Subj : pthread_cond to create sema?
To   : comp.programming.threads
From : Paolo
Date : Tue Jan 18 2005 07:15 pm


Are these P() and V() correct if i want to implement
semaphores p() and v() functions?

messagecounter is a global int variable,
semaforo is a mutex used only here
sema is a cond variable



#define P() {\
pthread_mutex_lock(&semaforo);\
while ( TW_messagecounter <= 0) {\
 pthread_cond_wait(&sema, &semaforo);\
}\
messagecounter--;\
pthread_mutex_unlock(&semaforo);\
}

#define V() {\
pthread_mutex_lock(&semaforo);\
messagecounter++;\
pthread_cond_signal(&sema);\
pthread_mutex_unlock(&semaforo);\
}

Thank you!
Paolo

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