code: drawterm

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Use posix locks instead of pipes.

--- a/kern/posix.c

+++ b/kern/posix.c

@@ -2,6 +2,7 @@

  * Posix generic OS implementation for drawterm.

  */

+#define _XOPEN_SOURCE 500

 #include <pthread.h>

 #include <time.h>

 #include <sys/time.h>

@@ -17,7 +18,10 @@

 typedef struct Oproc Oproc;

 struct Oproc

 {

-	int p[2];

+	int nsleep;

+	int nwakeup;

+	pthread_mutex_t mutex;

+	pthread_cond_t cond;

 };

 static pthread_key_t prdakey;

@@ -51,10 +55,14 @@

 osnewproc(Proc *p)

 {

 	Oproc *op;

+	pthread_mutexattr_t attr;

 	op = (Oproc*)p->oproc;

-	if(pipe(op->p) < 0)

-		panic("cannot pipe");

+	pthread_mutexattr_init(&attr);

+	pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL);

+	pthread_mutex_init(&op->mutex, &attr);

+	pthread_mutexattr_destroy(&attr);

+	pthread_cond_init(&op->cond, 0);

 }

 void

@@ -130,19 +138,24 @@

 	p = up;

 	op = (Oproc*)p->oproc;

-	while(read(op->p[0], &c, 1) != 1)

-		;

+	pthread_mutex_lock(&op->mutex);

+	op->nsleep++;

+	while(op->nsleep > op->nwakeup)

+		pthread_cond_wait(&op->cond, &op->mutex);

+	pthread_mutex_unlock(&op->mutex);

 }

 void

 procwakeup(Proc *p)

 {

-	char c;

 	Oproc *op;

 	op = (Oproc*)p->oproc;

-	c = 'a';

-	write(op->p[1], &c, 1);

+	pthread_mutex_lock(&op->mutex);

+	op->nwakeup++;

+	if(op->nwakeup == op->nsleep)

+		pthread_cond_signal(&op->cond);

+	pthread_mutex_unlock(&op->mutex);

 }

 int randfd;