From 5663c3daac784a3078be168b6ce0dedb254a6e26 Mon Sep 17 00:00:00 2001
From: tone121 <tone121@cox.net>
Date: Mon, 19 Feb 2018 20:17:49 -0700
Subject: [PATCH] more scheduler crap preemptive scheduling is hard, so i went
 back to cooperative scheduling.

---
 include/sched/sched.h |  5 +---
 src/boot/init.c       |  8 +++---
 src/sched/sched.c     | 57 ++++++-------------------------------------
 src/sched/switch.asm  | 10 ++------
 4 files changed, 14 insertions(+), 66 deletions(-)

diff --git a/include/sched/sched.h b/include/sched/sched.h
index 469f7b9..d53060d 100644
--- a/include/sched/sched.h
+++ b/include/sched/sched.h
@@ -1,9 +1,6 @@
 #ifndef SCHED_H
 #define SCHED_H
 
-#include <cpu/idt.h>
-#include <cpu/pic.h>
-#include <cpu/pit.h>
 #include <tty/panic.h>
 #include <sched/process.h>
 
@@ -11,6 +8,6 @@ void sched_init(process_t *proc);
 void sched_add(process_t *proc);
 void sched_remove(process_t *proc);
 unsigned long sched_pid_alloc(void);
-unsigned long sched_step(void);
+void sched_step(void);
 
 #endif
diff --git a/src/boot/init.c b/src/boot/init.c
index f49133f..31c5449 100644
--- a/src/boot/init.c
+++ b/src/boot/init.c
@@ -35,9 +35,8 @@ void init_arch(struct multiboot_info *mb)
 
 void idle(void)
 {
-	for (;;) {
-		asm ("nop");
-	}
+	tty_printf("a");
+	asm ("nop");
 }
 
 void init(struct multiboot_info *mb)
@@ -48,7 +47,8 @@ void init(struct multiboot_info *mb)
 
 	sched_init(process_init(idle, "idle"));
 
-	idle();
+	for (;;)
+		sched_step();
 
 	return;
 }
diff --git a/src/sched/sched.c b/src/sched/sched.c
index 88277d7..38d0744 100644
--- a/src/sched/sched.c
+++ b/src/sched/sched.c
@@ -5,45 +5,6 @@ extern void sched_jump(unsigned long eip);
 static process_t *curr = NULL;
 static unsigned long pid = 0;
 
-void sched_int(void)
-{
-	asm ("cli");
-
-	asm ("out %%al, %%dx" : : "d"(0x20), "a"(0x20));
-
-	// save registers
-	asm ("mov %%ebx, %0" : "=r"(curr->regs.ebx));
-	asm ("mov %%ecx, %0" : "=r"(curr->regs.ecx));
-	asm ("mov %%edx, %0" : "=r"(curr->regs.edx));
-
-	asm ("mov %%esi, %0" : "=r"(curr->regs.esi));
-	asm ("mov %%edi, %0" : "=r"(curr->regs.edi));
-
-	asm ("mov %%esp, %0" : "=r"(curr->regs.esp));
-	asm ("mov %%ebp, %0" : "=r"(curr->regs.ebp));
-	
-	asm ("mov 12(%%esp), %0" : "=r"(curr->regs.eip));
-
-	if (sched_step() == 1) {
-
-		// restore registers
-
-		asm ("mov %0, %%ebx" : "=r"(curr->regs.ebx));
-		asm ("mov %0, %%ecx" : "=r"(curr->regs.ecx));
-		asm ("mov %0, %%edx" : "=r"(curr->regs.edx));
-
-		asm ("mov %0, %%esi" : "=r"(curr->regs.esi));
-		asm ("mov %0, %%edi" : "=r"(curr->regs.edi));
-
-	//	asm ("mov %0, %%esp" : "=r"(curr->regs.esp));
-	//	asm ("mov %0, %%ebp" : "=r"(curr->regs.ebp));
-
-		sched_jump(curr->regs.eip);
-	}
-
-	asm ("sti; leave; iret");
-}
-
 void sched_init(process_t *proc)
 {
 	if (proc) {
@@ -51,10 +12,6 @@ void sched_init(process_t *proc)
 
 		curr->prev = curr;
 		curr->next = curr;
-	
-		idt_set_entry(32, (unsigned long)sched_int);
-		pit_set_phase(PIT_HZ / 1000);
-		pic_enable_irq(0);
 	}
 }
 
@@ -81,14 +38,16 @@ unsigned long sched_pid_alloc(void)
 	return pid++;
 }
 
-unsigned long sched_step(void)
+void sched_step(void)
 {
-	unsigned long schedule = 0;
-
 	if (curr && curr->next) {
 		switch (curr->state) {
+		case PROCESS_RUNNING:
+			PANIC("trying to schedule a running process!");
 		case PROCESS_RUNABLE:
-			schedule = 1;
+			curr->state = PROCESS_RUNNING;
+			sched_jump(curr->regs.eip);
+			curr->state = PROCESS_RUNABLE;
 			break;
 		case PROCESS_SLEEPING:
 			// do nothing and let it sleep
@@ -96,7 +55,7 @@ unsigned long sched_step(void)
 		case PROCESS_ZOMBIE:
 			curr = curr->next;
 			sched_remove(curr->prev);
-			return 0;
+			return;
 		default:
 			PANIC("cannot handle unknown process state!");
 		}
@@ -104,6 +63,4 @@ unsigned long sched_step(void)
 	} else {
 		PANIC("no more processes to schedule!");
 	}
-
-	return schedule;
 }
diff --git a/src/sched/switch.asm b/src/sched/switch.asm
index 9c0ce99..08f8be1 100644
--- a/src/sched/switch.asm
+++ b/src/sched/switch.asm
@@ -2,12 +2,6 @@
 ; void sched_jump(unsigned long eip);
 global sched_jump
 sched_jump:
-	pop eax
-	
-	pushfd
-	or dword [esp], 0x200
-	push 0x8
-	push eax
-
-	iret
+	mov eax, [esp + 4]
+	jmp eax
  
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