[sdl_omap.git] / docs / html / sdlcreatesemaphore.html

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>SDL_CreateSemaphore</TITLE
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>SDL_CreateSemaphore</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN7936"
></A
><H2
>Name</H2
>SDL_CreateSemaphore&nbsp;--&nbsp;Creates a new semaphore and assigns an initial value to it.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN7939"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN7940"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"
#include "SDL_thread.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>SDL_sem *<B
CLASS="FSFUNC"
>SDL_CreateSemaphore</B
></CODE
>(Uint32 initial_value);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7946"
></A
><H2
>Description</H2
><P
><TT
CLASS="FUNCTION"
>SDL_CreateSemaphore()</TT
> creates a new semaphore and
initializes it with the value <TT
CLASS="PARAMETER"
><I
>initial_value</I
></TT
>.
Each locking operation on the semaphore by
<A
HREF="sdlsemwait.html"
>SDL_SemWait</A
>,
<A
HREF="sdlsemtrywait.html"
>SDL_SemTryWait</A
> or
<A
HREF="sdlsemwaittimeout.html"
>SDL_SemWaitTimeout</A
>
will atomically decrement the semaphore value. The locking operation will be blocked
if the semaphore value is not positive (greater than zero). Each unlock operation by
<A
HREF="sdlsempost.html"
>SDL_SemPost</A
>
will atomically increment the semaphore value.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7955"
></A
><H2
>Return Value</H2
><P
>Returns a pointer to an initialized semaphore or
<SPAN
CLASS="RETURNVALUE"
>NULL</SPAN
> if there was an error.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7959"
></A
><H2
>Examples</H2
><P
><PRE
CLASS="PROGRAMLISTING"
>SDL_sem *my_sem;

my_sem = SDL_CreateSemaphore(INITIAL_SEM_VALUE);

if (my_sem == NULL) {
        return CREATE_SEM_FAILED;
}</PRE
></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7963"
></A
><H2
>See Also</H2
><P
><A
HREF="sdldestroysemaphore.html"
><TT
CLASS="FUNCTION"
>SDL_DestroySemaphore</TT
></A
>,
<A
HREF="sdlsemwait.html"
><TT
CLASS="FUNCTION"
>SDL_SemWait</TT
></A
>,
<A
HREF="sdlsemtrywait.html"
><TT
CLASS="FUNCTION"
>SDL_SemTryWait</TT
></A
>,
<A
HREF="sdlsemwaittimeout.html"
><TT
CLASS="FUNCTION"
>SDL_SemWaitTimeout</TT
></A
>,
<A
HREF="sdlsempost.html"
><TT
CLASS="FUNCTION"
>SDL_SemPost</TT
></A
>,
<A
HREF="sdlsemvalue.html"
><TT
CLASS="FUNCTION"
>SDL_SemValue</TT
></A
></P
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>
Commit	Line	Data
e14743d1	1	<HTML
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	4	>SDL_CreateSemaphore</TITLE
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	7	CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
	8	"><LINK
	9	REL="HOME"
	10	TITLE="SDL Library Documentation"
	11	HREF="index.html"><LINK
	12	REL="UP"
	13	TITLE="Multi-threaded Programming"
	14	HREF="thread.html"><LINK
	15	REL="PREVIOUS"
	16	TITLE="SDL_mutexV"
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	18	REL="NEXT"
	19	TITLE="SDL_DestroySemaphore"
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	40	>SDL Library Documentation</TH
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	44	WIDTH="10%"
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68	><HR
69	ALIGN="LEFT"
70	WIDTH="100%"></DIV
71	><H1
72	><A
73	NAME="SDLCREATESEMAPHORE"
74	></A
75	>SDL_CreateSemaphore</H1
76	><DIV
77	CLASS="REFNAMEDIV"
78	><A
79	NAME="AEN7936"
80	></A
81	><H2
82	>Name</H2
83	>SDL_CreateSemaphore -- Creates a new semaphore and assigns an initial value to it.</DIV
84	><DIV
85	CLASS="REFSYNOPSISDIV"
86	><A
87	NAME="AEN7939"
88	></A
89	><H2
90	>Synopsis</H2
91	><DIV
92	CLASS="FUNCSYNOPSIS"
93	><A
94	NAME="AEN7940"
95	></A
96	><P
97	></P
98	><PRE
99	CLASS="FUNCSYNOPSISINFO"
100	>#include "SDL.h"
101	#include "SDL_thread.h"</PRE
102	><P
103	><CODE
104	><CODE
105	CLASS="FUNCDEF"
106	>SDL_sem *<B
107	CLASS="FSFUNC"
108	>SDL_CreateSemaphore</B
109	></CODE
110	>(Uint32 initial_value);</CODE
111	></P
112	><P
113	></P
114	></DIV
115	></DIV
116	><DIV
117	CLASS="REFSECT1"
118	><A
119	NAME="AEN7946"
120	></A
121	><H2
122	>Description</H2
123	><P
124	><TT
125	CLASS="FUNCTION"
126	>SDL_CreateSemaphore()</TT
127	> creates a new semaphore and
128	initializes it with the value <TT
129	CLASS="PARAMETER"
130	><I
131	>initial_value</I
132	></TT
133	>.
134	Each locking operation on the semaphore by
135	<A
136	HREF="sdlsemwait.html"
137	>SDL_SemWait</A
138	>,
139	<A
140	HREF="sdlsemtrywait.html"
141	>SDL_SemTryWait</A
142	> or
143	<A
144	HREF="sdlsemwaittimeout.html"
145	>SDL_SemWaitTimeout</A
146	>
147	will atomically decrement the semaphore value. The locking operation will be blocked
148	if the semaphore value is not positive (greater than zero). Each unlock operation by
149	<A
150	HREF="sdlsempost.html"
151	>SDL_SemPost</A
152	>
153	will atomically increment the semaphore value.</P
154	></DIV
155	><DIV
156	CLASS="REFSECT1"
157	><A
158	NAME="AEN7955"
159	></A
160	><H2
161	>Return Value</H2
162	><P
163	>Returns a pointer to an initialized semaphore or
164	<SPAN
165	CLASS="RETURNVALUE"
166	>NULL</SPAN
167	> if there was an error.</P
168	></DIV
169	><DIV
170	CLASS="REFSECT1"
171	><A
172	NAME="AEN7959"
173	></A
174	><H2
175	>Examples</H2
176	><P
177	><PRE
178	CLASS="PROGRAMLISTING"
179	>SDL_sem *my_sem;
180
181	my_sem = SDL_CreateSemaphore(INITIAL_SEM_VALUE);
182
183	if (my_sem == NULL) {
184	return CREATE_SEM_FAILED;
185	}</PRE
186	></P
187	></DIV
188	><DIV
189	CLASS="REFSECT1"
190	><A
191	NAME="AEN7963"
192	></A
193	><H2
194	>See Also</H2
195	><P
196	><A
197	HREF="sdldestroysemaphore.html"
198	><TT
199	CLASS="FUNCTION"
200	>SDL_DestroySemaphore</TT
201	></A
202	>,
203	<A
204	HREF="sdlsemwait.html"
205	><TT
206	CLASS="FUNCTION"
207	>SDL_SemWait</TT
208	></A
209	>,
210	<A
211	HREF="sdlsemtrywait.html"
212	><TT
213	CLASS="FUNCTION"
214	>SDL_SemTryWait</TT
215	></A
216	>,
217	<A
218	HREF="sdlsemwaittimeout.html"
219	><TT
220	CLASS="FUNCTION"
221	>SDL_SemWaitTimeout</TT
222	></A
223	>,
224	<A
225	HREF="sdlsempost.html"
226	><TT
227	CLASS="FUNCTION"
228	>SDL_SemPost</TT
229	></A
230	>,
231	<A
232	HREF="sdlsemvalue.html"
233	><TT
234	CLASS="FUNCTION"
235	>SDL_SemValue</TT
236	></A
237	></P
238	></DIV
239	><DIV
240	CLASS="NAVFOOTER"
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242	ALIGN="LEFT"
243	WIDTH="100%"><TABLE
244	SUMMARY="Footer navigation table"
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248	CELLSPACING="0"
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251	WIDTH="33%"
252	ALIGN="left"
253	VALIGN="top"
254	><A
255	HREF="sdlmutexv.html"
256	ACCESSKEY="P"
257	>Prev</A
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266	>Home</A
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273	HREF="sdldestroysemaphore.html"
274	ACCESSKEY="N"
275	>Next</A
276	></TD
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281	ALIGN="left"
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283	>SDL_mutexV</TD
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290	ACCESSKEY="U"
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293	><TD
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297	>SDL_DestroySemaphore</TD
298	></TR
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303	>