0;
+         do_reinit              = true;
+      }
+      else if (!strcmp(var.value, "2x")
+            && overclock_state != 1)
+      {
+         overclocked            = 1;
+         skip_7bit_overclocking = 1;
+         extrascanlines         = 266;
+         overclock_state        = 1;
+         do_reinit              = true;
+      }
+
+      if (do_reinit)
+      {
+         FCEU_KillVirtualVideo();
+         FCEU_InitVirtualVideo();
+      }
+   }
 }
 
 /*

src/fceu.c

@@ -23,6 +23,7 @@
 #include  <stdlib.h>
 #include  <stdarg.h>
 
+#include "fceu.h"
 #include  "fceu-types.h"
 #include  "x6502.h"
 #include  "fceu.h"
@@ -48,6 +49,7 @@
 
 uint64 timestampbase;
 
+extern int totalscanlines;
 
 FCEUGI *GameInfo = NULL;
 void (*GameInterface)(int h);
@@ -460,6 +462,8 @@ void FCEU_ResetVidSys(void)
 
 	PAL = w ? 1 : 0;
 
+   totalscanlines = normal_scanlines + (overclocked ? extrascanlines : 0);
+
 	FCEUPPU_SetVideoSystem(w);
 	SetSoundVariables();
 }

src/fceu.h

@@ -4,6 +4,14 @@
 #include "fceu-types.h"
 
 extern int fceuindbg;
+
+extern unsigned overclocked;
+extern unsigned skip_7bit_overclocking;
+extern unsigned DMC_7bit;
+
+extern unsigned normal_scanlines;
+extern unsigned extrascanlines;
+
 void ResetGameLoaded(void);
 
 #define DECLFR(x) uint8 FP_FASTAPASS(1) x(uint32 A)

src/ppu.c

@@ -127,6 +127,8 @@ static int maxsprites = 8;
 int scanline;
 static uint32 scanlines_per_frame;
 
+int totalscanlines;
+
 uint8 PPU[4];
 uint8 PPUSPL;
 uint8 NTARAM[0x800], PALRAM[0x20], SPRAM[0x100], SPRBUF[0x100];
@@ -1180,7 +1182,7 @@ int FCEUPPU_Loop(int skip) {
 			kook ^= 1;
 		}
 		if (GameInfo->type == GIT_NSF)
-			X6502_Run((256 + 85) * 240);
+			X6502_Run((256 + 85) * normal_scanlines);
 		#ifdef FRAMESKIP
 		else if (skip) {
 			int y;
@@ -1209,11 +1211,20 @@ int FCEUPPU_Loop(int skip) {
 			int x, max, maxref;
 
 			deemp = PPU[1] >> 5;
-			for (scanline = 0; scanline < 240; ) {	//scanline is incremented in  DoLine.  Evil. :/
+
+         // manual samples can't play correctly with overclocking
+			if (DMC_7bit && skip_7bit_overclocking)
+				totalscanlines = normal_scanlines;
+			else
+				totalscanlines = normal_scanlines + (overclocked ? extrascanlines : 0);
+
+			for (scanline = 0; scanline < totalscanlines; ) {	//scanline is incremented in  DoLine.  Evil. :/
 				deempcnt[deemp]++;
 				if ((PPUViewer) && (scanline == PPUViewScanline)) UpdatePPUView(1);
 				DoLine();
 			}
+         DMC_7bit = 0;
+
 			if (MMC5Hack && (ScreenON || SpriteON)) MMC5_hb(scanline);
 			for (x = 1, max = 0, maxref = 0; x < 7; x++) {
 				if (deempcnt[x] > max) {

src/sound.c

@@ -61,6 +61,7 @@ typedef struct {
 	int reloaddec;
 } ENVUNIT;
 
+unsigned DMC_7bit = 0; // used to skip overclocking
 static ENVUNIT EnvUnits[3];
 
 static const int RectDuties[4] = { 1, 2, 4, 6 };
@@ -276,9 +277,19 @@ static DECLFW(Write_DMCRegs) {
 		break;
 	case 0x01: DoPCM();
 		RawDALatch = V & 0x7F;
+      if (RawDALatch)
+         DMC_7bit = 1;
 		break;
-	case 0x02: DMCAddressLatch = V; break;
+	case 0x02:
-	case 0x03: DMCSizeLatch = V; break;
+      DMCAddressLatch = V;
+      if (V)
+			DMC_7bit = 0;
+      break;
+	case 0x03:
+      DMCSizeLatch = V;
+      if (V)
+			DMC_7bit = 0;
+      break;
 	}
 }
 

src/video.c

@@ -48,7 +48,7 @@ int FCEU_InitVirtualVideo(void)
 {
    // 256 bytes per scanline, * 240 scanline maximum, +8 for alignment,
    if (!XBuf)
-      XBuf = (uint8*)(FCEU_malloc(256 * 256 + 8));
+      XBuf = (uint8*)(FCEU_malloc(256 * (256 + extrascanlines + 8)));
 
    if (!XBuf)
       return 0;
@@ -60,7 +60,7 @@ int FCEU_InitVirtualVideo(void)
       m = (4 - m) & 3;
       XBuf += m;
    }
-   memset(XBuf, 128, 256 * 256);
+   memset(XBuf, 128, 256 * (256 + extrascanlines));
    return 1;
 }
 

src/x6502.c

@@ -20,6 +20,7 @@
 
 #include <string.h>
 
+#include "fceu.h"
 #include "fceu-types.h"
 #include "x6502.h"
 #include "fceu.h"
@@ -51,7 +52,7 @@ void FP_FASTAPASS(1) (*MapIRQHook)(int a);
 	int __x = x;									\
 	_tcount += __x;									\
 	_count -= __x * 48;								\
-	timestamp += __x;								\
+   if (scanline < normal_scanlines || scanline == totalscanlines) timestamp+= __x; \
 }
 
 static INLINE uint8 RdMemNorm(uint32 A) {
@@ -509,7 +510,8 @@ static void X6502_RunDebug(int32 cycles) {
 		_tcount = 0;
 		if (MapIRQHook) MapIRQHook(temp);
 
-		FCEU_SoundCPUHook(temp);
+      if (scanline < normal_scanlines || scanline == totalscanlines)
+         FCEU_SoundCPUHook(temp);
 
 		_PC++;
 		switch (b1) {

src/x6502.h

@@ -23,6 +23,10 @@
 
 #include "x6502struct.h"
 
+extern int scanline;
+extern unsigned normal_scanlines;
+extern int totalscanlines;
+
 #ifdef FCEUDEF_DEBUGGER
 void X6502_Debug(void (*CPUHook)(X6502 *),
 				 uint8 (*ReadHook)(X6502 *, uint32),