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>Thread information</TITLE
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>eCos Reference Manual</TH
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><H1
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><A
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NAME="KERNEL-THREAD-INFO">Thread information</H1
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><DIV
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CLASS="REFNAMEDIV"
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><A
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NAME="AEN356"
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></A
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><H2
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>Name</H2
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>cyg_thread_self, cyg_thread_idle_thread, cyg_thread_get_stack_base, cyg_thread_get_stack_size, cyg_thread_measure_stack_usage, cyg_thread_get_next, cyg_thread_get_info, cyg_thread_find&nbsp;--&nbsp;Get basic thread information</DIV
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><DIV
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CLASS="REFSYNOPSISDIV"
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><A
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NAME="AEN366"><H2
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>Synopsis</H2
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><DIV
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CLASS="FUNCSYNOPSIS"
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><A
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NAME="AEN367"><P
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></P
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><TABLE
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
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><TD
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><PRE
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CLASS="FUNCSYNOPSISINFO"
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>#include &lt;cyg/kernel/kapi.h&gt;
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        </PRE
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></TD
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></TR
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></TABLE
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>cyg_handle_t cyg_thread_self</CODE
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>(void);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>cyg_handle_t cyg_thread_idle_thread</CODE
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>(void);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>cyg_addrword_t cyg_thread_get_stack_base</CODE
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>(cyg_handle_t thread);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>cyg_uint32 cyg_thread_get_stack_size</CODE
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>(cyg_handle_t thread);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>cyg_uint32 cyg_thread_measure_stack_usage</CODE
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>(cyg_handle_t thread);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>cyg_bool cyg_thread_get_next</CODE
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>(cyg_handle_t *thread, cyg_uint16 *id);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
160 
>cyg_bool cyg_thread_get_info</CODE
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>(cyg_handle_t thread, cyg_uint16 id, cyg_thread_info *info);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
167 
>cyg_handle_t cyg_thread_find</CODE
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>(cyg_uint16 id);</CODE
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></P
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><P
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></P
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></DIV
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="KERNEL-THREAD-INFO-DESCRIPTION"
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></A
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><H2
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>Description</H2
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><P
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>These functions can be used to obtain some basic information about
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various threads in the system. Typically they serve little or no
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purpose in real applications, but they can be useful during debugging.
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      </P
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><P
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><TT
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CLASS="FUNCTION"
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>cyg_thread_self</TT
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> returns a handle corresponding
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to the current thread. It will be the same as the value filled in by
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<TT
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CLASS="FUNCTION"
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>cyg_thread_create</TT
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> when the current thread was
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created. This handle can then be passed to other functions such as
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<TT
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CLASS="FUNCTION"
199 
>cyg_thread_get_priority</TT
200 
>.
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      </P
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><P
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><TT
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CLASS="FUNCTION"
205 
>cyg_thread_idle_thread</TT
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> returns the handle
207 
corresponding to the idle thread. This thread is created automatically
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by the kernel, so application-code has no other way of getting hold of
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this information.
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      </P
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><P
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><TT
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CLASS="FUNCTION"
214 
>cyg_thread_get_stack_base</TT
215 
> and
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<TT
217 
CLASS="FUNCTION"
218 
>cyg_thread_get_stack_size</TT
219 
> return information
220 
about a specific thread's stack. The values returned will match the
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values passed to <TT
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CLASS="FUNCTION"
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>cyg_thread_create</TT
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> when this
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thread was created.
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      </P
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><P
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><TT
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CLASS="FUNCTION"
230 
>cyg_thread_measure_stack_usage</TT
231 
> is only available
232 
if the configuration option
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<TT
234 
CLASS="VARNAME"
235 
>CYGFUN_KERNEL_THREADS_STACK_MEASUREMENT</TT
236 
> is enabled.
237 
The return value is the maximum number of bytes of stack space used so
238 
far by the specified thread. Note that this should not be considered a
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true upper bound, for example it is possible that in the current test
240 
run the specified thread has not yet been interrupted at the deepest
241 
point in the function call graph. Never the less the value returned
242 
can give some useful indication of the thread's stack requirements.
243 
      </P
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><P
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><TT
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CLASS="FUNCTION"
247 
>cyg_thread_get_next</TT
248 
> is used to enumerate all the
249 
current threads in the system. It should be called initially with the
250 
locations pointed to by <TT
251 
CLASS="PARAMETER"
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><I
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>thread</I
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></TT
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> and
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<TT
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CLASS="PARAMETER"
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><I
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>id</I
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></TT
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> set to zero. On return these will be set to
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the handle and ID of the first thread. On subsequent calls, these
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parameters should be left set to the values returned by the previous
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call.  The handle and ID of the next thread in the system will be
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installed each time, until a <TT
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CLASS="LITERAL"
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>false</TT
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> return value
269 
indicates the end of the list.
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      </P
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><P
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><TT
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CLASS="FUNCTION"
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>cyg_thread_get_info</TT
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> fills in the
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<SPAN
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CLASS="TYPE"
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>cyg_thread_info</SPAN
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> structure with information about the
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thread described by the <TT
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CLASS="PARAMETER"
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><I
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>thread</I
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></TT
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> and
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<TT
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CLASS="PARAMETER"
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><I
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>id</I
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></TT
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> arguments. The information returned includes
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the thread's handle and id, its state and name, priorities and stack
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parameters. If the thread does not exist the function returns
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<TT
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CLASS="LITERAL"
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>false</TT
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>.
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    </P
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><P
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>The <SPAN
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CLASS="TYPE"
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>cyg_thread_info</SPAN
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> structure is defined as follows by
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&lt;<TT
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CLASS="FILENAME"
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>cyg/kernel/kapi.h</TT
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>&gt;, but may
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be extended in future with additional members, and so its size should
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not be relied upon:
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<TABLE
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
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><TD
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><PRE
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CLASS="PROGRAMLISTING"
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>typedef struct
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{
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    <SPAN
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CLASS="TYPE"
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>cyg_handle_t</SPAN
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>        <TT
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CLASS="STRUCTFIELD"
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><I
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>handle</I
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></TT
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>;
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    <SPAN
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CLASS="TYPE"
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>cyg_uint16</SPAN
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>          <TT
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CLASS="STRUCTFIELD"
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><I
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>id</I
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></TT
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>;
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    <SPAN
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CLASS="TYPE"
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>cyg_uint32</SPAN
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>          <TT
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CLASS="STRUCTFIELD"
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><I
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>state</I
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></TT
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>;
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    <SPAN
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CLASS="TYPE"
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>char</SPAN
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>                <TT
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CLASS="STRUCTFIELD"
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><I
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>*name</I
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></TT
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>;
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    <SPAN
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CLASS="TYPE"
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>cyg_priority_t</SPAN
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>      <TT
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CLASS="STRUCTFIELD"
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><I
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>set_pri</I
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></TT
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>;
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    <SPAN
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CLASS="TYPE"
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>cyg_priority_t</SPAN
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>      <TT
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CLASS="STRUCTFIELD"
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><I
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>cur_pri</I
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></TT
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>;
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    <SPAN
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CLASS="TYPE"
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>cyg_addrword_t</SPAN
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>      <TT
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CLASS="STRUCTFIELD"
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><I
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>stack_base</I
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></TT
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>;
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    <SPAN
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CLASS="TYPE"
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>cyg_uint32</SPAN
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>          <TT
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CLASS="STRUCTFIELD"
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><I
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>stack_size</I
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></TT
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>;
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    <SPAN
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CLASS="TYPE"
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>cyg_uint32</SPAN
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>          <TT
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CLASS="STRUCTFIELD"
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><I
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>stack_used</I
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></TT
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>;
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} cyg_thread_info;</PRE
402 
></TD
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></TR
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></TABLE
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>
406 
    </P
407 
><P
408 
><TT
409 
CLASS="FUNCTION"
410 
>cyg_thread_find</TT
411 
> returns a handle for the thread
412 
whose ID is <TT
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CLASS="PARAMETER"
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><I
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>id</I
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></TT
417 
>. If no such thread exists, a
418 
zero handle is returned.
419 
    </P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="KERNEL-THREAD-INFO-CONTEXT"
425 
></A
426 
><H2
427 
>Valid contexts</H2
428 
><P
429 
><TT
430 
CLASS="FUNCTION"
431 
>cyg_thread_self</TT
432 
> may only be called from thread
433 
context. <TT
434 
CLASS="FUNCTION"
435 
>cyg_thread_idle_thread</TT
436 
> may be called
437 
from thread or DSR context, but only after the system has been
438 
initialized. <TT
439 
CLASS="FUNCTION"
440 
>cyg_thread_get_stack_base</TT
441 
>,
442 
<TT
443 
CLASS="FUNCTION"
444 
>cyg_thread_get_stack_size</TT
445 
> and
446 
<TT
447 
CLASS="FUNCTION"
448 
>cyg_thread_measure_stack_usage</TT
449 
> may be called
450 
any time after the specified thread has been created, but measuring
451 
stack usage involves looping over at least part of the thread's stack
452 
so this should normally only be done from thread context.
453 
      </P
454 
></DIV
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><DIV
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CLASS="REFSECT1"
457 
><A
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NAME="KERNEL-THREAD-INFO-EXAMPLES"
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></A
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><H2
461 
>Examples</H2
462 
><P
463 
>A simple example of the use of the
464 
<TT
465 
CLASS="FUNCTION"
466 
>cyg_thread_get_next</TT
467 
> and
468 
<TT
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CLASS="FUNCTION"
470 
>cyg_thread_get_info</TT
471 
> follows:
472 
      </P
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><TABLE
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
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><TD
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><PRE
480 
CLASS="PROGRAMLISTING"
481 
>&#13;#include &lt;cyg/kernel/kapi.h&gt;
482 
#include &lt;stdio.h&gt;
483 
 
484 
void show_threads(void)
485 
{
486 
    cyg_handle_t thread = 0;
487 
    cyg_uint16 id = 0;
488 
 
489 
    while( cyg_thread_get_next( &amp;thread, &amp;id ) )
490 
    {
491 
        cyg_thread_info info;
492 
 
493 
        if( !cyg_thread_get_info( thread, id, &amp;info ) )
494 
            break;
495 
 
496 
        printf("ID: %04x name: %10s pri: %d\n",
497 
                info.id, info.name?info.name:"----", info.set_pri );
498 
    }
499 
}
500 
 
501 
      </PRE
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></TD
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