1 files changed, 168 insertions, 0 deletions

diff --git a/uisimulator/sdl/kernel-sdl.c b/uisimulator/sdl/kernel-sdl.c
new file mode 100644
index 0000000000..b6e6a34551
--- /dev/null
+++ b/uisimulator/sdl/kernel-sdl.c
@@ -0,0 +1,168 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2002 by Felix Arends
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include <stdlib.h>
+#include <SDL.h>
+#include <SDL_thread.h>
+#include "memory.h"
+#include "system-sdl.h"
+#include "uisdl.h"
+#include "kernel.h"
+#include "thread-sdl.h"
+#include "thread.h"
+#include "debug.h"
+
+static SDL_TimerID tick_timer_id;
+long start_tick;
+
+/* Condition to signal that "interrupts" may proceed */
+static SDL_cond *sim_thread_cond;
+/* Mutex to serialize changing levels and exclude other threads while
+ * inside a handler */
+static SDL_mutex *sim_irq_mtx;
+static int interrupt_level = HIGHEST_IRQ_LEVEL;
+static int handlers_pending = 0;
+static int status_reg = 0;
+
+extern void (*tick_funcs[MAX_NUM_TICK_TASKS])(void);
+
+/* Nescessary logic:
+ * 1) All threads must pass unblocked
+ * 2) Current handler must always pass unblocked
+ * 3) Threads must be excluded when irq routine is running
+ * 4) No more than one handler routine should execute at a time
+ */
+int set_irq_level(int level)
+{
+    SDL_LockMutex(sim_irq_mtx);
+
+    int oldlevel = interrupt_level;
+
+    if (status_reg == 0 && level == 0 && oldlevel != 0)
+    {
+        /* Not in a handler and "interrupts" are being reenabled */
+        if (handlers_pending > 0)
+            SDL_CondSignal(sim_thread_cond);
+    }
+
+    interrupt_level = level; /* save new level */
+
+    SDL_UnlockMutex(sim_irq_mtx);
+    return oldlevel;
+}
+
+void sim_enter_irq_handler(void)
+{
+    SDL_LockMutex(sim_irq_mtx);
+    handlers_pending++;
+
+    if(interrupt_level != 0)
+    {
+        /* "Interrupts" are disabled. Wait for reenable */
+        SDL_CondWait(sim_thread_cond, sim_irq_mtx);
+    }
+
+    status_reg = 1;
+}
+
+void sim_exit_irq_handler(void)
+{
+    if (--handlers_pending > 0)
+        SDL_CondSignal(sim_thread_cond);
+
+    status_reg = 0;
+    SDL_UnlockMutex(sim_irq_mtx);
+}
+
+bool sim_kernel_init(void)
+{
+    sim_irq_mtx = SDL_CreateMutex();
+    if (sim_irq_mtx == NULL)
+    {
+        fprintf(stderr, "Cannot create sim_handler_mtx\n");
+        return false;
+    }
+
+    sim_thread_cond = SDL_CreateCond();
+    if (sim_thread_cond == NULL)
+    {
+        fprintf(stderr, "Cannot create sim_thread_cond\n");
+        return false;
+    }
+
+    return true;
+}
+
+void sim_kernel_shutdown(void)
+{
+    SDL_RemoveTimer(tick_timer_id);
+    SDL_DestroyMutex(sim_irq_mtx);
+    SDL_DestroyCond(sim_thread_cond);
+}
+
+Uint32 tick_timer(Uint32 interval, void *param)
+{
+    long new_tick;
+
+    (void) interval;
+    (void) param;
+    
+    new_tick = (SDL_GetTicks() - start_tick) / (1000/HZ);
+        
+    if(new_tick != current_tick)
+    {
+        long t;
+        for(t = new_tick - current_tick; t > 0; t--)
+        {
+            int i;
+
+            sim_enter_irq_handler();
+
+            /* Run through the list of tick tasks */
+            for(i = 0;i < MAX_NUM_TICK_TASKS;i++)
+            {
+                if(tick_funcs[i])
+                {
+                    tick_funcs[i]();
+                }
+            }
+
+            sim_exit_irq_handler();
+        }
+
+        current_tick = new_tick;
+    }
+    
+    return 1;
+}
+
+void tick_start(unsigned int interval_in_ms)
+{
+    if (tick_timer_id != NULL)
+    {
+        SDL_RemoveTimer(tick_timer_id);
+        tick_timer_id = NULL;
+    }
+    else
+    {
+        start_tick = SDL_GetTicks();
+    }
+
+    tick_timer_id = SDL_AddTimer(interval_in_ms, tick_timer, NULL);
+}