From: Matthias Kruk <m@m10k.eu>
Date: Fri, 27 Sep 2019 07:10:31 +0000 (+0900)
Subject: Add a _very_ naive scheduler
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=4172508cb546b3ded3b6447e7f1338e053d6bf93;p=corax

Add a _very_ naive scheduler
---

diff --git a/kernel/arch/interrupt.c b/kernel/arch/interrupt.c
index b8b9677..8649a4a 100644
--- a/kernel/arch/interrupt.c
+++ b/kernel/arch/interrupt.c
@@ -22,6 +22,8 @@
 #include "cpu.h"
 #include "defs.h"
 
+void sched_tick(void);
+
 static const char *_exc_name[] = {
     "#DE", "#DB", "NMI", "#BP", "#OF", "#BR", "#UD", "#NM", "#DF", "#MF",
     "#TS", "#NP", "#SS", "#GP", "#PF", "RESV", "#MF", "#AC", "#MC", "#XM",
@@ -61,7 +63,8 @@ int _int_handle(stack_frame_t ctx)
     */
 /*    PANIC("Unhandled interrupt"); */
 
-    if(ctx.intn == INT_KEYBOARD) {
+	switch(ctx.intn) {
+	case INT_KEYBOARD: {
 #if FEATURE(DEBUG)
         extern struct cpu _cpu[CONFIG_SMP_CPUS];
 #endif /* FEATURE(DEBUG) */
@@ -80,8 +83,16 @@ int _int_handle(stack_frame_t ctx)
 		 * could not cause a triple fault */
 		asm volatile("ljmp $0x30, $0xfee00020"); /* LEEROY JENKINS!!! */
 #endif /* FEATURE(DEBUG) */
-    } else if(ctx.intn != INT_TIMER) {
+		break;
+	}
+
+	case INT_TIMER:
+		sched_tick();
+		break;
+
+	default:
 		dbg_printf("Interrupt %u occurred\n", ctx.intn);
+		break;
 	}
 
     #if CONFIG_APIC == 1
diff --git a/kernel/core/Makefile b/kernel/core/Makefile
index bb68e27..47a3eea 100644
--- a/kernel/core/Makefile
+++ b/kernel/core/Makefile
@@ -1,4 +1,4 @@
-OBJECTS = main.o process.o
+OBJECTS = main.o process.o sched.o
 OUTPUT = core.o
 INCLUDES = -I../include -I../../include -I../..
 CFLAGS += $(INCLUDES)
diff --git a/kernel/core/sched.c b/kernel/core/sched.c
new file mode 100644
index 0000000..497d504
--- /dev/null
+++ b/kernel/core/sched.c
@@ -0,0 +1,85 @@
+#include <config.h>
+#include <corax/types.h>
+#include <corax/heap.h>
+#include <debug.h>
+#include <arch.h>
+
+struct task_queue {
+	struct task_queue *next;
+	task_t *data;
+};
+
+/* FIXME: This should be per-processor */
+static struct task_queue *_readyq;
+
+static void _nq(struct task_queue **q, task_t *t)
+{
+	struct task_queue *item;
+
+	item = kmalloc(sizeof(*item));
+
+	if(item) {
+		item->data = t;
+
+		/* get a pointer to the end of the queue */
+		while(*q) {
+			q = &((*q)->next);
+		}
+
+		item->next = *q;
+		*q = item;
+	}
+
+	return;
+}
+
+static task_t* _dq(struct task_queue **q)
+{
+	struct task_queue *cur;
+	task_t *ret_val;
+
+	cur = *q;
+	ret_val = NULL;
+
+	if(cur) {
+		*q = cur->next;
+		ret_val = cur->data;
+
+		kfree(cur);
+	}
+
+	return(ret_val);
+}
+
+void sched_tick(void)
+{
+	task_t *cur_task;
+
+	cur_task = task_get_current();
+
+	if(cur_task) {
+		/* check if running task has not used up it's quantum yet */
+		if(cur_task->t_rslice) {
+			cur_task->t_rslice--;
+			return;
+		}
+
+		/* task's time is up - reschedule */
+		cur_task->t_rslice = cur_task->t_tslice;
+		cur_task->t_state = TASK_STATE_READY;
+
+		/* put the task back on the ready queue */
+	    _nq(&_readyq, cur_task);
+
+		/* get the next task from the ready queue */
+		cur_task = _dq(&_readyq);
+
+		if(cur_task) {
+			task_set_current(cur_task);
+		} else {
+			dbg_printf("This should not have happened\n");
+		}
+	}
+
+	return;
+}