task_create now accepts variable number of arguments; 8051 bringup changes
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@56 42af7a65-404d-4744-a932-0658087f49c3
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@ -12,7 +12,7 @@
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<hr>
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<hr>
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<CENTER><BIG><B>
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Nuttx Operating System
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NuttX Operating System
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<P>
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User's Manual
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</B></BIG>
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@ -30,9 +30,9 @@ Gregory Nutt
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This user's manual is divided into three sections:
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<UL>
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<LI><B>Section 1.0, <A HREF="#Introduction">Introduction</A></B>:
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This section provides an overview of the Nuttx user's manual.
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This section provides an overview of the NuttX user's manual.
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<LI><B>Section 2.0, <A HREF="#OS_Interfaces">OS Interfaces</A></B>:
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This section details the interfaces provided by Nuttx from the
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This section details the interfaces provided by NuttX from the
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perspective of the firmware developer. This section is divided
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into several paragraphs that describe different groups of OS interfaces:
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<UL>
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@ -46,7 +46,7 @@ into several paragraphs that describe different groups of OS interfaces:
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<LI>Paragraph 2.8 <A HREF="#Pthread">Pthread Interfaces</A>
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</UL>
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<LI><B>Section 3.0, <A HREF="#Data_Structures">OS Data Structures</A></B>:
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This section documents the data structures that are used at the Nuttx
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This section documents the data structures that are used at the NuttX
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interface.
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</UL>
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<HR>
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@ -54,7 +54,7 @@ interface.
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<H1>2.0 <A NAME="OS_Interfaces">OS Interfaces</A></H1>
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<P>
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This section describes each C-callable interface to the Nuttx
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This section describes each C-callable interface to the NuttX
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Operating System. The description of each interface is presented
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in the following format:
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<P>
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@ -77,10 +77,10 @@ the interface function or any non-obvious limitations to the use
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of the interface function will be indicated here.
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<P>
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<B>POSIX Compatibility:</B> Any significant differences between the
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Nuttx interface and its corresponding POSIX interface will be noted
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NuttX interface and its corresponding POSIX interface will be noted
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here.
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<P>
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NOTE: In order to achieve an independent name space for the Nuttx
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NOTE: In order to achieve an independent name space for the NuttX
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interface functions, differences in function names and types are
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to be expected and will not be identified as differences in these
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paragraphs.
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@ -90,9 +90,9 @@ paragraphs.
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<p>
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<b>Tasks</b>.
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Nuttx is a flat address OS. As such it does not support "processes"
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NuttX is a flat address OS. As such it does not support "processes"
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in the way that, say, Linux does.
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Nuttx only supports simple threads running within the same address space.
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NuttX only supports simple threads running within the same address space.
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However, the programming model makes a distinction between "tasks"
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and pthreads:
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<ul>
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@ -129,7 +129,7 @@ were started from the same parent thread.
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int priority,
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int stack_size,
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main_t entry,
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char *arg1, char *arg2, char *arg3, char *arg4);
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const char *argv[]);
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</PRE>
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<P>
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@ -144,17 +144,28 @@ were started from the same parent thread.
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The specified function will be called with four arguments.
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Should the specified routine return, a call to exit() will automatically be made.
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</P>
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<P>
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Note that four (and only four) arguments must be passed for the
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spawned functions.
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</P>
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<p>
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The newly created task does not inherity characteristics
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Note that an arbitrary number of arguments may be passed to the
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spawned functions. The maximum umber of arguments is an OS
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configuration parameter (<code>CONFIG_MAX_TASK_ARGS</code>).
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</p>
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<p>
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The arguments are copied (via <code>strdup</code>) so that the
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life of the passed strings is not dependent on the life of the
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caller to <code>task_create()</code>.
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</p>
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<p>
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The newly created task does not inherit scheduler characteristics
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from the parent task: The new task is started at the
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default system priority and with the SCHED_FIFO scheduling
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policy. These characteristcs may be modified after the new
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task has been started.
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</p>
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<p>
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The newly created task does inherit the first three file
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descriptors (corresponding to stdin, stdout, and stderr) and
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redirection of standard I/O is supported.
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</p>
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<P>
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<B>Input Parameters:</B>
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<UL>
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@ -162,7 +173,11 @@ were started from the same parent thread.
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<LI><I>priority</I>. Priority of the new task</LI>
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<LI><I>stack_size</I>. size (in bytes) of the stack needed</LI>
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<LI><I>entry</I>. Entry point of a new task</LI>
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<LI><I>arg1, arg2, arg3, and arg4</I>. Four required task arguments to pass to the task</LI>
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<LI><I>argv</I>. A pointer to an array of input parameters. Up to
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<code>CONFIG_MAX_TASK_ARG</code> parameters may be provided.
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If fewer than <code>CONFIG_MAX_TASK_ARG</code> parameters are
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passed, the list should be terminated with a NULL argv[] value.
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If no parameters are required, argv may be NULL.
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</UL>
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<P>
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<B>Returned Values:</B>
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@ -192,14 +207,13 @@ VxWorks provides the following similar interface:
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</PRE>
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<P>
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The Nuttx task_create() differs from VxWorks' taskSpawn() in the
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The NuttX task_create() differs from VxWorks' taskSpawn() in the
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following ways:
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<UL>
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<LI>Function name
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<LI>Various differences in types or arguments
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<LI>Interface name
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<LI>Various differences in types of arguments
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<LI>There is no options arguement.
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<LI>One four parameters can be passed to a task (VxWorks allows
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ten).
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<LI>A variable number of parameters can be passed to a task (VxWorks supports ten).
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</UL>
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<H3>2.1.2 task_init</H3>
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@ -215,14 +229,15 @@ ten).
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uint32 *stack,
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uint32 stack_size,
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maint_t entry,
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int arg1, int arg2, int arg3, int arg4);
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const char *argv[]);
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</PRE>
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<P>
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<B>Description:</B>
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<P>
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This function initializes a Task Control Block (TCB)
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in preparation for starting a new thread.
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in preparation for starting a new thread. It performs a subset
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of the functionality of <code>task_create()</code> (see above).
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</P>
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<P>
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Unlike task_create(), task_init() does not activate the task.
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@ -237,7 +252,11 @@ ten).
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<LI><I>stack</I>. Start of the pre-allocated stack
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<LI><I>stack_size</I>. size (in bytes) of the pre-allocated stack
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<LI><I>entry</I>. Entry point of a new task
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<LI><I>arg1, arg2, arg3, and arg4</I>. Four required task arguments to pass to the task
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<LI><I>argv</I>. A pointer to an array of input parameters. Up to
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<code>CONFIG_MAX_TASK_ARG</code> parameters may be provided.
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If fewer than <code>CONFIG_MAX_TASK_ARG</code> parameters are
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passed, the list should be terminated with a NULL argv[] value.
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If no parameters are required, argv may be NULL.
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</UL>
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</p>
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<P>
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@ -272,13 +291,13 @@ VxWorks provides the following similar interface:
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</PRE>
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<P>
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The Nuttx task_init() differs from VxWorks' taskInit() in the
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The NuttX task_init() differs from VxWorks' taskInit() in the
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following ways:
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<UL>
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<LI>Function name
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<LI>Interface name
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<LI>Various differences in types or arguments
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<LI>There is no options argument.
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<LI>One four parameters can be passed to a task (VxWorks allows ten).
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<LI>A variable number of parameters can be passed to a task (VxWorks supports ten).
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</UL>
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<H3>2.1.3 task_activate</H3>
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@ -322,7 +341,7 @@ VxWorks provides the following similar interface:
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</PRE>
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<P>
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The Nuttx task_activate() differs from VxWorks' taskActivate() in the
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The NuttX task_activate() differs from VxWorks' taskActivate() in the
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following ways:
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<UL>
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<LI>Function name
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@ -371,7 +390,7 @@ VxWorks provides the following similar interface:
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</PRE>
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<P>
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The Nuttx task_delete() differs from VxWorks' taskDelete() in
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The NuttX task_delete() differs from VxWorks' taskDelete() in
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the following ways:
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<UL>
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<LI>No support is provided for calling the tasks deletion routines
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@ -419,7 +438,7 @@ And the unix interface:
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</PRE>
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<P>
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The Nuttx exit() differs from ANSI exit() in
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The NuttX exit() differs from ANSI exit() in
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the following ways:
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<UL>
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<LI>The <I>code</I> parameter is ignored.
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@ -468,7 +487,7 @@ VxWorks provides the following similar interface:
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</PRE>
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<P>
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The Nuttx task_restart() differs from VxWorks' taskRestart() in
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The NuttX task_restart() differs from VxWorks' taskRestart() in
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the following ways:
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<UL>
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<LI>Restart of the currently running task is not supported.
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@ -506,15 +525,15 @@ Compatible with the POSIX interface of the same name.
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<H2>2.2 <A NAME="Task_Schedule">Task Scheduling Interfaces</A></H2>
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<P>
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Nuttx performs strict priority scheduling: Tasks of higher
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NuttX performs strict priority scheduling: Tasks of higher
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priority have exclusive access to the CPU until they become blocked.
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At that time, the CPU is available to tasks of lower priority.
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Tasks of equal priority are scheduled FIFO.
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<P>
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The OS interfaces described in the following paragraphs provide
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a POSIX- compliant interface to the Nuttx scheduler. However, these
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a POSIX- compliant interface to the NuttX scheduler. However, these
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POSIX interfaces assume a greater range of scheduling options
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than those provided by the Nuttx scheduler. As a result, many of
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than those provided by the NuttX scheduler. As a result, many of
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these POSIX interfaces are little more than stubs.
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<H3>2.2.1 sched_setparam</H3>
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@ -921,7 +940,7 @@ on this thread of execution.
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<H2>2.4 <A NAME="Message_Queue">Named Message Queue Interfaces</A></H2>
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<P>
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The Nuttx supports POSIX named message queues for intertask communication.
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The NuttX supports POSIX named message queues for intertask communication.
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Any task may send or receive messages on named message queues.
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Interrupt handlers may send messages via named message queues.
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@ -1305,7 +1324,7 @@ interface of the same name.
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<P>
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<B>Semaphores</B>. Semaphores are the basis for
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synchronization and mutual exclusion in Nuttx. Nuttx supports
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synchronization and mutual exclusion in NuttX. NuttX supports
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POSIX semaphores.
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<P>
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Semaphores are the preferred mechanism for gaining exclusive access to a
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@ -1336,7 +1355,7 @@ inversion</I>.
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<P>
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Some operating systems avoid priority inversion by <I>automatically</I>
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increasing the priority of the low-priority <I>Task C</I> (the operable
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buzz-word for this behavior is <I>mutex</I> semaphores). The Nuttx does not
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buzz-word for this behavior is <I>mutex</I> semaphores). The NuttX does not
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support this behavior. As a consequence, it is left to the designer to
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provide implementations that will not suffer from priority inversion.
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The designer may, as examples:
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@ -1757,13 +1776,13 @@ interface of the same name.
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<H2>2.6 <A NAME="Watchdogs">Watchdog Timer Interfaces</A></H2>
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<P>
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The Nuttx provides a general watchdog timer facility. This
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facility allows the Nuttx user to specify a watchdog timer function
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The NuttX provides a general watchdog timer facility. This
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facility allows the NuttX user to specify a watchdog timer function
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that will run after a specified delay. The watchdog timer function
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will run in the context of the timer interrupt handler. Because
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of this, a limited number of Nuttx interfaces are available to
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of this, a limited number of NuttX interfaces are available to
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the watchdog timer function. However, the watchdog timer function
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may use mq_send(), and sigqueue() to communicate with Nuttx tasks.
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may use mq_send(), and sigqueue() to communicate with NuttX tasks.
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<H3>2.6.1 wd_create</H3>
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@ -1783,7 +1802,7 @@ by allocating the appropriate resources for the watchdog.
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<B>Returned Values:</B>
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<UL>
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<LI>Pointer to watchdog that may be used as a handle in subsequent
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Nuttx calls (i.e., the watchdog ID), or NULL if insufficient resources
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NuttX calls (i.e., the watchdog ID), or NULL if insufficient resources
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are available to create the watchdogs.
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</UL>
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@ -1946,7 +1965,7 @@ VxWorks provides the following comparable interface:
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<H2>2.7 <A NAME="Signals">Signal Interfaces</A></H2>
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<P>
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The Nuttx provides signal interfaces for tasks. Signals are
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The NuttX provides signal interfaces for tasks. Signals are
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used to alter the flow control of tasks by communicating asynchronous
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events within or between task contexts. Any task or interrupt
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handler can post (or send) a signal to a particular task. The
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<H1>3.0 <A NAME="Data_Structures">OS Data Structures</A></H1>
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<H2>3.1 Scalar types</H2>
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<P>
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Many of the types used to communicate with Nuttx are simple
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Many of the types used to communicate with NuttX are simple
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scalar types. These types are used to provide architecture independence
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of the OS from the application. The scalar types used at the Nuttx
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of the OS from the application. The scalar types used at the NuttX
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interface include:
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<UL>
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<LI>pid_t
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@ -3927,7 +3946,7 @@ interface include:
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<H2>3.2 Hidden Interface Structures</H2>
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<P>
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Several of the types used to interface with Nuttx are
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Several of the types used to interface with NuttX are
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structures that are intended to be hidden from the application.
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From the standpoint of the application, these structures (and
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structure pointers) should be treated as simple handles to reference
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@ -3984,7 +4003,7 @@ in sys/types.h as:
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<P>
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This structure is used to pass scheduling priorities to and from
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Nuttx;
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NuttX;
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<PRE>
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struct sched_param
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{
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@ -3996,7 +4015,7 @@ Nuttx;
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<P>
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This structure is used to pass timing information between the
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Nuttx and a user application:
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NuttX and a user application:
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<PRE>
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struct timespec
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{
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@ -4009,7 +4028,7 @@ Nuttx and a user application:
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<P>
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This structure is used to communicate message queue attributes
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between Nuttx and a MoBY application:
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between NuttX and a MoBY application:
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<PRE>
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struct mq_attr {
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size_t mq_maxmsg; /* Max number of messages in queue */
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