Function comments (v1)

src/time/timer.c

@@ -7,6 +7,7 @@
 #include <stdint.h>
 #include "io/serial/serial.h"
 #include <kernel.h>
+#include "config.h"
 
 /*
 For now, the timer module will be using the PIC.
@@ -20,6 +21,13 @@ volatile uint64_t ticks = 0;
 
 extern struct init_status init;
 
+/*
+ * pic_remap - Remap the Programmable Interrupt Controller
+ *
+ * By default, interrupts are mapped at the wrong place.
+ * This function remaps interrupt numbers so interrupts
+ * don't conflict with each other. 
+ */
 void pic_remap()
 {
     uint8_t master_mask = inb(0x21);
@@ -47,6 +55,12 @@ void pic_remap()
     outb(0xA1, slave_mask);
 }
 
+/*
+ * pic_enable - Enable the Programmable Interrupt Controller
+ *
+ * This function enables IRQ0 and IRQ1, which correspond to
+ * the timer and keyboard interrupts, respectively.
+ */
 void pic_enable()
 {
     // Enabling IRQ0 (unmasking it) but not the others
@@ -57,12 +71,15 @@ void pic_enable()
 }
 
 /*
-Base frequency = 1.193182 MHz
-1 tick per ms (divide by 1000) = roughly 1193 Hz
-*/
+ * pit_init - Initialization of the Programmable Interval Timer
+ *
+ * The PIT is the simplest timer we can get working on x86.
+ * It has a base frequency of 1.193182 MHz.
+ * A custom frequency can be set using TIMER_FREQUENCY macro.
+ */
 void pit_init()
 {
-    uint32_t frequency = 1000; // 1 kHz
+    uint32_t frequency = TIMER_FREQUENCY;
     uint32_t divisor = 1193182 / frequency;
 
     // Set PIT to mode 3, channel 0
@@ -73,8 +90,12 @@ void pit_init()
     outb(0x40, (divisor >> 8) & 0xFF);
 }
 
-// Wait n ticks
-// Given that there's a tick every 1ms, wait n milliseconds
+/*
+ * timer_wait - Wait for X ticks
+ *
+ * By default, the timer frequency is 1000Hz, meaning
+ * ticks are equal to milliseconds.
+ */
 void timer_wait(uint64_t wait_ticks)
 {
     uint64_t then = ticks + wait_ticks;
@@ -83,6 +104,11 @@ void timer_wait(uint64_t wait_ticks)
     };
 }
 
+/*
+ * timer_init - Initialization of the timer
+ *
+ * This function wakes the PIT.
+ */
 void timer_init()
 {
     // Remapping the PIC, because at startup it conflicts with