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Diffstat (limited to 'nuttx/sched/sched_addprioritized.c')
| -rw-r--r-- | nuttx/sched/sched_addprioritized.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/nuttx/sched/sched_addprioritized.c b/nuttx/sched/sched_addprioritized.c new file mode 100644 index 000000000..8f19a4731 --- /dev/null +++ b/nuttx/sched/sched_addprioritized.c @@ -0,0 +1,175 @@ +/************************************************************************ + * sched/sched_addprioritized.c + * + * Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ************************************************************************/ + +/************************************************************************ + * Included Files + ************************************************************************/ + +#include <nuttx/config.h> + +#include <stdint.h> +#include <stdbool.h> +#include <queue.h> +#include <assert.h> + +#include "os_internal.h" + +/************************************************************************ + * Pre-processor Definitions + ************************************************************************/ + +/************************************************************************ + * Private Type Declarations + ************************************************************************/ + +/************************************************************************ + * Global Variables + ************************************************************************/ + +/************************************************************************ + * Private Variables + ************************************************************************/ + +/************************************************************************ + * Private Function Prototypes + ************************************************************************/ + +/************************************************************************ + * Public Functions + ************************************************************************/ + +/************************************************************************ + * Name: sched_addprioritized + * + * Description: + * This function adds a TCB to a prioritized TCB list. + * + * Inputs: + * tcb - Points to the TCB to add to the prioritized list + * list - Points to the prioritized list to add tcb to + * + * Return Value: + * true if the head of the list has changed. + * + * Assumptions: + * - The caller has established a critical section before + * calling this function (calling sched_lock() first is NOT + * a good idea -- use irqsave()). + * - The caller has already removed the input tcb from + * whatever list it was in. + * - The caller handles the condition that occurs if the + * the head of the task list is changed. + * - The caller must set the task_state field of the TCB to + * match the state associated with the list. + ************************************************************************/ + +bool sched_addprioritized(FAR _TCB *tcb, DSEG dq_queue_t *list) +{ + FAR _TCB *next; + FAR _TCB *prev; + uint8_t sched_priority = tcb->sched_priority; + bool ret = false; + + /* Lets do a sanity check before we get started. */ + + ASSERT(sched_priority >= SCHED_PRIORITY_MIN); + + /* Search the list to find the location to insert the new Tcb. + * Each is list is maintained in ascending sched_priority order. + */ + + for (next = (FAR _TCB*)list->head; + (next && sched_priority <= next->sched_priority); + next = next->flink); + + /* Add the tcb to the spot found in the list. Check if the tcb + * goes at the end of the list. NOTE: This could only happen if list + * is the g_pendingtasks list! + */ + + if (!next) + { + /* The tcb goes at the end of the list. */ + + prev = (FAR _TCB*)list->tail; + if (!prev) + { + /* Special case: The list is empty */ + + tcb->flink = NULL; + tcb->blink = NULL; + list->head = (FAR dq_entry_t*)tcb; + list->tail = (FAR dq_entry_t*)tcb; + ret = true; + } + else + { + /* The tcb goes at the end of a non-empty list */ + + tcb->flink = NULL; + tcb->blink = prev; + prev->flink = tcb; + list->tail = (FAR dq_entry_t*)tcb; + } + } + else + { + /* The tcb goes just before next */ + + prev = (FAR _TCB*)next->blink; + if (!prev) + { + /* Special case: Insert at the head of the list */ + + tcb->flink = next; + tcb->blink = NULL; + next->blink = tcb; + list->head = (FAR dq_entry_t*)tcb; + ret = true; + } + else + { + /* Insert in the middle of the list */ + + tcb->flink = next; + tcb->blink = prev; + prev->flink = tcb; + next->blink = tcb; + } + } + + return ret; +} + |