From 57a6d51e681ed75f105a42deca499a58616abd10 Mon Sep 17 00:00:00 2001
From: rami <rami.kaldany@pm.me>
Date: Tue, 2 Jul 2024 00:46:29 -0400
Subject: [PATCH] pit and kernel ticks

---
 Makefile                |  1 -
 include/kernel/kernel.h |  1 +
 include/kernel/pit.h    |  4 ++++
 kernel/kernel.c         |  9 ++++++++-
 kernel/pic.c            |  4 ++--
 kernel/pit.c            | 13 +++++++++----
 6 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/Makefile b/Makefile
index 6cd44e8..694b88f 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,6 @@ ISO := Hazel.iso
 CFLAGS    := -ffreestanding -Wall -Wextra -Werror -I $(INCLUDEDIR) -I lib
 LDFLAGS   := -ffreestanding -nostdlib -lgcc -T kernel/kernel.ld
 QEMUFLAGS := -cdrom $(BUILDDIR)/$(ISO) \
-			 -d int \
 			 -serial stdio
 
 $(BUILDDIR)/$(KIMG): $(KOBJ) $(LOBJ)
diff --git a/include/kernel/kernel.h b/include/kernel/kernel.h
index 263199f..3e69dbc 100644
--- a/include/kernel/kernel.h
+++ b/include/kernel/kernel.h
@@ -11,6 +11,7 @@ typedef struct {
    multiboot_memory_map_t *mem_map;
    uint32_t mem_map_len;
    log_method_t log_method;
+   uint64_t ticks;
 } kernel_ctx_t;
 
 #endif
diff --git a/include/kernel/pit.h b/include/kernel/pit.h
index 8b1ebda..a82073f 100644
--- a/include/kernel/pit.h
+++ b/include/kernel/pit.h
@@ -11,6 +11,10 @@
 #define PIT_LOHIGH (3<<4)
 #define PIT_CHAN0  0
 
+#define PIT_FREQUENCY 1193182
+#define DESIRED_FREQUENCY 100
+#define DIVISOR (PIT_FREQUENCY/DESIRED_FREQUENCY)
+
 void pit_init(void);
 void pit_handler(void);
 
diff --git a/kernel/kernel.c b/kernel/kernel.c
index d14a668..b6b6aef 100644
--- a/kernel/kernel.c
+++ b/kernel/kernel.c
@@ -19,6 +19,12 @@ void exception_handler(int_stack_frame_t r) {
             r.eip, r.cs, r.eflags);
 }
 
+void sleep(int delay) {
+    uint64_t end = ctx.ticks + delay;
+    while (ctx.ticks < end)
+	cpu_relax;
+}
+
 void kernel(multiboot_info_t *info) {
     if (!CHECK_FLAG(info->flags, 6)) goto halt;  // Memory map
     if (!CHECK_FLAG(info->flags, 12)) goto halt; // VBE data 
@@ -41,8 +47,9 @@ void kernel(multiboot_info_t *info) {
     pic_remap(PIC_1_START, PIC_2_START);
     asm volatile ("sti" ::);
 
+    ctx.ticks = 0;
     pit_init();
+
 halt:
-    asm volatile ("cli" ::);
     for (;;) {}
 }
diff --git a/kernel/pic.c b/kernel/pic.c
index 851f5f2..c49ef35 100644
--- a/kernel/pic.c
+++ b/kernel/pic.c
@@ -26,6 +26,6 @@ void pic_remap(int pic1_start, int pic2_start) {
     outb(PIC_2_DATA, 0x01);
 
     // Unmask
-    //outb(PIC_1_DATA, 0b11111101);
-    //outb(PIC_2_DATA, 0b11111101);
+    outb(PIC_1_DATA, 0b11111110);
+    outb(PIC_2_DATA, 0b11111110);
 }
diff --git a/kernel/pit.c b/kernel/pit.c
index 95ea6c6..930e69b 100644
--- a/kernel/pit.c
+++ b/kernel/pit.c
@@ -1,14 +1,19 @@
+#include <kernel/kernel.h>
 #include <kernel/pit.h>
 #include <kernel/io.h>
 #include <kernel/pic.h>
 
-void pit_init(void) {
-    outb(PIT_MODE_CMD, PIT_CHAN0 | PIT_LOHIGH | PIT_MODE0);
+extern kernel_ctx_t ctx;
 
-    outb(PIT_CHAN0, 1);
-    outb(PIT_CHAN0, 0);
+void pit_init(void) {
+    outb(PIT_MODE_CMD, PIT_CHAN0 | PIT_LOBYTE | PIT_MODE0);
+
+    outb(PIT_CHAN0_DATA, (uint8_t)(DIVISOR & 0xff));
 }
 
 void pit_handler(void) {
+    ctx.ticks++;
+
+    outb(PIT_CHAN0_DATA, (uint8_t)(DIVISOR & 0xff));
     pic_send_eoi(0);
 }