From 6fb0c7a7a53e1eba7a0f5dc5b1ade312a0d76119 Mon Sep 17 00:00:00 2001
From: Toad King
Date: Thu, 14 Jun 2012 03:21:06 -0400
Subject: initial pocketsnes commit

---
 src/frame_skip.cpp | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 src/frame_skip.cpp

(limited to 'src/frame_skip.cpp')

diff --git a/src/frame_skip.cpp b/src/frame_skip.cpp
new file mode 100644
index 0000000..d656a0d
--- /dev/null
+++ b/src/frame_skip.cpp
@@ -0,0 +1,99 @@
+#include <unistd.h>
+#include <sys/time.h>
+#include <time.h>
+#include <math.h>
+#include "frame_skip.h"
+#include "memmap.h"
+
+#ifndef uclock_t
+#define uclock_t unsigned int
+#endif
+
+#define TICKS_PER_SEC 1000000UL
+//#define CPU_FPS 60
+static int CPU_FPS=60;
+static uclock_t F;
+
+#define MAX_FRAMESKIP 10
+
+
+static char init_frame_skip = 1;
+char skip_next_frame = 0;
+static struct timeval init_tv = { 0, 0 };
+
+
+void reset_frame_skip(void)
+{
+	//static Uint8 init=0;
+
+	init_tv.tv_usec = 0;
+	init_tv.tv_sec = 0;
+	skip_next_frame = 0;
+	init_frame_skip = 1;
+	CPU_FPS=Memory.ROMFramesPerSecond;
+
+	F = (uclock_t) ((double) TICKS_PER_SEC / CPU_FPS);
+}
+
+uclock_t get_ticks(void)
+{
+	struct timeval tv;
+
+	gettimeofday(&tv, 0);
+	if (init_tv.tv_sec == 0)
+		init_tv = tv;
+	return (tv.tv_sec - init_tv.tv_sec) * TICKS_PER_SEC + tv.tv_usec -
+		init_tv.tv_usec;
+
+
+}
+
+int frame_skip(void)
+{
+	static int f2skip;
+	static uclock_t sec = 0;
+	static uclock_t rfd;
+	static uclock_t target;
+	static int nbFrame = 0;
+	static int skpFrm = 0;
+
+	if (init_frame_skip) {
+		init_frame_skip = 0;
+		target = get_ticks();
+		nbFrame = 0;
+		//f2skip=0;
+		//skpFrm=0;
+		sec = 0;
+		return 0;
+	}
+
+	target += F;
+	if (f2skip > 0) {
+		f2skip--;
+		skpFrm++;
+		return 1;
+	} else
+		skpFrm = 0;
+
+
+	rfd = get_ticks();
+
+	if (rfd < target && f2skip == 0) {
+		while (get_ticks() < target);
+	} else {
+		f2skip = (rfd - target) / (double) F;
+		if (f2skip > MAX_FRAMESKIP) {
+			f2skip = MAX_FRAMESKIP;
+			reset_frame_skip();
+		}
+		// printf("Skip %d frame(s) %lu %lu\n",f2skip,target,rfd);
+	}
+	
+
+	nbFrame++;
+	if (get_ticks() - sec >= TICKS_PER_SEC) {
+		nbFrame = 0;
+		sec = get_ticks();
+	}
+	return 0;
+}
-- 
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