Add Free Running Timer implementation

Doesn't work in Fusion, only useful for profiling.

Major thanks to Chilly Willy

32x.h

@@ -116,7 +116,15 @@
 
 #define SH2_DMA_DMAOR       (*(volatile unsigned long *)0xFFFFFFB0)
 
+#define SH2_INT_ICR         (*(volatile unsigned short *)0xFFFFFEE0)
 #define SH2_INT_IPRA        (*(volatile unsigned short *)0xFFFFFEE2)
+#define SH2_INT_IPRB        (*(volatile unsigned short *)0xFFFFFE60)
+#define SH2_INT_VCRA        (*(volatile unsigned short *)0xFFFFFE62)
+#define SH2_INT_VCRB        (*(volatile unsigned short *)0xFFFFFE64)
+#define SH2_INT_VCRC        (*(volatile unsigned short *)0xFFFFFE66)
+#define SH2_INT_VCRD        (*(volatile unsigned short *)0xFFFFFE68)
+#define SH2_INT_VCRWDT      (*(volatile unsigned short *)0xFFFFFEE4)
+#define SH2_INT_VCRDIV      (*(volatile unsigned long *)0xFFFFFF0C)
 
 #define SEGA_CTRL_UP        0x0001
 #define SEGA_CTRL_DOWN      0x0002

crt0.s

@@ -255,6 +255,7 @@ master_vbr:
         .long   master_hbi      /* H Blank interupt */
         .long   master_vbi      /* V Blank interupt */
         .long   master_rst      /* Reset Button */
+        .long   master_frt      /* FRT overflow */
 
 !-----------------------------------------------------------------------
 ! Slave Vector Base Table
@@ -440,6 +441,39 @@ master_lvl4_5:
         rte
         nop
 
+!-----------------------------------------------------------------------
+! Master FRT Overflow IRQ handler
+!-----------------------------------------------------------------------
+
+master_frt:
+        mov.l   r0,@-r15
+        mov.l   r1,@-r15
+
+        mov.l   sh2_frt_ftcsr,r1
+        mov.b	@r1,r0
+        tst     #2,r0
+        bt      9f
+        /* overflow */
+        mov     #0,r0
+        mov.w   r0,@r1  /* clear OVF IRQ */
+
+        mov.l   frt_ovf_count_ptr,r1
+        mov.l   @r1,r0
+        add     #1,r0
+        mov.l   r0,@r1
+9:
+        mov.l   @r15+,r1
+        mov.l   @r15+,r0
+        rte
+        nop
+
+        .align  2
+sh2_frt_ftcsr:
+        .long   0xFFFFFE11
+
+frt_ovf_count_ptr:
+        .long   _frt_ovf_count
+
 !-----------------------------------------------------------------------
 ! Master V Blank IRQ handler
 !-----------------------------------------------------------------------

doomdef.h

@@ -678,6 +678,7 @@ unsigned I_NetTransfer (unsigned buttons);
 boolean	I_RefreshCompleted (void) ATTR_DATA_CACHE_ALIGN;
 boolean	I_RefreshLatched (void);
 int	I_GetTime (void) ATTR_DATA_CACHE_ALIGN;
+int     I_GetFRTCounter (void) ATTR_DATA_CACHE_ALIGN;
 
 void I_Update (void);
 

marsnew.c

@@ -39,7 +39,12 @@ const int COLOR_WHITE = 0x04;
 int		activescreen = 0;
 short	*dc_colormaps;
 
-int		vblank_count = 0;
+unsigned	vblank_count = 0;
+unsigned	frt_ovf_count = 0;
+static float frt_counter2msec = 0;
+
+const int NTSC_CLOCK_SPEED = 23011360; // HZ
+const int PAL_CLOCK_SPEED  = 22801467; // HZ
 
 extern int 	debugmode;
 
@@ -81,10 +86,26 @@ void Mars_Init(void)
 	int i, j;
 	volatile unsigned short *lines = &MARS_FRAMEBUFFER;
 	volatile unsigned short *palette;
+	boolean NTSC;
 
 	while ((MARS_SYS_INTMSK & MARS_SH2_ACCESS_VDP) == 0);
 
 	MARS_VDP_DISPMODE = MARS_224_LINES | MARS_VDP_MODE_256;
+	NTSC = (MARS_VDP_DISPMODE & MARS_NTSC_FORMAT) != 0;
+
+	/* init hires timer system */
+	SH2_FRT_TCR = 2;									/* TCR set to count at SYSCLK/128 */
+	SH2_FRT_FRCH = 0;
+	SH2_FRT_FRCL = 0;
+	SH2_INT_IPRB = (SH2_INT_IPRB & 0xF0FF) | 0x0E00; 	/* set FRT INT to priority 14 */
+	SH2_INT_VCRD = 72 << 8; 							/* set exception vector for FRT overflow */
+	SH2_FRT_FTCSR = 0;									/* clear any int status */
+	SH2_FRT_TIER = 3;									/* enable overflow interrupt */
+
+	MARS_SYS_COMM4 = 0;
+
+	// change 128.0f to something else if SH2_FRT_TCR is changed!
+	frt_counter2msec = 128.0f * 1000.0f / (NTSC ? NTSC_CLOCK_SPEED : PAL_CLOCK_SPEED);
 
 	activescreen = MARS_VDP_FBCTL;
 
@@ -101,15 +122,13 @@ void Mars_Init(void)
 		Mars_FlipFrameBuffers(true);
 	}
 
-	ticrate = (MARS_VDP_DISPMODE & MARS_NTSC_FORMAT) ? 4 : 3;
+	ticrate = NTSC ? 4 : 3;
 
 	/* set a two color palette */
 	palette = &MARS_CRAM;
 	for (i = 0; i < 256; i++)
 		palette[i] = 0;
 	palette[COLOR_WHITE] = 0x7fff;
-
-	MARS_SYS_COMM4 = 0;
 }
 
 int Mars_ToDoomControls(int ctrl)
@@ -312,6 +331,17 @@ int	I_GetTime (void)
 	return *(int *)((intptr_t)&vblank_count | 0x20000000);
 }
 
+int I_GetFRTCounter(void)
+{
+	unsigned cnt = (SH2_FRT_FRCH << 8) | SH2_FRT_FRCL;
+	return (int)((frt_ovf_count << 16) | cnt);
+}
+
+int I_FRTCounter2Msec(int c)
+{
+	return (int)((float)c * frt_counter2msec);
+}
+
 /*
 ====================
 =

marsonly.c

@@ -28,6 +28,7 @@ void Mars_Init(void);
 void Mars_Slave(void);
 
 void I_ClearWorkBuffer();
+int I_FRTCounter2Msec(int c);
 
 /* 
 ================