Nyaaori/rockbox
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Made set_irq_level() and queue_post() interrupt safe

Browse source 
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@521 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Linus Nielsen Feltzing 2002-05-08 22:07:41 +00:00
parent bd262a5dbe
commit b7104fcd48
1 changed files with 18 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

29
firmware/kernel.c
View file

@ -52,20 +52,22 @@ void yield(void)
/****************************************************************************
* Interrupt level setting
* NOTE!!!!!!
* This one is not entirely safe. If an interrupt uses this function it
* MUST restore the old level before returning. Otherwise there is a small
* risk that set_irq_level returns the wrong level if interrupted after
* the stc instruction.
****************************************************************************/
static int current_irq_level = 15;
int set_irq_level(int level)
{
int i;
int old;
/* Read the old level and set the new one */
asm volatile ("stc sr, %0" : "=r" (i));
asm volatile ("ldc %0, sr" : : "r" (level<<4));
return (i >> 4) & 0x0f;
/* First raise to highest level and update the shadow */
asm volatile ("ldc %0, sr" : : "r" (15<<4));
old = current_irq_level;
current_irq_level = level;
/* Then set the wanted level */
asm volatile ("ldc %0, sr" : : "r" ((unsigned int)level<<4));
return ((unsigned int)old >> 4) & 0x0f;
}
/****************************************************************************
@ -89,10 +91,15 @@ struct event *queue_wait(struct event_queue *q)
void queue_post(struct event_queue *q, int id, void *data)
{
int wr = (q->write++) & QUEUE_LENGTH_MASK;
int wr;
int oldlevel;
oldlevel = set_irq_level(15);
wr = (q->write++) & QUEUE_LENGTH_MASK;
q->events[wr].id = id;
q->events[wr].data = data;
set_irq_level(oldlevel);
}