<part id="compat-uitron">
  <title>&micro;ITRON</title>
<CHAPTER id="compat-uitron-microitron-api">
<TITLE><!-- <xref> -->&micro;ITRON API</TITLE>
<SECT1 id="compat-uitron-introduction">
<TITLE><!-- <index></index> -->Introduction to &micro;ITRON</TITLE>
<PARA>The <!-- <index></index> -->&micro;ITRON specification
defines a highly flexible operating system architecture designed
specifically for application in embedded systems. The specification addresses
features which are common to the majority of processor architectures and
deliberately avoids virtualization which would adversely impact
real-time performance. The &micro;ITRON specification
may be implemented on many hardware platforms and provides significant
advantages by reducing the effort involved in understanding and
porting application software to new processor architectures. </PARA>
<PARA>Several revisions of the &micro;ITRON specification exist.
	In this release, <EMPHASIS>eCos</EMPHASIS> supports the
	&micro;ITRON version 3.02 specification, with complete
	&ldquo;Standard functionality&rdquo; (level S), plus many
	&ldquo;Extended&rdquo; (level E) functions. The definitive
	reference on &micro;ITRON is Dr. Sakamura&rsquo;s book:
	  <CITETITLE>&micro;ITRON 3.0, An Open and Portable Real-Time Operating
	  System for Embedded Systems</CITETITLE>. 
	The book can be purchased from the IEEE Press, and
	an ASCII version of the standard can be found online at
<ulink url="http://www.itron.gr.jp/">http://www.itron.gr.jp/</ulink>.
The old address 
<ulink url="http://tron.um.u-tokyo.ac.jp/TRON/ITRON/">
http://tron.um.u-tokyo.ac.jp/TRON/ITRON/</ulink>
still exists as a mirror site. </PARA>
</SECT1>
<SECT1 id="compat-uitron-over-ecos">
<TITLE><!-- <index></index> -->&micro;ITRON and <EMPHASIS>eCos</EMPHASIS></TITLE>
<PARA>The <EMPHASIS>eCos</EMPHASIS> kernel implements the functionality
used by the &micro;ITRON compatibility subsystem.
The configuration of the kernel influences the behavior of &micro;ITRON
programs.</PARA>
<PARA>In particular, the default configuration has time slicing
(also known as round-robin scheduling) switched on; this means that
a task can be moved from <varname>RUN</varname> state
to <varname>READY</varname> state at any time, in
order that one of its peers may run. This is not strictly conformant
to the &micro;ITRON specification, which
states that timeslicing may be implemented by periodically issuing
a <literal>rot_rdq(0)</literal> call from
within a periodic task or cyclic handler; otherwise it is expected
that a task runs until it is pre-empted in consequence of synchronization
or communication calls it makes, or the effects of an interrupt
or other external event on a higher priority task cause that task
to become <varname>READY</varname>. To disable timeslicing
functionality in the kernel and &micro;ITRON
compatibility environment, please disable the 
<LITERAL>CYGSEM_KERNEL_SCHED_TIMESLICE</LITERAL>
configuration option in the kernel package. A description of kernel
scheduling is in <xref linkend="kernel-overview">. </PARA>
<PARA>For another example, the semantics of task queueing when waiting
on a synchronization object depend solely on the way the underlying
kernel is configured. As discussed above, the multi-level queue
scheduler is the only one which is &micro;ITRON
compliant, and it queues waiting tasks in FIFO order. Future releases
of that scheduler might be configurable to support priority ordering
of task queues. Other schedulers might be different again: for example
the bitmap scheduler can be used with the &micro;ITRON
compatibility layer, even though it only allows one task at each
priority and as such is not &micro;ITRON
compliant, but it supports only priority ordering of task queues.
So which queueing scheme is supported is not really a property of
the &micro;ITRON compatibility layer; it
depends on the kernel. </PARA>
<PARA>In this version of the &micro;ITRON
compatibility layer, the calls to disable and enable scheduling
and interrupts (<FUNCTION>dis_dsp()</FUNCTION>,
<FUNCTION>ena_dsp()</FUNCTION>, <FUNCTION>loc_cpu()</FUNCTION>
and <FUNCTION>unl_cpu()</FUNCTION>)
call underlying kernel functions; in particular, the <FUNCTION>xxx_dsp()</FUNCTION> functions
lock the scheduler entirely, which prevents dispatching of DSRs; functions
implemented by DSRs include clock counters and alarm timers. Thus time &ldquo;stops&rdquo; while
dispatching is disabled with <FUNCTION>dis_dsp()</FUNCTION>. </PARA>
<PARA>Like all parts of the <EMPHASIS>eCos</EMPHASIS> system, the
detailed semantics of the &micro;ITRON layer
are dependent on its configuration and the configuration of other components
that it uses. The &micro;ITRON configuration
options are all defined in the file <filename>pkgconf/uitron.h</filename>,
and can be set using the configuration tool or editing the
<filename>.ecc</filename>
file in your build directory by hand. </PARA>
<PARA>An important configuration option for the &micro;ITRON
compatibility layer is &ldquo;Option: Return Error Codes for Bad Params&rdquo;
(
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
), which allows a lot of the error
checking code in the &micro;ITRON compatibility layer to
be removed. Of course this leaves a program open to undetected errors,
so it should only be used once an application is fully debugged and
tested. Its benefits include reduced code size and faster execution.
However, it affects the API significantly, in that with this option
enabled, bad calls do not return errors, but cause an assert
failure (if that is itself enabled) or malfunction internally. There
is discussion in more detail about this in each section below.</PARA>
<PARA>We now give a brief description of the &micro;ITRON
functions which are implemented in this release. Note that all C
and C&plus;&plus; source files should have the following <literal>#include</literal> statement: </PARA>
<PROGRAMLISTING>#include &lt;cyg/compat/uitron/uit_func.h&gt;</PROGRAMLISTING>
</SECT1>
<SECT1 id="compat-uitron-task-management-functions">
<TITLE><!-- <index></index> -->Task Management Functions</TITLE>
<PARA>The following functions are fully supported in this release: </PARA>
<PROGRAMLISTING>ER <FUNCTION>sta_tsk</FUNCTION>( 
  ID <EMPHASIS>tskid,</EMPHASIS>
  INT <EMPHASIS>stacd</EMPHASIS> )</programlisting>
	<programlisting>
void <FUNCTION>ext_tsk</FUNCTION>( void )</programlisting>
	<programlisting>
void <FUNCTION>exd_tsk</FUNCTION>( void )</programlisting>
	<programlisting>
ER <FUNCTION>dis_dsp</FUNCTION>( void )</programlisting>
	<programlisting>
ER <FUNCTION>ena_dsp</FUNCTION>( void )</programlisting>
	<programlisting>
ER <FUNCTION>chg_pri</FUNCTION>( 
  ID <EMPHASIS>tskid,</EMPHASIS>
  PRI <EMPHASIS>tskpri</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>rot_rdq</FUNCTION>( 
  PRI <EMPHASIS>tskpri</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>get_tid</FUNCTION>( 
  ID *<EMPHASIS>p_tskid</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>ref_tsk</FUNCTION>( 
  T_RTSK *<EMPHASIS>pk_rtsk,</EMPHASIS>
  ID <EMPHASIS>tskid</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>ter_tsk</FUNCTION>( 
  ID <EMPHASIS>tskid</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>rel_wai</FUNCTION>( 
  ID <EMPHASIS>tskid</EMPHASIS> )</PROGRAMLISTING>
<PARA>The following two functions are supported in this release,
when enabled with the configuration option 
<LITERAL>CYGPKG_UITRON_TASKS_CREATE_DELETE</LITERAL>
with some restrictions:</PARA>
<PROGRAMLISTING>ER <FUNCTION>cre_tsk</FUNCTION>( 
  ID <EMPHASIS>tskid,</EMPHASIS>
  T_CTSK *<EMPHASIS>pk_ctsk</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>del_tsk</FUNCTION>( 
  ID <EMPHASIS>tskid</EMPHASIS> )</PROGRAMLISTING>
<PARA>These functions are restricted as follows:</PARA>
<PARA>Because of the static initialization facilities provided for
system objects, a task is allocated stack space statically in the
configuration. So while tasks can be created and deleted, the same
stack space is used for that task (task ID number) each time. Thus
the stack size (pk_ctsk-&gt;stksz) requested in <FUNCTION>cre_tsk()</FUNCTION> is
checked for being less than that which was statically allocated,
and otherwise ignored. This ensures that the new task will have
enough stack to run. For this reason <FUNCTION>del_tsk()</FUNCTION> does
not in any sense free the memory that was in use for the task's
stack. </PARA>
<PARA>The task attributes (pk_ctsk-&gt;tskatr) are
ignored; current versions of <EMPHASIS>eCos</EMPHASIS> do not need
to know whether a task is written in assembler or C/C&plus;&plus; so
long as the procedure call standard appropriate to the CPU is followed.</PARA>
<PARA>Extended information (pk_ctsk-&gt;exinf) is
	  ignored.</PARA>
<SECT2>
<TITLE>Error checking</TITLE>
<PARA>For all these calls, an invalid task id (tskid) (less than
1 or greater than the number of configured tasks) only returns E_ID
when bad params return errors (
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
is enabled, see above).</PARA>
<PARA>Similarly, the following conditions are only checked for,
and only return errors if 
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
is enabled:</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>pk_crtk in 
<FUNCTION>cre_tsk()</FUNCTION>
 is a valid pointer, otherwise return E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>ter_tsk()</FUNCTION>
 or 
<FUNCTION>rel_wai()</FUNCTION>
 on the calling task returns E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA>the CPU is not locked already in 
<FUNCTION>dis_dsp()</FUNCTION>
 and 
<FUNCTION>ena_dsp()</FUNCTION>
; returns E_CTX</PARA>
</LISTITEM>
<LISTITEM>
<PARA>priority level in 
<FUNCTION>chg_pri()</FUNCTION>
 and 
<FUNCTION>rot_rdq()</FUNCTION>
 is checked for validity, E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>return value pointer in 
<FUNCTION>get_tid()</FUNCTION>
 and 
<FUNCTION>ref_tsk()</FUNCTION>
 is a valid pointer, or E_PAR</PARA>
</LISTITEM>
</ITEMIZEDLIST>
<PARA>The following conditions are checked for, and return
	    error codes if appropriate, regardless of the setting of
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
:</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>When create and delete functions 
<FUNCTION>cre_tsk()</FUNCTION>
 and 
<FUNCTION>del_tsk()</FUNCTION>
 are supported, all calls which use a valid task ID number check
that the task exists; if not, E_NOEXS is returned</PARA>
</LISTITEM>
<LISTITEM>
<PARA>When supported, 
<FUNCTION>cre_tsk()</FUNCTION>
: the task must not already exist; otherwise E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA>When supported, 
<FUNCTION>cre_tsk()</FUNCTION>
: the requested stack size must not be larger than that statically
configured for the task; see the configuration options
&ldquo;Static initializers&rdquo;, and &ldquo;Default stack size&rdquo;.
Else E_NOMEM</PARA>
</LISTITEM>
<LISTITEM>
<PARA>When supported, 
<FUNCTION>del_tsk()</FUNCTION>
: the underlying 
<EMPHASIS>eCos</EMPHASIS>
 thread must not be running - this would imply either a bug or some
program bypassing the 
&micro;ITRON compatibility layer and manipulating the thread directly.
E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>sta_tsk()</FUNCTION>
: the task must be dormant, else E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>ter_tsk()</FUNCTION>
: the task must not be dormant, else E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>chg_pri()</FUNCTION>
: the task must not be dormant, else E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>rel_wai()</FUNCTION>
: the task must be in 
<varname>WAIT</varname> or <varname>WAIT-SUSPEND</varname>
 state, else E_OBJ</PARA>
</LISTITEM>
</ITEMIZEDLIST>
</SECT2>
</SECT1>
<SECT1 id="compat-uitron-task-dependent-synch-functions">
<TITLE><!-- <index></index> -->Task-Dependent Synchronization Functions</TITLE>
<PARA>These functions are fully supported in this release: </PARA>
<PROGRAMLISTING>ER <FUNCTION>sus_tsk</FUNCTION>( 
    ID <EMPHASIS>tskid</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>rsm_tsk</FUNCTION>( 
    ID <EMPHASIS>tskid</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>frsm_tsk</FUNCTION>( 
    ID <EMPHASIS>tskid</EMPHASIS> )</programlisting>
<programlisting>
ER <FUNCTION>slp_tsk</FUNCTION>( void )</programlisting>
	<programlisting>
ER <FUNCTION>tslp_tsk</FUNCTION>( 
    TMO <EMPHASIS>tmout</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>wup_tsk</FUNCTION>( 
    ID <EMPHASIS>tskid</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>can_wup</FUNCTION>( 
    INT *<EMPHASIS>p_wupcnt,</EMPHASIS>    ID <EMPHASIS>tskid</EMPHASIS> )</PROGRAMLISTING>
<SECT2>
<TITLE>Error checking</TITLE>
<PARA>The following conditions are only checked for, and only return
errors if 
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
is enabled (see the configuration option &ldquo;Return Error Codes for Bad
Params&rdquo;):</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>invalid tskid; less than 1 or greater than 
<LITERAL>CYGNUM_UITRON_TASKS</LITERAL>
returns E_ID</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>wup_tsk()</FUNCTION>
, 
<FUNCTION>sus_tsk()</FUNCTION>
, 
<FUNCTION>rsm_tsk()</FUNCTION>
, 
<FUNCTION>frsm_tsk()</FUNCTION>
 on the calling task returns E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA>dispatching is enabled in 
<FUNCTION>tslp_tsk()</FUNCTION>
 and 
<FUNCTION>slp_tsk()</FUNCTION>
, or E_CTX</PARA>
</LISTITEM>
<LISTITEM>
<PARA>tmout must be positive, otherwise E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>return value pointer in 
<FUNCTION>can_wup()</FUNCTION>
 is a valid pointer, or E_PAR</PARA>
</LISTITEM>
</ITEMIZEDLIST>
<PARA>The following conditions are checked for, and can
	    return error codes, regardless of the setting of
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>:
</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>When create and delete functions 
<FUNCTION>cre_tsk()</FUNCTION>
 and 
<FUNCTION>del_tsk()</FUNCTION>
 are supported, all calls which use a valid task ID number check
that the task exists; if not, E_NOEXS is returned</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>sus_tsk()</FUNCTION>
: the task must not be dormant, else E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>frsm/rsm_tsk()</FUNCTION>
: the task must be suspended, else E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>tslp/slp_tsk()</FUNCTION>
: return codes E_TMOUT, E_RLWAI and E_DLT
are returned depending on the reason for terminating the sleep</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>wup_tsk()</FUNCTION>
 and 
<FUNCTION>can_wup()</FUNCTION>
: the task must not be dormant, or E_OBJ is returned</PARA>
</LISTITEM>
</ITEMIZEDLIST>
</SECT2>
</SECT1>
<SECT1 id="compat-uitron-sync-and-comm-functions">
<TITLE><!-- <index></index> -->	  Synchronization and Communication Functions</TITLE>
<PARA>These functions are fully supported in this release: </PARA>
<PROGRAMLISTING>ER <FUNCTION>sig_sem</FUNCTION>( 
    ID <EMPHASIS>semid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>wai_sem</FUNCTION>( 
    ID <EMPHASIS>semid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>preq_sem</FUNCTION>( 
    ID <EMPHASIS>semid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>twai_sem</FUNCTION>( 
    ID <EMPHASIS>semid,</EMPHASIS>    TMO <EMPHASIS>tmout</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>ref_sem</FUNCTION>( 
    T_RSEM *<EMPHASIS>pk_rsem ,</EMPHASIS>    ID <EMPHASIS>semid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>set_flg</FUNCTION>( 
    ID <EMPHASIS>flgid,</EMPHASIS>    UINT <EMPHASIS>setptn</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>clr_flg</FUNCTION>( 
    ID <EMPHASIS>flgid,</EMPHASIS>    UINT <EMPHASIS>clrptn</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>wai_flg</FUNCTION>( 
    UINT *<EMPHASIS>p_flgptn,</EMPHASIS>    ID <EMPHASIS>flgid ,</EMPHASIS>
    UINT <EMPHASIS>waiptn ,</EMPHASIS>    UINT <EMPHASIS>wfmode</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>pol_flg</FUNCTION>( 
    UINT *<EMPHASIS>p_flgptn,</EMPHASIS>    ID <EMPHASIS>flgid ,</EMPHASIS>
    UINT <EMPHASIS>waiptn ,</EMPHASIS>    UINT <EMPHASIS>wfmode</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>twai_flg</FUNCTION>( 
    UINT *<EMPHASIS>p_flgptn</EMPHASIS>    ID <EMPHASIS>flgid ,</EMPHASIS>
    UINT <EMPHASIS>waiptn ,</EMPHASIS>    UINT <EMPHASIS>wfmode,</EMPHASIS>    TMO <EMPHASIS>tmout</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>ref_flg</FUNCTION>( 
    T_RFLG *<EMPHASIS>pk_rflg,</EMPHASIS>    ID <EMPHASIS>flgid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>snd_msg</FUNCTION>( 
    ID <EMPHASIS>mbxid,</EMPHASIS>    T_MSG <EMPHASIS>*pk_msg</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>rcv_msg</FUNCTION>( 
    T_MSG **<EMPHASIS>ppk_msg,</EMPHASIS>    ID <EMPHASIS>mbxid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>prcv_msg</FUNCTION>( 
    T_MSG **<EMPHASIS>ppk_msg,</EMPHASIS>    ID <EMPHASIS>mbxid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>trcv_msg</FUNCTION>( 
    T_MSG **<EMPHASIS>ppk_msg,</EMPHASIS>    ID <EMPHASIS>mbxid ,</EMPHASIS>    TMO <EMPHASIS>tmout</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>ref_mbx</FUNCTION>( 
    T_RMBX *<EMPHASIS>pk_rmbx,</EMPHASIS>    ID <EMPHASIS>mbxid</EMPHASIS> )</PROGRAMLISTING>
<PARA>The following functions are supported in this release (with
some restrictions) if enabled with the appropriate configuration
option for the object type (for example 
<LITERAL>CYGPKG_UITRON_SEMAS_CREATE_DELETE</LITERAL>):
</PARA>
<PROGRAMLISTING>ER <FUNCTION>cre_sem</FUNCTION>( 
    ID <EMPHASIS>semid,</EMPHASIS>    T_CSEM *<EMPHASIS>pk_csem</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>del_sem</FUNCTION>( 
    ID <EMPHASIS>semid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>cre_flg</FUNCTION>( 
    ID <EMPHASIS>flgid,</EMPHASIS>    T_CFLG *<EMPHASIS>pk_cflg</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>del_flg</FUNCTION>( 
    ID <EMPHASIS>flgid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>cre_mbx</FUNCTION>( 
    ID <EMPHASIS>mbxid,</EMPHASIS>    T_CMBX *<EMPHASIS>pk_cmbx</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>del_mbx</FUNCTION>( 
    ID <EMPHASIS>mbxid</EMPHASIS> )</PROGRAMLISTING>
<PARA>In general the queueing order when waiting on a synchronization
object depends on the underlying kernel configuration. The multi-level
queue scheduler is required for strict &micro;ITRON
conformance and it queues tasks in FIFO order, so requests to create
an object with priority queueing of tasks (<literal>pk_cxxx-&gt;xxxatr = TA_TPRI</literal>)
are rejected with E_RSATR. Additional undefined bits in
the attributes fields must be zero. </PARA>
<PARA>In general, extended information (pk_cxxx-&gt;exinf)
is ignored. </PARA>
<PARA>For semaphores, the initial semaphore count (pk_csem-&gt;isemcnt)
is supported; the new semaphore's count is set. The maximum
count is not supported, and is not in fact defined in type pk_csem. </PARA>
<PARA>For flags, multiple tasks are allowed to wait. Because single
task waiting is a subset of this, the W bit (TA_WMUL) of
the flag attributes is ignored; all other bits must be zero. The
initial flag value is supported. </PARA>
<PARA>For mailboxes, the buffer count is defined statically by kernel
configuration option 
<LITERAL>CYGNUM_KERNEL_SYNCH_MBOX_QUEUE_SIZE</LITERAL>;
therefore the buffer count field is not supported and is not in
fact defined in type pk_cmbx. Queueing of messages is FIFO
ordered only, so TA_MPRI (in pk_cmbx-&gt;mbxatr)
is not supported. </PARA>
<SECT2>
<TITLE>Error checking</TITLE>
<PARA>The following conditions are only checked for, and only return
errors if 
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
is enabled:</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>invalid object id; less than 1 or greater than 
<LITERAL>CYGNUM_UITRON_TASKS/SEMAS/MBOXES</LITERAL>
as appropriate returns E_ID</PARA>
</LISTITEM>
<LISTITEM>
<PARA>dispatching is enabled in any call which can sleep, or
E_CTX</PARA>
</LISTITEM>
<LISTITEM>
<PARA>tmout must be positive, otherwise E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>pk_cxxx pointers in 
<FUNCTION>cre_xxx()</FUNCTION>
 must be valid pointers, or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>return value pointer in 
<FUNCTION>ref_xxx()</FUNCTION>
 is valid pointer, or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>flag wait pattern must be non-zero, and mode must be valid,
or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>return value pointer in flag wait calls is a valid pointer,
or E_PAR</PARA>
</LISTITEM>
</ITEMIZEDLIST>
<PARA>The following conditions are checked for, and can return error
codes, regardless of the setting of
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
:</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>When create and delete functions 
<FUNCTION>cre_xxx()</FUNCTION>
 and 
<FUNCTION>del_xxx()</FUNCTION>
 are supported, all calls which use a valid object ID number check
that the object exists. If not, E_NOEXS is returned.</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In create functions 
<FUNCTION>cre_xxx()</FUNCTION>
, when supported, if the object already exists, then E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In any call which can sleep, such as 
<FUNCTION>twai_sem()</FUNCTION>
: return codes E_TMOUT, E_RLWAI, E_DLT
or of course E_OK are returned depending on the reason
for terminating the sleep</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In polling functions such as 
<FUNCTION>preq_sem()</FUNCTION>
return codes E_TMOUT or E_OK are returned depending
on the state of the synchronization object</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In creation functions, the attributes must be compatible
with the selected underlying kernel configuration: in 
<FUNCTION>cre_sem()</FUNCTION>
 <literal>pk_csem-&gt;sematr</literal>
 must be equal to 
<literal>TA_TFIFO</literal>
 else E_RSATR.</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In 
<FUNCTION>cre_flg()</FUNCTION>
 <literal>pk_cflg-&gt;flgatr</literal>
 must be either 
<varname>TA_WMUL</varname>
 or 
<varname>TA_WSGL</varname>
 else <varname>E_RSATR</varname>.</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In 
<FUNCTION>cre_mbx()</FUNCTION>
 
<LITERAL>pk_cmbx-&gt;mbxatr</LITERAL>
 must be 
<LITERAL>TA_TFIFO &plus; TA_MFIFO</LITERAL>
 else E_RSATR.</PARA>
</LISTITEM>
</ITEMIZEDLIST>
</SECT2>
</SECT1>
<SECT1 id="compat-uitron-extended-sync-comm-functions">
<TITLE><!-- <index></index> -->Extended Synchronization and Communication Functions</TITLE>
<PARA>None of these functions are supported in this release. </PARA>
</SECT1>
<SECT1 id="compat-uitron-interrupt-management-functions">
<TITLE><!-- <index></index> -->Interrupt management functions</TITLE>
<PARA>These functions are fully supported in this release:</PARA>
<PROGRAMLISTING>void	<FUNCTION> ret_int</FUNCTION>( void )
</programlisting>
<programlisting>
ER <FUNCTION>loc_cpu</FUNCTION>( void )
</programlisting>
<programlisting>
ER <FUNCTION>unl_cpu</FUNCTION>( void )
</programlisting>
<programlisting>
ER <FUNCTION>dis_int</FUNCTION>( 
    UINT <EMPHASIS>eintno</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>ena_int</FUNCTION>( 
    UINT <EMPHASIS>eintno</EMPHASIS> )
</programlisting>
<programlisting>
void	<FUNCTION>ret_wup</FUNCTION>( 
    ID <EMPHASIS>tskid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>iwup_tsk</FUNCTION>( 
    ID <EMPHASIS>tskid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>isig_sem</FUNCTION>( 
    ID <EMPHASIS>semid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>iset_flg</FUNCTION>( 
    ID <EMPHASIS>flgid ,</EMPHASIS>
    UID<EMPHASIS> setptn</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>isend_msg</FUNCTION>( 
    ID <EMPHASIS>mbxid ,</EMPHASIS>
    T_MSG<EMPHASIS> *pk_msg</EMPHASIS> )</PROGRAMLISTING>
<PARA>Note that <FUNCTION>ret_int()</FUNCTION> and
the <FUNCTION>ret_wup()</FUNCTION> are  implemented
as macros, containing a &ldquo;return&rdquo; statement.</PARA>
<PARA>Also note that <FUNCTION>ret_wup()</FUNCTION> and
the <FUNCTION>ixxx_yyy()</FUNCTION> style functions
will only work when called from an ISR whose associated DSR is <FUNCTION>cyg_uitron_dsr()</FUNCTION>,
as specified in include file <filename>&lt;cyg/compat/uitron/uit_ifnc.h&gt;</filename>,
which defines the <FUNCTION>ixxx_yyy()</FUNCTION> style
functions also.</PARA>
<PARA>If you are writing interrupt handlers more in the
<EMPHASIS>eCos</EMPHASIS> style, with separate ISR and DSR routines both of
your own devising, do not use these special functions from a DSR: use plain
<FUNCTION>xxx_yyy()</FUNCTION> style functions (with no &lsquo;i&rsquo; prefix)
instead, and do not call any &micro;ITRON functions from the ISR at
all.</PARA>
<PARA>The following functions are not supported in this release: </PARA>
<PROGRAMLISTING>ER <FUNCTION>def_int</FUNCTION>( 
    UINT <EMPHASIS>dintno,</EMPHASIS>
  T_DINT *<EMPHASIS>pk_dint</EMPHASIS> )</programlisting>
	<programlisting>
ER <FUNCTION>chg_iXX</FUNCTION>( 
    UINT <EMPHASIS>iXXXX</EMPHASIS> )
  </programlisting>
	<programlisting>
ER <FUNCTION>ref_iXX</FUNCTION>( 
    UINT * <EMPHASIS>p_iXXXX</EMPHASIS> )</PROGRAMLISTING>
<PARA>These unsupported functions are all Level C (CPU dependent).
Equivalent functionality is available via other <EMPHASIS>eCos</EMPHASIS>-specific
APIs. </PARA>
<SECT2>
<TITLE>Error checking</TITLE>
<PARA>The following conditions are only checked for, and only return
errors if 
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
is enabled:</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA><FUNCTION>loc/unl_cpu()</FUNCTION>
: these must only be called in a 
&micro;ITRON task context, else E_CTX.</PARA>
</LISTITEM>
<LISTITEM>
<PARA><FUNCTION>dis/ena_int()</FUNCTION>
: the interrupt number must be in range as specified by the platform
HAL in qustion, else E_PAR.</PARA>
</LISTITEM>
</ITEMIZEDLIST>
</SECT2>
</SECT1>
<SECT1 id="compat-uitron-memory-pool-mgmt-functions">
<TITLE><!-- <index></index> -->	  Memory pool Management Functions</TITLE>
<PARA>These functions are fully supported in this release: </PARA>
<PROGRAMLISTING>ER <FUNCTION>get_blf</FUNCTION>( 
    VP *<EMPHASIS>p_blf,</EMPHASIS>    ID <EMPHASIS>mpfid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>pget_blf</FUNCTION>( 
    VP *<EMPHASIS>p_blf,</EMPHASIS>    ID <EMPHASIS>mpfid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>tget_blf</FUNCTION>( 
    VP *<EMPHASIS>p_blf,</EMPHASIS>    ID <EMPHASIS>mpfid,</EMPHASIS>    TMO <EMPHASIS>tmout</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>rel_blf</FUNCTION>( 
    ID <EMPHASIS>mpfid,</EMPHASIS>    VP <EMPHASIS>blf</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>ref_mpf</FUNCTION>( 
    T_RMPF *<EMPHASIS>pk_rmpf,</EMPHASIS>    ID <EMPHASIS>mpfid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>get_blk</FUNCTION>( 
    VP *<EMPHASIS>p_blk,</EMPHASIS>    ID <EMPHASIS>mplid,</EMPHASIS>    INT <EMPHASIS>blksz</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>pget_blk</FUNCTION>( 
    VP *<EMPHASIS>p_blk,</EMPHASIS>    ID <EMPHASIS>mplid,</EMPHASIS>    INT <EMPHASIS>blksz</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>tget_blk</FUNCTION>( 
    VP *<EMPHASIS>p_blk,</EMPHASIS>    ID <EMPHASIS>mplid,</EMPHASIS>    INT <EMPHASIS>blksz,</EMPHASIS>    TMO <EMPHASIS>tmout</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>rel_blk</FUNCTION>( 
    ID <EMPHASIS>mplid,</EMPHASIS>    VP <EMPHASIS>blk</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>ref_mpl</FUNCTION>( 
    T_RMPL *<EMPHASIS>pk_rmpl,</EMPHASIS>    ID <EMPHASIS>mplid )
</EMPHASIS></programlisting>

<PARA>Note that of the memory provided for a particular pool to
manage in the static initialization of the memory pool objects,
some memory will be used to manage the pool itself. Therefore the
number of blocks * the blocksize will be less than the total
memory size. </PARA>
<PARA>The following functions are supported in this release, when
enabled with 
<LITERAL>CYGPKG_UITRON_MEMPOOLVAR_CREATE_DELETE</LITERAL>
or 
<LITERAL>CYGPKG_UITRON_MEMPOOLFIXED_CREATE_DELETE</LITERAL>
as appropriate, with some restrictions: </PARA>
<PROGRAMLISTING>ER <FUNCTION>cre_mpl</FUNCTION>( 
    ID <EMPHASIS>mplid,</EMPHASIS>    T_CMPL *<EMPHASIS>pk_cmpl</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>del_mpl</FUNCTION>( 
    ID <EMPHASIS>mplid</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>cre_mpf</FUNCTION>( 
    ID <EMPHASIS>mpfid,</EMPHASIS>    T_CMPF *<EMPHASIS>pk_cmpf</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>del_mpf</FUNCTION>( 
    ID <EMPHASIS>mpfid</EMPHASIS> )</PROGRAMLISTING>
<PARA>Because of the static initialization facilities provided for
system objects, a memory pool is allocated a region of memory to
manage statically in the configuration. So while memory pools can
be created and deleted, the same area of memory is used for that
memory pool (memory pool ID number) each time. The requested variable pool
size (pk_cmpl-&gt;mplsz) or the number of fixed-size
blocks (pk_cmpf-&gt;mpfcnt) times the block size
(pk_cmpf-&gt;blfsz) are checked for fitting within
the statically allocated memory area, so if a create call succeeds,
the resulting pool will be at least as large as that requested.
For this reason <FUNCTION>del_mpl()</FUNCTION> and <FUNCTION>del_mpf()</FUNCTION> do
not in any sense free the memory that was managed by the deleted
pool for use by other pools; it may only be managed by a pool of
the same object id. </PARA>
<PARA>For both fixed and variable memory pools, the queueing order
when waiting on a synchronization object depends on the underlying
kernel configuration. The multi-level queue scheduler is required
for strict &micro;ITRON conformance and
it queues tasks in FIFO order, so requests to create an object with
priority queueing of tasks (pk_cxxx-&gt;xxxatr = TA_TPRI)
are rejected with E_RSATR. Additional undefined bits in
the attributes fields must be zero. </PARA>
<PARA>In general, extended information (pk_cxxx-&gt;exinf)
is ignored. </PARA>
<SECT2>
<TITLE>Error checking</TITLE>
<PARA>The following conditions are only checked for, and only return
errors if 
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
is enabled:</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>invalid object id; less than 1 or greater than 
<LITERAL>CYGNUM_UITRON_MEMPOOLVAR/MEMPOOLFIXED</LITERAL>
as appropriate returns E_ID</PARA>
</LISTITEM>
<LISTITEM>
<PARA>dispatching is enabled in any call which can sleep, or
E_CTX</PARA>
</LISTITEM>
<LISTITEM>
<PARA>tmout must be positive, otherwise E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>pk_cxxx pointers in 
<FUNCTION>cre_xxx()</FUNCTION>
 must be valid pointers, or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>return value pointer in 
<FUNCTION>ref_xxx()</FUNCTION>
 is a valid pointer, or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>return value pointers in get block routines is a valid
pointer, or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>blocksize request in get variable block routines is greater
than zero, or E_PAR</PARA>
</LISTITEM>
</ITEMIZEDLIST>
<PARA>The following conditions are checked for, and can return error
codes, regardless of the setting of 
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>:
</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>When create and delete functions 
<FUNCTION>cre_xxx()</FUNCTION>
 and 
<FUNCTION>del_xxx()</FUNCTION>
 are supported, all calls which use a valid object ID number check
that the object exists. If not, E_NOEXS is returned.</PARA>
</LISTITEM>
<LISTITEM>
<PARA>When create functions 
<FUNCTION>cre_xxx()</FUNCTION>
 are supported, if the object already exists, then E_OBJ</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In any call which can sleep, such as 
<FUNCTION>get_blk()</FUNCTION>
: return codes E_TMOUT, E_RLWAI, E_DLT
or of course E_OK are returned depending on the reason
for terminating the sleep</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In polling functions such as 
<FUNCTION>pget_blk()</FUNCTION>
return codes E_TMOUT or E_OK are returned depending
on the state of the synchronization object</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In creation functions, the attributes must be compatible
with the selected underlying kernel configuration: in 
<FUNCTION>cre_mpl()</FUNCTION>
 
<LITERAL>pk_cmpl-&gt;mplatr</LITERAL>
 must be equal to 
<LITERAL>TA_TFIFO</LITERAL>
 else E_RSATR.</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In 
<FUNCTION>cre_mpf()</FUNCTION>
 
<LITERAL>pk_cmpf-&gt;mpfatr</LITERAL>
 must be equal to 
<LITERAL>TA_TFIFO</LITERAL>
 else E_RSATR.</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In creation functions, the requested size of the memory
pool must not be larger than that statically configured for the
pool else E_RSATR; see the configuration option
&ldquo;Option: Static initializers&rdquo;.
 In 
<FUNCTION>cre_mpl()</FUNCTION>
 
<LITERAL>pk_cmpl-&gt;mplsz</LITERAL>
 is the field of interest</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In 
<FUNCTION>cre_mpf()</FUNCTION>
 the product of 
<LITERAL>pk_cmpf-&gt;blfsz</LITERAL>
 and 
<LITERAL>pk_cmpf-&gt;mpfcnt</LITERAL>
 must be smaller than the memory statically configured for the pool
else E_RSATR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>In functions which return memory to the pool 
<FUNCTION>rel_blk()</FUNCTION>
 and 
<FUNCTION>rel_blf()</FUNCTION>
, if the free fails, for example because the memory did not come
from that pool originally, then E_PAR is returned</PARA>
</LISTITEM>
</ITEMIZEDLIST>
</SECT2>
</SECT1>
<SECT1 id="compat-uitron-time-mgmt-functions">
<TITLE><!-- <index></index> -->Time Management Functions</TITLE>
<PARA>These functions are fully supported in this release: </PARA>
<PROGRAMLISTING>ER <FUNCTION>set_tim</FUNCTION>( 
    SYSTIME *<EMPHASIS>pk_tim</EMPHASIS> )</PROGRAMLISTING>
<CAUTION>
<PARA>	    Setting the time may cause erroneous operation of the
	    kernel, for example a task performing a wait with a
	    time-out may never awaken.</PARA>
</CAUTION>
<PROGRAMLISTING>ER <FUNCTION>get_tim</FUNCTION>( 
    SYSTIME *<EMPHASIS>pk_tim</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>dly_tsk</FUNCTION>( 
    DLYTIME <EMPHASIS>dlytim</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>def_cyc</FUNCTION>( 
    HNO <EMPHASIS>cycno,</EMPHASIS>    T_DCYC *<EMPHASIS>pk_dcyc</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>act_cyc</FUNCTION>( 
    HNO <EMPHASIS>cycno,</EMPHASIS>    UINT <EMPHASIS>cycact</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>ref_cyc</FUNCTION>( 
    T_RCYC *<EMPHASIS>pk_rcyc,</EMPHASIS>    HNO <EMPHASIS>cycno</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>def_alm</FUNCTION>( 
    HNO <EMPHASIS>almno,</EMPHASIS>    T_DALM *<EMPHASIS>pk_dalm</EMPHASIS> )
</programlisting>
<programlisting>
ER <FUNCTION>ref_alm</FUNCTION>( 
    T_RALM *<EMPHASIS>pk_ralm,</EMPHASIS>    HNO <EMPHASIS>almno</EMPHASIS> )
</programlisting>
<programlisting>
void <FUNCTION>ret_tmr</FUNCTION>( void )</programlisting>
	<sect2>
	  <title>Error checking</title>
<PARA>The following conditions are only checked for, and only return
errors if 
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
is enabled:</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>invalid handler number; less than 1 or greater than 
<LITERAL>CYGNUM_UITRON_CYCLICS/ALARMS</LITERAL>
as appropriate, or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>dispatching is enabled in 
<FUNCTION>dly_tsk()</FUNCTION>
, or E_CTX</PARA>
</LISTITEM>
<LISTITEM>
<PARA>dlytim must be positive or zero, otherwise E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>return value pointer in 
<FUNCTION>ref_xxx()</FUNCTION>
 is a valid pointer, or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>params within pk_dalm and pk_dcyc must
be valid, or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>cycact in 
<FUNCTION>act_cyc()</FUNCTION>
 must be valid, or E_PAR</PARA>
</LISTITEM>
<LISTITEM>
<PARA>handler must be defined in 
<FUNCTION>ref_xxx()</FUNCTION>
 and 
<FUNCTION>act_cyc()</FUNCTION>
, or E_NOEXS</PARA>
</LISTITEM>
<LISTITEM>
<PARA>parameter pointer must be a good pointer in 
<FUNCTION>get_tim()</FUNCTION>
 and 
<FUNCTION>set_tim()</FUNCTION>
, otherwise E_PAR is returned</PARA>
</LISTITEM>
</ITEMIZEDLIST>
<PARA>The following conditions are checked for, and can return
	  error codes, regardless of the setting of
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
:</PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA><FUNCTION>dly_tsk()</FUNCTION>
: return code E_RLWAI is returned depending on the reason
for terminating the sleep</PARA>
</LISTITEM>
</ITEMIZEDLIST>
</sect2>
</SECT1>
<SECT1 id="compat-uitron-system-mgmt-functions">
<TITLE><!-- <index></index> -->	  System Management Functions</TITLE>
<PARA>These functions are fully supported in this release:
	</PARA>
<PROGRAMLISTING>ER <FUNCTION>get_ver</FUNCTION>( 
    T_VER *<EMPHASIS>pk_ver</EMPHASIS> )
</PROGRAMLISTING>
<PROGRAMLISTING>ER <FUNCTION>ref_sys</FUNCTION>( 
    T_RSYS *<EMPHASIS>pk_rsys</EMPHASIS> )
</PROGRAMLISTING>
<PROGRAMLISTING>ER <FUNCTION>ref_cfg</FUNCTION>( 
    T_RCFG *<EMPHASIS>pk_rcfg</EMPHASIS> )
</PROGRAMLISTING>
<PARA>Note that the information returned by each of these calls
may be configured to match the user's own versioning system,
and the values supplied by the default configuration may be inappropriate. </PARA>
<PARA>These functions are not supported in this release: </PARA>
<PROGRAMLISTING>ER <FUNCTION>def_svc</FUNCTION>( 
    FN <EMPHASIS>s_fncd,</EMPHASIS>
    T_DSVC *<EMPHASIS>pk_dsvc</EMPHASIS> )
</PROGRAMLISTING>
<PROGRAMLISTING>ER <FUNCTION>def_exc</FUNCTION>( 
    UINT <EMPHASIS>exckind,</EMPHASIS>
    T_DEXC *<EMPHASIS>pk_dexc</EMPHASIS> )
</PROGRAMLISTING>
<SECT2>
<TITLE>Error checking</TITLE>
<PARA>The following conditions are only checked for, and
	    only return errors if
	    
<LITERAL>CYGSEM_UITRON_BAD_PARAMS_RETURN_ERRORS</LITERAL>
 is enabled: </PARA>
<ITEMIZEDLIST>
<LISTITEM>
<PARA>return value pointer in all calls is a valid
	      pointer, or E_PAR</PARA>
</LISTITEM>
</ITEMIZEDLIST>
</SECT2>
</SECT1>
<SECT1 id="compat-uitron-network-support-functions">
<TITLE><!-- <index></index> -->	  Network Support Functions</TITLE>
<PARA>None of these functions are supported in this release.
	</PARA>
</SECT1>
<SECT1 id="compat-uitron-configuration-faq">
<TITLE><!-- <index></index> -->&micro;ITRON Configuration FAQ</TITLE>
<PARA><EMPHASIS>Q: How are &micro;ITRON objects created?</EMPHASIS>
</PARA>
<PARA>
For each type of uITRON object (tasks, semaphores, flags, mboxes, mpf, mpl)
these two quantities are controlled by configuration:
</PARA>
<ITEMIZEDLIST>
<LISTITEM><PARA>
The <EMPHASIS>maximum</EMPHASIS> number of this type of object.
</PARA></LISTITEM>
<LISTITEM><PARA>
The number of these objects which exist <EMPHASIS>initially</EMPHASIS>.
</PARA></LISTITEM>
</ITEMIZEDLIST>
<PARA>
This is assuming that for the relevant object type,
<EMPHASIS>create</EMPHASIS> and <EMPHASIS>delete</EMPHASIS>
operations are enabled; enabled is the default.  For example, the option
<LITERAL>CYGPKG_UITRON_MBOXES_CREATE_DELETE</LITERAL>
controls whether the functions
<FUNCTION>cre_mbx()</FUNCTION>
and
<FUNCTION>del_mbx()</FUNCTION>
exist in the API.  If not, then the maximum number of
mboxes is the same as the initial number of mboxes, and so on for all
&micro;ITRON object types.
</PARA>
<PARA>
Mboxes have no initialization, so there are only a few, simple
configuration options:
</PARA>
<ITEMIZEDLIST>
<LISTITEM><PARA>
<LITERAL>CYGNUM_UITRON_MBOXES</LITERAL>
is the total number of mboxes that you can have in the
system.  By default this is 4, so you can use mboxes 1,2,3 and 4.  You
cannot create mboxes outside this range; trying to
<FUNCTION>cre_mbx(5,...)</FUNCTION>
will return an error.
</PARA></LISTITEM>
<LISTITEM><PARA>
<LITERAL>CYGNUM_UITRON_MBOXES_INITIALLY</LITERAL>
is the number of mboxes created
automatically for you, during startup.  By default this is 4, so all 4
mboxes exist already, and an attempt to create one of these
eg. <FUNCTION>cre_mbx(3,...)</FUNCTION>
will return an error because the mbox in quesion already
exists.  You can delete a pre-existing mbox, and then re-create it.
</PARA></LISTITEM>
</ITEMIZEDLIST>
<PARA>
If you change 
<LITERAL>CYGNUM_UITRON_MBOXES_INITIALLY</LITERAL>,
for example to 0, no mboxes
are created automatically for you during startup.  Any attempt to use an
mbox without creating it will return E_NOEXS because the mbox does not
exist.  You can create an mbox, say <FUNCTION>cre_mbx(3,...)</FUNCTION>
and then use it, say
<FUNCTION>snd_msg(3,&amp;foo)</FUNCTION>, and all will be well.
</PARA>
<PARA><EMPHASIS>Q: How are &micro;ITRON objects initialized?</EMPHASIS>
</PARA>
<PARA>
Some object types have optional initialization.  Semaphores are an
example.  You could have 
<LITERAL>CYGNUM_UITRON_SEMAS</LITERAL>=10 and
<LITERAL>CYGNUM_UITRON_SEMAS_INITIALLY</LITERAL>=5
which means you can use semaphores 1-5
straight off, but you must create semaphores 6-10 before you can use them.
If you decide not to initialize semaphores, semaphores 1-5 will have an
initial count of zero.  If you decide to initialize them, you must supply
a dummy initializer for semaphores 6-10 also.  For example,
in terms of the configuration output in
<filename>pkgconf/uitron.h</filename>:
</PARA>
<PROGRAMLISTING>
   #define CYGDAT_UITRON_SEMA_INITIALIZERS \
        CYG_UIT_SEMA(  1 ),     \
        CYG_UIT_SEMA(  0 ),     \
        CYG_UIT_SEMA(  0 ),     \
        CYG_UIT_SEMA( 99 ),     \
        CYG_UIT_SEMA(  1 ),     \
        CYG_UIT_SEMA_NOEXS,     \
        CYG_UIT_SEMA_NOEXS,     \
        CYG_UIT_SEMA_NOEXS,     \
        CYG_UIT_SEMA_NOEXS,     \
        CYG_UIT_SEMA_NOEXS
</PROGRAMLISTING>
<PARA>
Semaphore 1 will have initial count 1, semaphores 2 and 3 will be zero,
number 4 will be 99 initially, 5 will be one and numbers 6 though 10 do not
exist initially.
</PARA>
<PARA>
Aside: this is how the definition of the symbol would appear in the
configuration header file <filename>pkgconf/uitron.h</filename> &mdash;
unfortunately editing such a long, multi-line definition is somewhat
cumbersome in the GUI config tool in current releases.  The macros
<LITERAL>CYG_UIT_SEMA()</LITERAL>
&mdash; to create a semaphore initializer &mdash; and
<LITERAL>CYG_UIT_SEMA_NOEXS</LITERAL>
&mdash; to invoke a dummy initializer &mdash;
are provided in in the environment to help with this.  Similar macros are
provided for other object types.  The resulting #define symbol is used in
the context of a C++ array initializer, such as:
<PROGRAMLISTING>
Cyg_Counting_Semaphore2 cyg_uitron_SEMAS[ CYGNUM_UITRON_SEMAS ] = {
	CYGDAT_UITRON_SEMA_INITIALIZERS
};
</PROGRAMLISTING>
which is eventually macro-processed to give
<PROGRAMLISTING>
Cyg_Counting_Semaphore2 cyg_uitron_SEMAS[ 10 ] = {
	Cyg_Counting_Semaphore2( ( 1 ) ), 
	Cyg_Counting_Semaphore2( ( 0 ) ), 
	Cyg_Counting_Semaphore2( ( 0 ) ), 
	Cyg_Counting_Semaphore2( ( 99 ) ), 
	Cyg_Counting_Semaphore2( ( 1 ) ), 
	Cyg_Counting_Semaphore2(0), 
	Cyg_Counting_Semaphore2(0), 
	Cyg_Counting_Semaphore2(0), 
	Cyg_Counting_Semaphore2(0), 
	Cyg_Counting_Semaphore2(0), 
};
</PROGRAMLISTING>
so you can see how it is necessary to include the dummy entries in that
definition, otherwise the resulting code will not compile correctly.
</PARA>
<PARA>
If you choose 
<LITERAL>CYGNUM_UITRON_SEMAS_INITIALLY</LITERAL>=0
it is meaningless to initialize them, for they must be created and so
initialized then, before use.
</PARA>
<PARA><EMPHASIS>Q: What about &micro;ITRON tasks?</EMPHASIS>
</PARA>
<PARA>
Some object types require initialization.  Tasks are an example of this.
You must provide a task with a priority, a function to enter when the task
starts, a name (for debugging purposes), and some memory to use for the stack.
For example (again in terms of the resulting
definitions in <filename>pkgconf/uitron.h</filename>):
</PARA>
<PROGRAMLISTING>
#define CYGNUM_UITRON_TASKS 4           // valid task ids are 1,2,3,4
#define CYGNUM_UITRON_TASKS_INITIALLY 4 // they all exist at start

#define CYGDAT_UITRON_TASK_EXTERNS          	\
extern "C" void startup( unsigned int );    	\
extern "C" void worktask( unsigned int );   	\
extern "C" void lowtask( unsigned int );        \
static char stack1[ CYGNUM_UITRON_STACK_SIZE ], \
            stack2[ CYGNUM_UITRON_STACK_SIZE ], \
            stack3[ CYGNUM_UITRON_STACK_SIZE ], \
            stack4[ CYGNUM_UITRON_STACK_SIZE ];

#define CYGDAT_UITRON_TASK_INITIALIZERS \
 CYG_UIT_TASK("main task", 8, startup,  &amp;stack1, sizeof( stack1 )), \
 CYG_UIT_TASK("worker 2" , 9, worktask, &amp;stack2, sizeof( stack2 )), \
 CYG_UIT_TASK("worker 3" , 9, worktask, &amp;stack3, sizeof( stack3 )), \
 CYG_UIT_TASK("low task" ,20, lowtask,  &amp;stack4, sizeof( stack4 )), \

</PROGRAMLISTING>
<PARA>
So this example has all four tasks statically configured to exist, ready to
run, from the start of time.  The &ldquo;main task&rdquo; runs a routine
called <FUNCTION>startup()</FUNCTION> at priority 8.  Two
&ldquo;worker&rdquo; tasks run both a priority 9, and a &ldquo;low
priority&rdquo; task runs at priority 20 to do useful non-urgent background
work.
</PARA>
<screen>
Task ID | Exists at | Function | Priority | Stack   | Stack
 number |  startup  |  entry   |          | address | size
--------+-----------+----------+----------+---------+----------
   1    |    Yes    |  startup |    8     | &amp;stack1 | CYGNUM...
   2    |    Yes    | worktask |    9 	  | &amp;stack2 | CYGNUM...
   3    |    Yes    | worktask |    9 	  | &amp;stack3 | CYGNUM...
   4    |    Yes    |  lowtask |   20 	  | &amp;stack4 | CYGNUM...
--------+-----------+----------+----------+---------+----------
</screen>
<PARA><EMPHASIS>Q: How can I create &micro;ITRON tasks in the program?</EMPHASIS>
</PARA>
<PARA>
You must provide free slots in the task table in which to create new tasks,
by configuring the number of tasks existing initially to be smaller than
the total.
For a task ID which does not initially exist, it will be told what routine
to call, and what priority it is, when the task is created.  But you must
still set aside memory for the task to use for its stack, and give it a
name during initialization.  For example:
</PARA>

<PROGRAMLISTING>
#define CYGNUM_UITRON_TASKS 4           // valid task ids are 1-4
#define CYGNUM_UITRON_TASKS_INITIALLY 1 // only task #1 exists

#define CYGDAT_UITRON_TASK_EXTERNS \
extern "C" void startup( unsigned int ); \
static char stack1[ CYGNUM_UITRON_STACK_SIZE ], \
            stack2[ CYGNUM_UITRON_STACK_SIZE ], \
            stack3[ CYGNUM_UITRON_STACK_SIZE ], \
            stack4[ CYGNUM_UITRON_STACK_SIZE ];

#define CYGDAT_UITRON_TASK_INITIALIZERS \
   CYG_UIT_TASK( "main", 8, startup, &amp;stack1, sizeof( stack1 ) ), \
   CYG_UIT_TASK_NOEXS( "slave",      &amp;stack2, sizeof( stack2 ) ), \
   CYG_UIT_TASK_NOEXS( "slave2",     &amp;stack3, sizeof( stack3 ) ), \
   CYG_UIT_TASK_NOEXS( "slave3",     &amp;stack4, sizeof( stack4 ) ), \

</PROGRAMLISTING>
<PARA>
So tasks numbered 2,3 and 4 have been given their stacks during startup,
though they do not yet exist in terms of <FUNCTION>cre_tsk()</FUNCTION> and
<FUNCTION>del_tsk()</FUNCTION> so you can create tasks 2&ndash;4 at
runtime.
</PARA>
<screen>
Task ID | Exists at | Function | Priority | Stack   | Stack
 number |  startup  |  entry   |          | address | size
--------+-----------+----------+----------+---------+----------
   1    |    Yes    |  startup |    8     | &amp;stack1 | CYGNUM...
   2    |    No     |   N/A    |   N/A    | &amp;stack2 | CYGNUM...
   3    |    No     |   N/A    |   N/A    | &amp;stack3 | CYGNUM...
   4    |    No     |   N/A    |   N/A    | &amp;stack4 | CYGNUM...
--------+-----------+----------+----------+---------+----------
</screen>
<PARA>
(you must have at least one task at startup in order that the system can
 actually run; this is not so for other uITRON object types)
</PARA>
<PARA><EMPHASIS>Q: Can I have different stack sizes for &micro;ITRON tasks?</EMPHASIS>
</PARA>
<PARA>
Simply set aside different amounts of memory for each task to use for its
stack.  Going back to a typical default setting for the &micro;ITRON tasks,
the definitions in <filename>pkgconf/uitron.h</filename> might look like this:
</PARA>
<PROGRAMLISTING>
#define CYGDAT_UITRON_TASK_EXTERNS \
extern "C" void task1( unsigned int ); \
extern "C" void task2( unsigned int ); \
extern "C" void task3( unsigned int ); \
extern "C" void task4( unsigned int ); \
static char stack1[ CYGNUM_UITRON_STACK_SIZE ], \
            stack2[ CYGNUM_UITRON_STACK_SIZE ], \
            stack3[ CYGNUM_UITRON_STACK_SIZE ], \
            stack4[ CYGNUM_UITRON_STACK_SIZE ];
  
#define CYGDAT_UITRON_TASK_INITIALIZERS \
  CYG_UIT_TASK( "t1", 1, task1, &amp;stack1, CYGNUM_UITRON_STACK_SIZE ), \
  CYG_UIT_TASK( "t2", 2, task2, &amp;stack2, CYGNUM_UITRON_STACK_SIZE ), \
  CYG_UIT_TASK( "t3", 3, task3, &amp;stack3, CYGNUM_UITRON_STACK_SIZE ), \
  CYG_UIT_TASK( "t4", 4, task4, &amp;stack4, CYGNUM_UITRON_STACK_SIZE )

</PROGRAMLISTING>
<PARA>
Note that 
<LITERAL>CYGNUM_UITRON_STACK_SIZE</LITERAL>
is used to control the size of the stack
objects themselves, and to tell the system what size stack is being provided.
</PARA>
<PARA>
Suppose instead stack sizes of 2000, 1000, 800 and 800 were required:
this could be achieved by using the GUI config tool to edit these
options, or editting the <filename>.ecc</filename> file to get these
results in <filename>pkgconf/uitron.h</filename>:
</PARA>
<PROGRAMLISTING>
#define CYGDAT_UITRON_TASK_EXTERNS \
extern "C" void task1( unsigned int ); \
extern "C" void task2( unsigned int ); \
extern "C" void task3( unsigned int ); \
extern "C" void task4( unsigned int ); \
static char stack1[ 2000 ], \
            stack2[ 1000 ], \
            stack3[  800 ], \
            stack4[  800 ];
 
#define CYGDAT_UITRON_TASK_INITIALIZERS \
      CYG_UIT_TASK( "t1", 1, task1, &amp;stack1, sizeof( stack1 ) ), \
      CYG_UIT_TASK( "t2", 2, task2, &amp;stack2, sizeof( stack2 ) ), \
      CYG_UIT_TASK( "t3", 3, task3, &amp;stack3, sizeof( stack3 ) ), \
      CYG_UIT_TASK( "t4", 4, task4, &amp;stack4, sizeof( stack4 ) )
</PROGRAMLISTING>
<PARA>
Note that the sizeof() operator has been used to tell the system what size
stacks are provided, rather than quoting a number (which is difficult for
maintenance) or the symbol 
<LITERAL>CYGNUM_UITRON_STACK_SIZE</LITERAL>
(which is wrong).
</PARA>
<PARA>
We recommend using (if available in your release) the stacksize symbols
provided in the architectural HAL for your target, called
<LITERAL>CYGNUM_HAL_STACK_SIZE_TYPICAL</LITERAL>
and 
<LITERAL>CYGNUM_HAL_STACK_SIZE_MINIMUM</LITERAL>.
So a better (more portable) version of the above might be:
</PARA>
<PROGRAMLISTING>
#define CYGDAT_UITRON_TASK_EXTERNS \
extern "C" void task1( unsigned int ); \
extern "C" void task2( unsigned int ); \
extern "C" void task3( unsigned int ); \
extern "C" void task4( unsigned int ); \
static char stack1[ CYGNUM_HAL_STACK_SIZE_TYPICAL + 1200 ], \
            stack2[ CYGNUM_HAL_STACK_SIZE_TYPICAL +  200 ], \
            stack3[ CYGNUM_HAL_STACK_SIZE_TYPICAL        ], \
            stack4[ CYGNUM_HAL_STACK_SIZE_TYPICAL        ];

#define CYGDAT_UITRON_TASK_INITIALIZERS \
      CYG_UIT_TASK( "t1", 1, task1, &amp;stack1, sizeof( stack1 ) ), \
      CYG_UIT_TASK( "t2", 2, task2, &amp;stack2, sizeof( stack2 ) ), \
      CYG_UIT_TASK( "t3", 3, task3, &amp;stack3, sizeof( stack3 ) ), \
      CYG_UIT_TASK( "t4", 4, task4, &amp;stack4, sizeof( stack4 ) )
</PROGRAMLISTING>
</SECT1>
</CHAPTER>
</part>
