voron

commit 27311c2f3d0fe52542c0ad0e356a0d5140b5cc93
parent 87c996caabb6a92cbc8586758c0c5028b64de8d7
Author: oblique <psyberbits@gmail.com>
Date:   Thu,  1 Nov 2012 17:11:18 +0200

add semaphore and mutex

Diffstat:
A
include/semaphore.h
 | 
98
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
kernel/kmain.c
 | 
18
++++++++++++++++--

2 files changed, 114 insertions(+), 2 deletions(-)
diff --git a/include/semaphore.h b/include/semaphore.h
@@ -0,0 +1,98 @@
+#ifndef __SEMAPHORE_H
+#define __SEMAPHORE_H
+
+#include <io.h>
+#include <sched.h>
+
+typedef struct {
+	u32 counter;
+} semaphore_t;
+
+typedef struct {
+	semaphore_t sem;
+} mutex_t;
+
+#define SEMAPHORE_INIT(v)	{ (v) }
+
+static inline void
+semaphore_init(semaphore_t *sem, u32 value)
+{
+	sem->counter = value;
+}
+
+static inline int
+semaphore_trywait(semaphore_t *sem)
+{
+	u32 tmp;
+
+	asm volatile (
+		"ldrex v1, [%1]		\n\t"
+		"teq v1, #0		\n\t"
+		"moveq %0, #1		\n\t"
+		"subne v1, v1, #1	\n\t"
+		"strexne %0, v1, [%1]	\n\t"
+		: "=&r" (tmp)
+		: "r" (&sem->counter)
+		: "v1", "memory", "cc"
+	);
+
+	if (tmp == 0) {
+		dmb();
+		return 1;
+	} else
+		return 0;
+}
+
+static inline void
+semaphore_wait(semaphore_t *sem)
+{
+	while (!semaphore_trywait(sem))
+		suspend_task((u32)sem);
+}
+
+static inline void
+semaphore_done(semaphore_t *sem)
+{
+	dmb();
+	asm volatile (
+		"1:			\n\t"
+		"ldrex v1, [%0]		\n\t"
+		"add v1, v1, #1		\n\t"
+		"strex v2, v1, [%0]	\n\t"
+		"teq v2, #0		\n\t"
+		"bne 1b			\n\t"
+		:
+		: "r" (&sem->counter)
+		: "v1", "v2", "memory", "cc"
+	);
+	dmb();
+	resume_tasks((u32)sem);
+}
+
+#define MUTEX_INIT	{ SEMAPHORE_INIT(1) }
+
+static inline void
+mutex_init(mutex_t *mut)
+{
+	semaphore_init(&mut->sem, 1);
+}
+
+static inline int
+mutex_trylock(mutex_t *mut)
+{
+	return semaphore_trywait(&mut->sem);
+}
+
+static inline void
+mutex_lock(mutex_t *mut)
+{
+	semaphore_wait(&mut->sem);
+}
+
+static inline void
+mutex_unlock(mutex_t *mut)
+{
+	semaphore_done(&mut->sem);
+}
+
+#endif	/* __SEMAPHORE_H */
diff --git a/kernel/kmain.c b/kernel/kmain.c
@@ -1,13 +1,26 @@
 #include <kernel.h>
 #include <sched.h>
+#include <semaphore.h>
+
+semaphore_t sem = SEMAPHORE_INIT(2);
 
 static void
 thread_func(void *arg)
 {
-	u32 n = (u32)arg;
+	u32 i = 0, n = (u32)arg;
 	while (1) {
-		kprintf("thread %d\n", n);
+		if (i == 5 * n) {
+			kprintf("thread %d waiting semaphore\n", n);
+			semaphore_wait(&sem);
+			kprintf("thread %d locked semaphore\n", n);
+		}
+		kprintf("thread %d  i: %d\n", n, i);
 		msleep(500);
+		i++;
+		if (i == 20 * n) {
+			semaphore_done(&sem);
+			kprintf("thread %d released semaphore\n", n);
+		}
 	}
 }
 
@@ -17,4 +30,5 @@ kmain(void)
 	kprintf("voron initial stage\n\n");
 	kthread_create(thread_func, (void*)1);
 	kthread_create(thread_func, (void*)2);
+	kthread_create(thread_func, (void*)3);
 }