From c3f45eb5e24777f7dd5d635958455f33085f034d Mon Sep 17 00:00:00 2001
From: Arjob Mukherjee <arjobmukherjee@gmail.com>
Date: Fri, 18 Oct 2024 00:31:20 +0530
Subject: [PATCH] Yield request event is sent regularly to processes

---
 include/applib/app.h        |  7 +++++++
 include/kernel.h            |  7 +++++++
 src/apps/mpdemo.c           | 17 ++++++++++++++---
 src/kernel/x86/interrupts.c |  1 +
 4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/include/applib/app.h b/include/applib/app.h
index 2e76259..d5a95ce 100644
--- a/include/applib/app.h
+++ b/include/applib/app.h
@@ -27,6 +27,13 @@ typedef enum IProcessFlags {
     IPROCESS_FLAGS_KERNEL_PROCESS = (1 << 0),
     IPROCESS_FLAGS_THREAD         = (1 << 1),
 } IProcessFlags;
+
+// Represents the 'KernelEvents' struct defined in 'kernel.h', but with some changes.
+typedef enum IAppEvents {
+    APP_EVENT_NONE               = 0,
+    APP_EVENT_TICK               = 1,
+    APP_EVENT_PROCCESS_YIELD_REQ = 2
+} IAppEvents;
 // =============================================================================
 
 typedef enum SYSCALLS {
diff --git a/include/kernel.h b/include/kernel.h
index b8682b7..803d5b4 100644
--- a/include/kernel.h
+++ b/include/kernel.h
@@ -28,6 +28,12 @@ typedef struct KernelStateInfo {
 
 extern volatile KernelStateInfo g_kstate;
 
+typedef enum KernelEvents {
+    KERNEL_EVENT_NONE = 0,
+    KERNEL_EVENT_TICK = 1,
+    KERNEL_EVENT_PROCCESS_YIELD_REQ = 2
+} KernelEvents;
+
 #define KERNEL_PHASE_SET(p)                                                                    \
     do {                                                                                       \
         k_assert (p == 0 || (g_kstate.phase + 1) == p, "Current state is unsuitable for " #p); \
@@ -42,3 +48,4 @@ extern volatile KernelStateInfo g_kstate;
 #define KERNEL_TICK_COUNT_TO_MICROSEC(tick) ((tick)*CONFIG_TICK_PERIOD_MICROSEC)
 
 void k_delay (UINT ms);
+void keventmanager_invoke();
diff --git a/src/apps/mpdemo.c b/src/apps/mpdemo.c
index 0a75927..9948672 100644
--- a/src/apps/mpdemo.c
+++ b/src/apps/mpdemo.c
@@ -8,6 +8,14 @@ static void s_progressbar (UINT iterPerStep, char* title, UINT row, UINT color);
 static void thread0();
 static void thread1();
 
+static bool shouldYield()
+{
+    UINT pid = sys_process_get_pid();
+    IProcessEvent e;
+    sys_process_pop_event (pid, &e);
+    return (e.event == APP_EVENT_PROCCESS_YIELD_REQ);
+}
+
 static void s_printString (U32 row, U32 col, U32 bgcolor, U32 fgcolor, char* text)
 {
     syscall (SYSCALL_CONSOLE_SETCOLOR, bgcolor, fgcolor, 0, 0, 0);
@@ -27,10 +35,10 @@ void s_progressbar (UINT iterPerStep, char* title, UINT row, UINT color)
         if (i % iterPerStep == 0) {
             column = (column + 1) % MAX_VGA_COLUMNS;
         }
-        sys_yield();
+        if (shouldYield()) {
+            sys_yield();
+        }
     }
-
-    sys_process_kill();
 }
 
 void proc_main()
@@ -50,6 +58,7 @@ void proc_main()
 
     s_progressbar (iterPerStep, "Process 0:\n", 25, RED);
 
+    k_halt();
     sys_process_kill();
     s_printString (37, 0, BLACK, WHITE,
                    "Cannot kill process 0. Make kernel thread slower for demo.");
@@ -60,6 +69,7 @@ void thread0()
     UINT iterPerStep = 10;
 
     s_progressbar (iterPerStep, "Thread 0:\n", 29, GREEN);
+    sys_process_kill();
 }
 
 void thread1()
@@ -67,4 +77,5 @@ void thread1()
     UINT iterPerStep = 7;
 
     s_progressbar (iterPerStep, "Thread 1:\n", 33, YELLOW);
+    sys_process_kill();
 }
diff --git a/src/kernel/x86/interrupts.c b/src/kernel/x86/interrupts.c
index 5201276..a0bd8b4 100644
--- a/src/kernel/x86/interrupts.c
+++ b/src/kernel/x86/interrupts.c
@@ -53,6 +53,7 @@ void timer_interrupt_handler (InterruptFrame* frame)
               "Interrupt timer period != tick period");
 
     g_kstate.tick_count++;
+    keventmanager_invoke();
 
     pic_send_eoi (PIC_IRQ_TIMER);
 }