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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 |
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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 |
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