From 18c3f5f698bd675f007e9cc1dc41a84487bc4497 Mon Sep 17 00:00:00 2001
From: Aaron Culliney <devnull@deadc0de.org>
Date: Tue, 2 Jul 2013 01:10:57 -0700
Subject: [PATCH] we no longer use timers with setitimer and SIGVTALRM, that's
 so nineties...

instead spin off a cpu_thread and have it ping the main render thread as needed
---
 src/keys.c   |  2 --
 src/keys.h   |  2 --
 src/misc.c   | 54 ++++++++++++++++++++++++++++++----------------------
 src/misc.h   |  2 --
 src/timing.c | 22 +++++++++++++++++++--
 5 files changed, 51 insertions(+), 31 deletions(-)

diff --git a/src/keys.c b/src/keys.c
index aae40533..e6c662fa 100644
--- a/src/keys.c
+++ b/src/keys.c
@@ -352,9 +352,7 @@ void c_periodic_update(int dummysig) {
  */
 void enter_debugger(void)
 {
-     setitimer(ITIMER_VIRTUAL,&timer_off,0);
      c_do_debugging();
-     setitimer(ITIMER_VIRTUAL,&timer_on,0);
 }
 
 /* -------------------------------------------------------------------------
diff --git a/src/keys.h b/src/keys.h
index aea89c41..f6988b22 100644
--- a/src/keys.h
+++ b/src/keys.h
@@ -73,8 +73,6 @@
 #define kPGDN	164
 #define kEND 	165
 
-#define	 TIMER_DELAY		30000L
-
 
 #ifdef PC_JOYSTICK
 extern int js_fd;
diff --git a/src/misc.c b/src/misc.c
index 9f87974e..b155950e 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -19,6 +19,8 @@
 #include <ctype.h>
 #include <stdlib.h>
 #include <signal.h>
+#include <time.h>
+#include <pthread.h>
 #include <sys/ioctl.h>
 #include <sys/time.h>
 #include <sys/io.h>
@@ -32,9 +34,7 @@
 #include "cpu.h"
 #include "glue.h"
 #include "prefs.h"
-
-const struct itimerval timer_off = {{0,0},{0,0}};
-const struct itimerval timer_on = {{0,TIMER_DELAY},{0,TIMER_DELAY}};
+#include "timing.h"
 
 /* ----------------------------------
     internal apple2 variables
@@ -45,6 +45,9 @@ static unsigned char	apple_ii_rom[12288];
 static unsigned char	apple_iie_rom[32768];		/* //e */
 #endif
 
+pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
+
 /* in debugger.c */
 extern int breakpoints[];
 extern int watchpoints[];
@@ -704,10 +707,6 @@ static void c_initialize_firsttime()
     /* initialize the video system */
     video_init();
 
-    /* Enable periodic updates */
-    signal(SIGVTALRM,c_periodic_update);
-    setitimer(ITIMER_VIRTUAL,&timer_on,0); 
-
     reinitialize();     
 }
 
@@ -715,29 +714,38 @@ void c_read_random() {
     random_value = (unsigned char)(rand() >> 8);
 }
 
+static void cpu_thread (void *dummyptr) {
+
+    do {
+        cpu65_run();
+	reinitialize();
+    } while (1);
+}
+
+static void main_thread (void *dummyptr) {
+    do {
+        // sleep waiting for the cpu thread to ping us that it's sleeping...
+        pthread_mutex_lock(&mutex);
+        pthread_cond_wait(&cond, &mutex);
+        pthread_mutex_unlock(&mutex);
+
+        c_periodic_update(0);
+    } while (1);
+}
+
 int main(int sargc, char *sargv[])
 {
-    int		i;
-
     argc = sargc;
     argv = sargv;
 
-    for (i = 1; i < argc; i++)
-    {
-/*
-	if (strcmp(argv[i], "-vga") == 0)
-	    force_vga_mode = 1;
-*/
-    }
-
     load_settings();			/* user prefs */
     c_initialize_firsttime();		/* init svga graphics and vm */
+    timing_initialize();
 
-    for (;;) {
-	/* execute the emulator */
-        cpu65_run();
+    // spin off cpu thread
+    pthread_t thread1;
+    pthread_create(&thread1, NULL, (void *) &cpu_thread, (void *)NULL);
 
-	reinitialize();
-    }
-    /* never reached */
+    // enter main render thread
+    main_thread(NULL);
 }
diff --git a/src/misc.h b/src/misc.h
index 37057f58..4517cb6b 100644
--- a/src/misc.h
+++ b/src/misc.h
@@ -39,8 +39,6 @@
 #define SW_IOUDIS 0xC07E
 #endif
 
-extern const struct itimerval timer_on,timer_off;
-
 /* Text characters */
 extern const unsigned char ucase_glyphs[0x200];
 extern const unsigned char lcase_glyphs[0x100];
diff --git a/src/timing.c b/src/timing.c
index 9b1cfe4c..e28e5389 100644
--- a/src/timing.c
+++ b/src/timing.c
@@ -15,8 +15,9 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <time.h>
+#include <pthread.h>
 
-#define DEFAULT_SLEEP 60
+#define DEFAULT_SLEEP 120
 
 static unsigned int sleep_hz             = DEFAULT_SLEEP;               // sleep intervals per sec
 static unsigned long cpu_target_hz       = APPLE2_HZ;                   // target clock speed
@@ -28,6 +29,9 @@ static unsigned long cycle=0;
 static long sleep_adjust=0;
 static long sleep_adjust_inc=0;
 
+extern pthread_mutex_t mutex;
+extern pthread_cond_t cond;
+
 // -----------------------------------------------------------------------------
 
 // assuming end > start, returns end - start
@@ -66,16 +70,30 @@ void timing_set_sleep_hz (unsigned int hz) {
 /*
  * Throttles the 65c02 CPU down to a target frequency of X.
  * Currently set to target the Apple //e @ 1.02MHz
+ *
+ * This is called from cpu65_run() on the cpu-thread
  */
 void timing_throttle () {
     ++cycle;
 
+    static time_t severe_lag=0;
+
     if ((cycle%cycles_interval) == 0) {
+
+        // wake render thread as we go to sleep
+        pthread_mutex_lock(&mutex);
+        pthread_cond_signal(&cond);
+        pthread_mutex_unlock(&mutex);
+
         clock_gettime(CLOCK_MONOTONIC, &tj);
         deltat = timespec_diff(ti, tj);
         ti=tj;
         if (deltat.tv_sec != 0) {
-            // severely lagging ...
+            // severely lagging, don't bother sleeping ...
+            if (severe_lag < time(NULL)) {
+                severe_lag = time(NULL)+2;
+                fprintf(stderr, "Severe lag detected...\n");
+            }
         } else {
             deltat.tv_nsec = processing_interval - deltat.tv_nsec + sleep_adjust_inc;
             nanosleep(&deltat, NULL); // NOTE: spec says will return right away if deltat.tv_nsec value < 0 ...