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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2002 by Felix Arends
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* 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;
/* 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);
while(new_tick != current_tick)
{
sim_enter_irq_handler();
/* Run through the list of tick tasks - increments tick
* on each iteration. */
call_tick_tasks();
sim_exit_irq_handler();
}
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);
}
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