From adfb2c00592e08815a546548f3e87809a645696c Mon Sep 17 00:00:00 2001
From: Aqua-sama <aqua@iserlohn-fortress.net>
Date: Sat, 6 Mar 2021 17:51:05 +0200
Subject: scheduler: fix task switching

---
 src/idt/stubs.S  |  7 ++++---
 src/scheduler.cc | 25 +++++++++++++++----------
 src/scheduler.h  |  2 +-
 3 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/src/idt/stubs.S b/src/idt/stubs.S
index 4f1440d..d4fb56f 100644
--- a/src/idt/stubs.S
+++ b/src/idt/stubs.S
@@ -82,13 +82,14 @@ exception_common:
     iret
 
 interrupt_common:
-    pusha
+    pushal
 
     push %esp
     call handle_interrupt
-    add $4, %esp
+    #add $4, %esp
+    mov %eax, %esp
 
-    popa
+    popal
     /* remove error code and irq from stack */
     add $8, %esp
 
diff --git a/src/scheduler.cc b/src/scheduler.cc
index 1557e28..4de9fff 100644
--- a/src/scheduler.cc
+++ b/src/scheduler.cc
@@ -9,20 +9,24 @@ void task_b(void) {
   while (true) printk("B");
 }
 
+constexpr uint16_t max_tasks = 256;
+static cpu_state_t* tasks[max_tasks];
+
 static uint8_t stack_a[4096] = {0};
 static uint8_t stack_b[4096] = {0};
-constexpr uint16_t max_tasks = 2;
-static cpu_state_t* tasks[max_tasks];
 
 Scheduler::Scheduler(uint16_t cs) : InterruptHandler(0x00) {
-  add_task(stack_a, cs, &task_a);
-  add_task(stack_b, cs, task_b);
+  printk("add_task: ", add_task(stack_b, cs, task_b), '\n');
+  printk("add_task: ", add_task(stack_a, cs, task_a), '\n');
+
+  printk("task0 eip: ", uhex{tasks[0]->eip}, '\n');
+  printk("task1 eip: ", uhex{tasks[1]->eip}, '\n');
 }
 
-bool Scheduler::add_task(uint8_t* stack, uint16_t cs, void (*entry)()) {
-  if (last_task_id == uint16_t_max) return false;
+uint16_t Scheduler::add_task(uint8_t* stack, uint16_t cs, void (*entry)()) {
+  if (last_task_id == (max_tasks - 1)) return 0;
 
-  uint16_t id = last_task_id++;
+  uint16_t id = ++last_task_id;
   ++num_tasks;
 
   cpu_state_t* cpu_state = reinterpret_cast<cpu_state_t*>(stack + 4096 - sizeof(cpu_state_t));
@@ -33,14 +37,15 @@ bool Scheduler::add_task(uint8_t* stack, uint16_t cs, void (*entry)()) {
   tasks[id] = cpu_state;
   printk("adding task: cs ", uhex{cpu_state->cs}, " stack ", uhex{reinterpret_cast<uint32_t>(tasks[id])}, " entry ",
          uhex{cpu_state->eip}, '\n');
-  return true;
+  return id;
 }
 
 cpu_state_t* Scheduler::trigger(cpu_state_t* cpu) {
   tasks[current_task] = cpu;
 
-  if (++current_task >= num_tasks) current_task %= num_tasks;
+  current_task++;
+  if (current_task > num_tasks) current_task = 0;
 
-  // printk("swapped to task ", current_task, '\n');
+  printk("\n\nswapped to task ", current_task, '\n');
   return tasks[current_task];
 }
diff --git a/src/scheduler.h b/src/scheduler.h
index 9e5e9f2..a3148bb 100644
--- a/src/scheduler.h
+++ b/src/scheduler.h
@@ -7,7 +7,7 @@ class Scheduler : public InterruptHandler {
 public:
   Scheduler(uint16_t cs);
 
-  bool add_task(uint8_t* stack, uint16_t cs, void (*entry)());
+  [[nodiscard]] uint16_t add_task(uint8_t* stack, uint16_t cs, void (*entry)());
   [[nodiscard]] cpu_state_t* trigger(cpu_state_t*) override;
 
 private:
-- 
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