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Diffstat (limited to 'nuttx/sched/sched_mergepending.c')
| -rw-r--r-- | nuttx/sched/sched_mergepending.c | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/nuttx/sched/sched_mergepending.c b/nuttx/sched/sched_mergepending.c new file mode 100644 index 000000000..71d575c23 --- /dev/null +++ b/nuttx/sched/sched_mergepending.c @@ -0,0 +1,177 @@ +/************************************************************************ + * sched/sched_mergepending.c + * + * Copyright (C) 2007, 2009, 2012 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 <stdbool.h> +#include <sched.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_mergepending + * + * Description: + * This function merges the prioritized g_pendingtasks list into the + * prioritized g_readytorun task list. + * + * Inputs: + * None + * + * Return Value: + * true if the head of the g_readytorun task 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 handles the condition that occurs if the + * the head of the sched_mergTSTATE_TASK_PENDINGs is changed. + * + ************************************************************************/ + +bool sched_mergepending(void) +{ + FAR _TCB *pndtcb; + FAR _TCB *pndnext; + FAR _TCB *rtrtcb; + FAR _TCB *rtrprev; + bool ret = false; + + /* Initialize the inner search loop */ + + rtrtcb = (FAR _TCB*)g_readytorun.head; + + /* Process every TCB in the g_pendingtasks list */ + + for (pndtcb = (FAR _TCB*)g_pendingtasks.head; pndtcb; pndtcb = pndnext) + { + pndnext = pndtcb->flink; + + /* Search the g_readytorun list to find the location to insert the + * new pndtcb. Each is list is maintained in ascending sched_priority + * order. + */ + + for (; + (rtrtcb && pndtcb->sched_priority <= rtrtcb->sched_priority); + rtrtcb = rtrtcb->flink); + + /* Add the pndtcb to the spot found in the list. Check if the + * pndtcb goes at the ends of the g_readytorun list. This would be + * error condition since the idle test must always be at the end of + * the g_readytorun list! + */ + + if (!rtrtcb) + { + PANIC(OSERR_NOIDLETASK); + } + else + { + /* The pndtcb goes just before rtrtcb */ + + rtrprev = rtrtcb->blink; + if (!rtrprev) + { + /* Special case: Inserting pndtcb at the head of the list */ + /* Inform the instrumentation layer that we are switching tasks */ + + sched_note_switch(rtrtcb, pndtcb); + + /* Then insert at the head of the list */ + + pndtcb->flink = rtrtcb; + pndtcb->blink = NULL; + rtrtcb->blink = pndtcb; + g_readytorun.head = (FAR dq_entry_t*)pndtcb; + rtrtcb->task_state = TSTATE_TASK_READYTORUN; + pndtcb->task_state = TSTATE_TASK_RUNNING; + ret = true; + } + else + { + /* Insert in the middle of the list */ + + pndtcb->flink = rtrtcb; + pndtcb->blink = rtrprev; + rtrprev->flink = pndtcb; + rtrtcb->blink = pndtcb; + pndtcb->task_state = TSTATE_TASK_READYTORUN; + } + } + + /* Set up for the next time through */ + + rtrtcb = pndtcb; + } + + /* Mark the input list empty */ + + g_pendingtasks.head = NULL; + g_pendingtasks.tail = NULL; + + return ret; +} |