Added sleep syscall

src/common/common.c

@@ -52,6 +52,10 @@ void kill(uint32_t pid) {
   asm volatile("mov $17, %%eax; mov %0, %%esi; int $0x7f" : : "m" (pid) : "esi");
 }
 
+void sleep(uint32_t time) {
+  asm volatile("mov $18, %%eax; mov %0, %%esi; int $0x7f" : : "m" (time) : "esi");
+}
+
 void bindToKeyboard() {
   asm volatile ("mov $12, %%eax; int $0x7f" : : :);
 }

src/common/common.h

@@ -22,6 +22,7 @@ void bindToKeyboard();
 int fopen(char* filename);
 void fclose(uint32_t fh);
 void kill(uint32_t pid);
+void sleep(uint32_t time);
 
 int int_to_decimal(unsigned int number, char* string_buffer);
 int int_to_hex(unsigned int number, char* string_buffer);

src/kernel/datatypes/linkedlist.h

@@ -105,10 +105,10 @@ namespace xnoe {
             current->next->prev = current->prev;
 
           if (current == start)
-            start = 0;
+            start = current->next;
 
           if (current = end)
-            end = 0;
+            end = current->prev;
 
           return;
         }

src/kernel/idt.cpp

@@ -97,6 +97,7 @@ void context_switch(frame_struct* frame) {
   // - Determines if it has 2 or more elements
   //   - If it has two, swap the first and last, update prev and next of each to be null or the other item
   //   - If it has more than two, add the start to the end then set start to the second element
+  do {
     if (Global::currentProc) {
       if (processes->start->next != 0) {
         if (processes->end->prev == processes->start) {
@@ -119,8 +120,9 @@ void context_switch(frame_struct* frame) {
         }
       }
     }
-
     Global::currentProc = processes->start->elem;
+  } while (Global::currentProc->state == Suspended);
+
   
   // Select the next processes page directory
   frame->new_cr3 = Global::currentProc->PD->phys_addr;
@@ -134,7 +136,8 @@ void context_switch(frame_struct* frame) {
 }
 
 namespace Timer {
-  using TimedEvent = xnoe::tuple<uint32_t, uint32_t, void(*)(frame_struct*, void*), void*>;
+  // counter, default count, function, argument, oneshot
+  using TimedEvent = xnoe::tuple<uint32_t, uint32_t, void(*)(frame_struct*, void*), void*, bool>;
   xnoe::linkedlist<TimedEvent> timed_events;
   void tick(frame_struct* frame) {
     xnoe::linkedlistelem<TimedEvent>* current = timed_events.start;
@@ -144,17 +147,28 @@ namespace Timer {
       if (--count == 0) {
         xnoe::get<2>(t)(frame, xnoe::get<3>(t));
         count = xnoe::get<1>(t);
+
+        if (xnoe::get<4>(t)) {
+          xnoe::linkedlistelem<TimedEvent>* prev = current;
+          current = current->next;
+          timed_events.remove(prev);
+          delete prev;
         }
-      current->elem = TimedEvent(count, xnoe::get<1>(t), xnoe::get<2>(t), xnoe::get<3>(t));
+      }
+      current->elem = TimedEvent(count, xnoe::get<1>(t), xnoe::get<2>(t), xnoe::get<3>(t), xnoe::get<4>(t));
       current = current->next;
     }
   }
 
-  void register_event(uint32_t milliseconds, void(*function)(frame_struct*, void*), void* auxiliary) {
+  void register_event(uint32_t milliseconds, void(*function)(frame_struct*, void*), void* auxiliary, bool oneshot=false) {
-    timed_events.append(TimedEvent(milliseconds, milliseconds, function, auxiliary));
+    timed_events.append(TimedEvent(milliseconds, milliseconds, function, auxiliary, oneshot));
   }
 }
 
+void awaken(frame_struct* frame, Process* p) {
+  p->state = Running;
+}
+
 void syscall(frame_struct* frame) {
   // Syscall ABI:
   // 0: X
@@ -179,6 +193,8 @@ void syscall(frame_struct* frame) {
 
   // 17: kill :: int PID esi -> void // Destroys a process.
 
+  // 18: sleep :: int time ms esi -> void // Sleeps the current process for esi milliseconds.
+
   // File handlers:
   // 0: Stdout
   // 1: Stdin
@@ -324,6 +340,13 @@ void syscall(frame_struct* frame) {
       break;
     }
 
+    case 18: {
+      Global::currentProc->state = Suspended;
+      Timer::register_event(esi, &awaken, (void*)Global::currentProc, true);
+      context_switch(frame);
+      break;
+    }
+
     default:
       break;
   }

src/kernel/process.cpp

@@ -22,6 +22,7 @@ Process::Process(uint32_t PID, void* stack, PageDirectory* page_directory, PageM
   this->page_remaining = 0;
   this->last_page_pointer = virt_alloc_base;
   this->stack = stack;
+  this->state = Running;
 }
 
 Process::Process(uint32_t PID)
@@ -31,6 +32,7 @@ Process::Process(uint32_t PID)
   this->last_page_pointer = 0;
   this->stack = this->allocate(0x8000);
   this->kernelStackPtr = (new uint8_t[0x1000]) + 0x1000;
+  this->state = Running;
 }
 
 Process::Process(uint32_t PID, PageDirectory* inherit, uint32_t inheritBase, uint32_t fh)
@@ -43,6 +45,7 @@ Process::Process(uint32_t PID, PageDirectory* inherit, uint32_t inheritBase, uin
   this->PID = PID;
   this->page_remaining = 0;
   this->last_page_pointer = 0;
+  this->state = Running;
 
   for (int index = inheritBase >> 22; index < 1024; index++)
     this->PD->page_directory[index] = inherit->page_directory[index];

src/kernel/process.h

@@ -20,6 +20,11 @@ struct AllocTracker {
   AllocTracker(void* base, uint32_t size, uint32_t count);
 };
 
+enum ProcessState {
+  Running,
+  Suspended
+};
+
 class Process : public Allocator {
 private:
   uint32_t last_page_pointer;
@@ -44,6 +49,8 @@ public:
 
   bool firstRun;
 
+  ProcessState state;
+
   Process(uint32_t PID, void* stack, PageDirectory* page_directory, PageMap* phys, PageMap* virt, uint32_t virt_alloc_base);
   Process(uint32_t PID);
   Process(uint32_t PID, PageDirectory* inherit, uint32_t inheritBase, uint32_t fh);

src/kernel/terminal.h

@@ -14,7 +14,7 @@
 struct frame_struct;
 
 namespace Timer {
-  void register_event(uint32_t milliseconds, void(*function)(frame_struct*, void*), void* auxiliary);
+  void register_event(uint32_t milliseconds, void(*function)(frame_struct*, void*), void* auxiliary, bool oneshot=false);
 }
 
 class Terminal: public ReadWriter {

src/programs/timer/timer.c

@@ -0,0 +1,8 @@
+#include "common/common.h"
+
+int main() {
+  while (1) {
+    print("Hello, World!\n");
+    sleep(200);
+  }
+}

src/programs/world/world.c

@@ -187,7 +187,7 @@ int main() {
   uint32_t p1out = bindStdout(p1);
   uint32_t p1in = bindStdin(p1);
   fclose(program);
-  program = fopen("/hello.bin");
+  program = fopen("/timer.bin");
   uint32_t p2 = fork(program);
   uint32_t p2out = bindStdout(p2);
   uint32_t p2in = bindStdin(p2);