NuttX RTOS

git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@3 7fd9a85b-ad96-42d3-883c-3090e2eb8679

1 files changed, 498 insertions, 0 deletions

diff --git a/nuttx/sched/task_create.c b/nuttx/sched/task_create.c
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+/************************************************************
+ * task_create.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * 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 Gregory Nutt 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 <sys/types.h>
+#include <sched.h>
+#include <string.h>
+#include <errno.h>
+#include <nuttx/arch.h>
+#include <nuttx/os_external.h>
+#include "os_internal.h"
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/************************************************************
+ * Private Type Declarations
+ ************************************************************/
+
+/************************************************************
+ * Global Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Function Prototypes
+ ************************************************************/
+
+static void     task_start(void);
+static STATUS   task_assignpid(_TCB* tcb);
+
+/************************************************************
+ * Private Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: task_start
+ *
+ * Description:
+ *   This function is the low level entry point
+ *   into the main thread of execution of a task.  It receives
+ *   initial control when the task is started and calls main
+ *   entry point of the newly started task.
+ *
+ * Inputs:
+ *   None
+ *
+ * Return:
+ *   None
+ *
+ ************************************************************/
+
+static void task_start(void)
+{
+  _TCB *tcb = (_TCB*)g_readytorun.head;
+  int argc;
+
+  /* Count how many non-null arguments we are passing */
+
+  for (argc = 1; argc <= NUM_TASK_ARGS; argc++)
+    {
+       /* The first non-null argument terminates the list */
+
+       if (!tcb->argv[argc])
+         {
+           break;
+         }
+    }
+
+  /* Call the 'main' entry point passing argc and argv.  If/when
+   * the task returns,  */
+
+  exit(tcb->entry.main(argc, tcb->argv));
+}
+
+/************************************************************
+ * Name: task_assignpid
+ *
+ * Description:
+ *   This function assigns the next unique task ID to a task.
+ *
+ * Inputs:
+ *   tcb - TCB of task
+ *
+ * Return:
+ *   OK on success; ERROR on failure (errno is not set)
+ *
+ ************************************************************/
+
+static STATUS task_assignpid(_TCB *tcb)
+{
+  pid_t next_pid;
+  int   hash_ndx;
+  int   tries = 0;
+
+  /* Disable pre-emption.  This should provide sufficient protection
+   * for the following operation.
+   */
+
+  (void)sched_lock();
+
+  /* We'll try every allowable pid */
+
+  for (tries = 0; tries < MAX_TASKS_ALLOWED; tries++)
+    {
+      /* Get the next process ID candidate */
+
+      next_pid = ++g_lastpid;
+
+      /* Verify that the next_pid is in the valid range */
+
+      if (next_pid <= 0)
+        {
+          g_lastpid = 1;
+          next_pid  = 1;
+        }
+
+      /* Get the hash_ndx associated with the next_pid */
+
+      hash_ndx = PIDHASH(next_pid);
+
+      /* Check if there is a (potential) duplicate of this pid */
+
+      if (!g_pidhash[hash_ndx].tcb)
+        {
+          g_pidhash[hash_ndx].tcb = tcb;
+          g_pidhash[hash_ndx].pid = next_pid;
+          tcb->pid = next_pid;
+          (void)sched_unlock();
+          return OK;
+        }
+    }
+
+  /* If we get here, then the g_pidhash[] table is completely full.
+   * We cannot allow another task to be started.
+   */
+
+  (void)sched_unlock();
+  return ERROR;
+}
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: _task_init and task_init
+ *
+ * Description:
+ *   These functions initializes a Task Control Block (TCB)
+ *   in preparation for starting a new thread.  _task_init()
+ *   is an internal version of the function that has some
+ *   additional control arguments and task_init() is a wrapper
+ *   function that creates a VxWorks-like user API.
+ *   task_init() is, otherwise, not used by the OS.
+ *
+ *   _task_init() is called from task_init() and task_start().\
+ *   It is also called from pthread_create() to create a 
+ *   a pthread (distinguished by the pthread argument).
+ *
+ *   Unlike task_create(), task_init() does not activate the
+ *   task.  This must be done by calling task_activate()
+ *   afterward.
+ *
+ * Input Parameters:
+ *   tcb        - Address of the new task's TCB
+ *   name       - Name of the new task (not used)
+ *   priority   - Priority of the new task
+ *   entry      - Entry point of a new task
+ *   main       - Application start point of the new task
+ *   pthread    - TRUE is the task emulates pthread behavior
+ *   arg1-4     - Four required task arguments to pass to
+ *                the task when it is started.
+ *
+ * Return Value:
+ *  OK on success; ERROR on failure.
+ *
+ *  This function can only failure is it is unable to assign
+ *  a new, unique task ID to the TCB (errno is not set).
+ *
+ ************************************************************/
+
+STATUS _task_init(_TCB *tcb, char *name, int priority,
+                  start_t start, main_t main, boolean pthread,
+                  char *arg1, char *arg2, char *arg3, char *arg4)
+{
+  STATUS ret;
+
+  /* Assign a unique task ID to the task. */
+
+  ret = task_assignpid(tcb);
+  if (ret == OK)
+    {
+      /* Save task priority and entry point in the TCB */
+
+      tcb->init_priority  = (ubyte)priority;
+      tcb->sched_priority = (ubyte)priority;
+      tcb->start          = start;
+      tcb->entry.main     = main;
+
+#if CONFIG_TASK_NAME_SIZE > 0
+      /* Give a name to the unnamed threads */
+
+      if (!name)
+        {
+          name = "no name";
+        }
+
+      /* copy the name into the TCB */
+
+      strncpy(tcb->name, name, CONFIG_TASK_NAME_SIZE);
+#endif /* CONFIG_TASK_NAME_SIZE */
+
+      /* Save the arguments in the TCB */
+
+#if CONFIG_TASK_NAME_SIZE > 0
+      tcb->argv[0] = tcb->name;
+#else
+      tcb->argv[0] = "no name";
+#endif
+
+      /* For pthreads, args are strictly pass-by-value; the char*
+       * arguments wrap some unknown value cast to char*.  However,
+       * for tasks, the life of the argument must be as long as
+       * the life of the task and the arguments must be strings.
+       * So for tasks, we have to to dup the strings.
+       */
+
+      if (!pthread)
+        {
+          /* The first NULL argument terminates the list of 
+           * arguments.
+           */
+
+          if (arg1)
+            {
+              tcb->argv[1] = strdup(arg1);
+              if (arg2)
+                {
+                  tcb->argv[2] = strdup(arg2);
+                  if (arg3)
+                    {
+                      tcb->argv[3] = strdup(arg3);
+                      if (arg4)
+                        {
+                          tcb->argv[4] = strdup(arg4);
+                        }
+                    }
+                }
+            }
+        }
+      else
+        {
+          /* Mark this task as a pthread */
+
+          tcb->flags   |= TCB_FLAG_PTHREAD;
+
+          /* And just copy the argument.  (For pthreads, there
+           * is really only a single argument, arg1).
+           */
+
+          tcb->argv[1]  = arg1;
+          tcb->argv[2]  = arg2;
+          tcb->argv[3]  = arg3;
+          tcb->argv[4]  = arg4;
+        }
+
+      /* Initialize other (non-zero) elements of the TCB */
+
+      tcb->sigprocmask  = ALL_SIGNAL_SET;
+      tcb->task_state    = TSTATE_TASK_INVALID;
+
+      /* Initialize the processor-specific portion of the TCB */
+
+      up_initial_state(tcb);
+
+      /* Add the task to the inactive task list */
+
+      sched_lock();
+      dq_addfirst((dq_entry_t*)tcb, &g_inactivetasks);
+      tcb->task_state = TSTATE_TASK_INACTIVE;
+      sched_unlock();
+    }
+
+ return ret;
+}
+
+/************************************************************
+ * Name: _task_init and task_init
+ *
+ * Description:
+ *   This is a wrapper around the internal _task_init() that
+ *   provides a VxWorks-like API.  See _task_init() for
+ *   further information.
+ *
+ * Input Parameters:
+ *   tcb        - Address of the new task's TCB
+ *   name       - Name of the new task (not used)
+ *   priority   - Priority of the new task
+ *   stack      - start of the pre-allocated stack
+ *   stack_size - size (in bytes) of the stack allocated
+ *   entry      - Application start point of the new task
+ *   arg1-4     - Four required task arguments to pass to
+ *                the task when it is started.
+ *
+ * Return Value:
+ *   see _task_init()
+ *
+ ************************************************************/
+
+STATUS task_init(_TCB *tcb, char *name, int priority,
+                 uint32 *stack, uint32 stack_size, main_t entry,
+                 char *arg1, char *arg2, char *arg3, char *arg4)
+{
+  up_use_stack(tcb, stack, stack_size);
+  return _task_init(tcb, name, priority, task_start, entry,
+                    FALSE, arg1, arg2, arg3, arg4);
+}
+
+/************************************************************
+ * Name: task_activate
+ *
+ * Description:
+ *   This function activates tasks initialized by _task_init().
+ *   Without activation, a task is ineligible for execution
+ *   by the scheduler.
+ *
+ * Input Parameters:
+ *   tcb - The TCB for the task for the task (same as the
+ *         task_init argument.
+ *
+ * Return Value:
+ *  Always returns OK
+ *
+ ************************************************************/
+
+STATUS task_activate(_TCB *tcb)
+{
+#ifdef CONFIG_SCHED_INSTRUMENTATION
+   uint32  savedState;
+#endif
+
+#ifdef CONFIG_SCHED_INSTRUMENTATION
+   savedState = irqsave();
+
+   /* Check if this is really a re-start */
+
+   if (tcb->task_state != TSTATE_TASK_INACTIVE)
+     {
+       /* Inform the instrumentation layer that the task
+        * has stopped
+        */
+
+       sched_note_stop(tcb);
+     }
+
+   /* Inform the instrumentation layer that the task
+    * has started
+    */
+
+   sched_note_start(tcb);
+   irqrestore(savedState);
+#endif
+
+   up_unblock_task(tcb);
+   return OK;
+}
+
+/************************************************************
+ * Name: task_create
+ *
+ * Description:
+ *   This function creates and activates a new task with a
+ *   specified priority and returns its system-assigned ID.
+ *
+ *   The entry address entry is the address of the "main"
+ *   function of the task.  This function will be called once
+ *   the C environment has been set up.  The specified
+ *   function will be called with four arguments.  Should
+ *   the specified routine return, a call to exit() will
+ *   automatically be made.
+ *
+ *   Note that four (and only four) arguments must be passed for
+ *   the spawned functions.
+ *
+ * Input Parameters:
+ *   name       - Name of the new task
+ *   priority   - Priority of the new task
+ *   stack_size - size (in bytes) of the stack needed
+ *   entry      - Entry point of a new task
+ *   arg*       - Ten required task arguments to pass to func
+ *
+ * Return Value:
+ *   Returns the non-zero process ID of the new task or
+ *   ERROR if memory is insufficient or the task cannot be
+ *   created (errno is not set).
+ *
+ ************************************************************/
+
+int task_create(char *name, int priority,
+                int stack_size, main_t entry,
+                char *arg1, char *arg2, char *arg3, char *arg4)
+{
+  _TCB *tcb;
+  STATUS status;
+  pid_t pid;
+
+  /* Allocate a TCB for the new task. */
+
+  tcb = (_TCB*)kzmalloc(sizeof(_TCB));
+  if (!tcb)
+    {
+      *get_errno_ptr() = ENOMEM;
+      return ERROR;
+    }
+
+  /* Associate file descriptors with the new task */
+
+  if (sched_setuptaskfiles(tcb) != OK)
+    {
+      sched_releasetcb(tcb);
+      return ERROR;
+    }
+
+  /* Allocate the stack for the TCB */
+
+  status = up_create_stack(tcb, stack_size);
+  if (status != OK)
+    {
+      sched_releasetcb(tcb);
+      return ERROR;
+    }
+
+   /* Initialize the task control block */
+
+   status = _task_init(tcb, name, priority, task_start, entry,
+                       FALSE, arg1, arg2, arg3, arg4);
+   if (status != OK)
+     {
+       sched_releasetcb(tcb);
+       return ERROR;
+     }
+
+   /* Get the assigned pid before we start the task */
+
+   pid = (int)tcb->pid;
+
+   /* Activate the task */
+
+   status = task_activate(tcb);
+   if (status != OK)
+    {
+      dq_rem((dq_entry_t*)tcb, &g_inactivetasks);
+      sched_releasetcb(tcb);
+      return ERROR;
+    }
+
+   return pid;
+}