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/*******************************************************************************
* Copyright (C) 2018 Cadence Design Systems, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to use this Software with Cadence processor cores only and
* not with any other processors and platforms, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
******************************************************************************/
/*******************************************************************************
* xf-sched.c
*
* Non-preemptive earliest-deadline-first scheduler
*
******************************************************************************/
#define MODULE_TAG SCHED
/*******************************************************************************
* Includes
******************************************************************************/
#include "xf.h"
/*******************************************************************************
* Tracing configuration
******************************************************************************/
TRACE_TAG(DEBUG, 1);
/*******************************************************************************
* Global functions definitions
******************************************************************************/
/* ...place task into scheduler queue */
void xf_sched_put(xf_sched_t *sched, xf_task_t *t, u32 ts)
{
rb_tree_t *tree = (rb_tree_t *)sched;
rb_node_t *node = (rb_node_t *)t;
rb_idx_t p_idx, t_idx;
u32 _ts;
/* ...set scheduling timestamp */
xf_task_timestamp_set(t, ts);
/* ...find a place in the tree where the message should be inserted */
for (p_idx = rb_root(tree); p_idx != rb_null(tree); p_idx = t_idx)
{
/* ...get timestamp of the p_idx */
_ts = xf_task_timestamp((xf_task_t *)p_idx);
/* ...ordering respects FIFO order of messages with same timestamp */
if (xf_timestamp_before(ts, _ts))
{
if ((t_idx = rb_left(tree, p_idx)) == rb_null(tree))
{
/* ...p_idx is a direct successor of the message */
rb_set_left(tree, p_idx, node);
/* ...adjust head of the tree if needed */
if (p_idx == rb_cache(tree)) goto insert_head;
else goto insert;
}
}
else
{
if ((t_idx = rb_right(tree, p_idx)) == rb_null(tree))
{
/* ...p_idx is a direct predeccessor of the message */
rb_set_right(tree, p_idx, node);
goto insert;
}
}
}
insert_head:
/* ...adjust scheduler head element */
rb_set_cache(tree, node);
insert:
/* ...insert item and rebalance the tree */
rb_insert(tree, node, p_idx);
/* ...head cannot be NULL */
BUG(rb_cache(tree) == rb_null(tree), _x("Invalid scheduler state"));
TRACE(DEBUG, _b("in: %x:[%p] (ts:%x)"), ts, node, xf_sched_timestamp(sched));
}
/* ...get first item from the scheduler */
xf_task_t * xf_sched_get(xf_sched_t *sched)
{
rb_tree_t *tree = (rb_tree_t *)sched;
rb_idx_t n_idx, t_idx;
u32 ts;
/* ...head of the tree is cached; replace it with its parent (direct successor) */
if ((n_idx = rb_cache(tree)) == rb_null(tree))
{
/* ...tree is empty; bail out */
return NULL;
}
else
{
/* ...delete current node and rebalance the tree */
t_idx = rb_delete(tree, n_idx), rb_set_cache(tree, t_idx);
/* ...get task timestamp */
ts = xf_task_timestamp((xf_task_t *)n_idx);
/* ...advance scheduler timestamp */
xf_sched_timestamp_set(sched, ts);
TRACE(DEBUG, _b("out: %x:[%p]"), ts, n_idx);
/* ...return task */
return (xf_task_t *)n_idx;
}
}
/* ...cancel specified task execution (must be scheduled!) */
void xf_sched_cancel(xf_sched_t *sched, xf_task_t *t)
{
rb_tree_t *tree = (rb_tree_t *)sched;
rb_idx_t n_idx = t;
rb_idx_t t_idx;
/* ...delete message from tree */
t_idx = rb_delete(tree, n_idx);
/* ...adjust head if that was the first message */
(n_idx == rb_cache(tree) ? rb_set_cache(tree, t_idx), 1 : 0);
}
/* ...initialize scheduler data */
void xf_sched_init(xf_sched_t *sched)
{
rb_init((rb_tree_t *)sched);
}
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