KERNEL DESIGN ISSUES - Hard Real-Time Computing Systems: Predictable Scheduling Algorithms and Applications - page 390

/*-----------------------------------------------------------*/
/* reserve -- reserves a buffer in a CAB */
/*-----------------------------------------------------------*/
pointer reserve (cab c)
pointer p;
<disable cpu interrupts>
p = c.free;

/* get a free buffer */

c.free = p.next; /* update the free list */

return(p);
<enable cpu interrupts>

}

/*-----------------------------------------------------------*/
/* putmes -- puts a message in a CAB */
/*-----------------------------------------------------------*/
void

putmes (cab c, pointer p)

{

<disable cpu interrupts>
if (c.mrb.use == 0)

{

/* if not accessed, */

c.mrb.next = c.free; /* deallocate the mrb */

c.free = c.mrb;
c.mrb = p;

/* update the mrb */

<enable cpu interrupts>

}