Does a lot of work towards the PIT

Added a math library, with clamp and POW.
added printf support for printing doubles
added a few helper functions in PIT for calcaulting the time in seconds of a clock cycle based on divisor

kernel/include/kernel/x86/keyb.h

@@ -1,4 +1,5 @@
 #include <stdint.h>
+#include <stdbool.h>
 
 #ifndef ARCH_KEYB_H
 #define ARCH_KEYB_H

kernel/include/kernel/x86/pit.h

@@ -1,3 +1,5 @@
+#include <stdint.h>
+
 #ifndef ARCH_PIT_H
 #define ARCH_PIT_H
 
@@ -16,6 +18,27 @@ enum PIT_CHANNEL {
 	CHANNEL_0 = 0x0,
 	CHANNEL_1,
 	CHANNEL_2,
+	/**
+	 * Isn't supported on 8253 chips, but should be supported on AT and later (except for PS/2).
+	 *
+	 * Layout goes:
+	 * bits:
+	 * 76 - Set for READ_BACK
+	 * 5 - Latch count flag (0 = latch count, 1 = don't latch count)
+	 * 4 - Latch status flag (0 = latch status, 1 = don't latch status) - If this is clear, the next read of the corresponding data port will be a status byte
+	 * 3 - Read back timer channel 2 (1 = yes, 0 = no)
+	 * 2 - Read back timer channel 1 (..)
+	 * 1 - Read back timer channel 0 (..)
+	 * 0 - Reserved - set to 0
+	 *
+	 * Read back status byte:
+	 * bits:
+	 * 7 - Output pin state
+	 * 6 - Null count flags
+	 * 54 - Access mode
+	 * 321 - Operating mode
+	 * 0 BCD/Binary mode
+	 */ 
 	READ_BACK // 8254 only
 };
 
@@ -28,6 +51,13 @@ enum PIT_CHANNEL {
  * HI AND LOW means that the values will come sequentially through the IO port, lowest followed by highest
  */
 enum PIT_ACCESS_MODE {
+	/*
+	 * To prevent the count from being updated, we can use this command to latch the PIT.
+	 * This must be xx000000 ( where x is the channel ).
+	 * The value for each channel remains latched, until its fully read (or a new CMD has been issued).
+	 * Some older/cheap motherboards have an issue with this command being sent a lot, leading to innaccuracies
+	 * this command shouldn't be sent a lot anyways.
+	 */
 	LATCH_COUNT_VAL_CMD = 0x0,
 	LO_BYTE_ONLY,
 	HI_BYTE_ONLY,
@@ -213,5 +243,16 @@ enum PIT_DIGIT_MODE {
 	BCD_MODE		// four-digit bcd 
 };
 
+struct pit_state {
+	uint32_t divisor;
+} __attribute__((packed));
+
+void init_pit(uint32_t divisor);
+
+double get_time_from_divisor(uint32_t divisor);
+
+
+uint16_t read_pit_count(uint8_t channel);
+void set_pit_count(uint8_t channel, uint16_t count);
 
 #endif