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/************************************************************************/
/* */
/* File: core.c */
/* Description: kernel entry point */
/* Version: 1.0 */
/* Author: Otto Mattik */
/* */
/* (C)Copyright Otto Mattik 2014-2021. */
/* */
/* This file is a part of 'armen' (a tiny operating system). */
/* 'armen' is distributed under the CeCILL-V2.1 licence. For more */
/* details about this licence, please visit the website cecill.info */
/* */
/************************************************************************/
#include "core.h"
static uint32_t _time;
extern void* main( void* );
/*
* called from armen_start (see assembly code)
*
* input:
* ram_start beginning of free ram
* ram_end end of ram
* output:
*/
void _sys_init( void* ram_start, void* ram_end )
{
register uint8_t i;
register uint16_t stack_per_thread;
register void* stack;
/*
* initialize stacks in table of threads
*/
stack_per_thread = (ram_end - ram_start - IDLE_STACK_SIZE) / (ARMEN_THREADS - 1);
stack = ram_end;
for( i = 1; i < ARMEN_THREADS; i++ )
{
_threads[i].istack = stack;
stack -= stack_per_thread;
}
/*
* thread0 = idle
*/
_threads[0].istack = stack;
_threads[0].cstack = _init_context( _idle, 0, stack );
_threads[0].rank =
_threads[0].order = 255;
_threads[0].entry = _idle;
_threads[0].status = TS_RUNNING;
/*
* thread1 = main
*/
_threads[1].cstack = _threads[1].istack;
_threads[1].rank = 127;
_threads[1].entry = main;
_threads[1].status = TS_RUNNING;
_cur_thread = 1;
#if defined(UART) && (UART != 0)
_uart_init( );
#endif
}
/*
* called by timer every millisecond (see assembly code)
*
* input:
* output:
*/
void _sys_clock( void )
{
register uint8_t i;
register _thread_t* pthread;
++_time;
/*
* update priorities
*/
for( i = 1; i < ARMEN_THREADS; i++ )
{
pthread = &_threads[i];
if( pthread->status == TS_UNUSED )
continue;
if( pthread->status == TS_RUNNING )
{
if( i == _cur_thread )
{
if( pthread->order != 254 )
++pthread->order;
}
else
{
if( pthread->order != 0 )
--pthread->order;
}
}
/*
* update thread timer(s)
*/
else
{
if( pthread->timer1 != 0 && --pthread->timer1 == 0
&& (pthread->events & EVENT_TIMER1) != 0
)
{
pthread->events &= ~EVENT_TIMER1;
pthread->event |= EVENT_TIMER1;
pthread->order = 0;
pthread->status = TS_RUNNING;
}
#if (ARMEN_TIMERS == 2)
if( pthread->timer2 != 0 && --pthread->timer2 == 0
&& (pthread->events & EVENT_TIMER2) != 0
)
{
pthread->events &= ~EVENT_TIMER2;
pthread->event |= EVENT_TIMER2;
pthread->order = 0;
pthread->status = TS_RUNNING;
}
#endif
}
}
}
/*
* thread election
*
* input:
* sp current value of stack pointer
* output:
*/
void _scheduler( void* sp )
{
register uint8_t i, rank, order, elected;
register _thread_t* pthread;
elected = 0;
rank = order = 255;
_threads[_cur_thread].cstack = sp;
for( i = 1; i < ARMEN_THREADS; i++ )
{
pthread = &_threads[i];
if( pthread->status != TS_RUNNING
|| pthread->order > order
|| (pthread->order == order && pthread->rank > rank ) )
continue;
elected = i;
rank = pthread->rank;
order = pthread->order;
}
if( elected != _cur_thread )
{
_cur_thread = elected;
_restore_context( _threads[elected].cstack );
/* no return */
}
}
/*
* get current time (milliseconds since start-up)
*
* input:
* output:
* count of milliseconds
*/
uint32_t get_time( void )
{
return( _time );
}
/*
* suspend execution of the calling thread
*
* input:
* events mask of events
* output:
* event occured
*/
uint16_t wait_event( uint16_t events )
{
uint16_t ret = 0;
if( events != 0 )
{
do
{
_disable_intr( );
_threads[_cur_thread].events |= events;
_threads[_cur_thread].status = TS_SUSPENDED;
_schedule( );
}
while( (_threads[_cur_thread].event & events) == 0 ) ;
ret = _threads[_cur_thread].event & events;
_threads[_cur_thread].event &= ~events;
}
return( ret );
}
/*
* current value of timer
*
* input:
* timer timer identifier
* output:
* timer value if success, otherwise -1
*/
timer_t get_timer( uint8_t timer )
{
#ifdef CHECK_PARAM
if( timer < 1 || timer > ARMEN_TIMERS )
return( (timer_t)-1 );
#endif
#if (ARMEN_TIMERS == 2)
if( timer == 2 )
return( _threads[_cur_thread].timer2 );
#endif
return( _threads[_cur_thread].timer1 );
}
/*
* suspend current thread during a period
*
* input:
* timer timer identifier
* msecs period in milliseconds
* output:
* 0 if success, otherwise -1
*/
int8_t set_timer( uint8_t timer, timer_t msecs )
{
#ifdef CHECK_PARAM
if( timer < 1 || timer > ARMEN_TIMERS )
return( -1 );
#endif
#if (ARMEN_TIMERS == 2)
if( timer == 2 )
{
_threads[_cur_thread].timer2 = msecs;
if( msecs != 0 )
_threads[_cur_thread].events &= ~EVENT_TIMER2;
else
_threads[_cur_thread].events |= EVENT_TIMER2;
}
else
#endif
{
_threads[_cur_thread].timer1 = msecs;
if( msecs != 0 )
_threads[_cur_thread].events &= ~EVENT_TIMER1;
else
_threads[_cur_thread].events |= EVENT_TIMER1;
}
return( 0 );
}
void sleep( timer_t msecs )
{
if( msecs != 0 )
{
_threads[_cur_thread].events |= EVENT_TIMER1;
_threads[_cur_thread].timer1 = msecs;
wait_event( EVENT_TIMER1 );
}
}
/*
* wake up thread(s) on event
*
* input:
* event reason for wake up
* param depends on event
* output:
*/
void _wakeup( uint16_t event, void* param )
{
register uint8_t i;
register _thread_t* pthread;
for( i = 1; i < ARMEN_THREADS; i++ )
{
pthread = &_threads[i];
if( pthread->status != TS_SUSPENDED
|| (pthread->events & event) == 0
#if defined(USE_SEM)
|| (event == EVENT_SEM && pthread->sem != param)
#endif
|| (event == EVENT_JOIN && pthread->joinid != _cur_thread) )
continue;
if( event == EVENT_JOIN )
pthread->param = param;
pthread->events &= ~event;
pthread->event |= event;
pthread->order = 0;
pthread->status = TS_RUNNING;
}
}
void send_user_event( void )
{
register uint8_t iflag;
iflag = _disable_intr( );
_wakeup( EVENT_USER, 0 );
_enable_intr( iflag );
}
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