forked from BSB-WS23/mpstubs
98 lines
2.2 KiB
C++
98 lines
2.2 KiB
C++
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#include "types.h"
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#include "machine/lapic.h"
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#include "machine/lapic_registers.h"
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#include "machine/core.h"
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namespace LAPIC {
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namespace Timer {
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/*! \brief Timer Delivery Status */
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enum DeliveryStatus {
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IDLE = 0,
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SEND_PENDING = 1
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};
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/*! \brief Timer Mode */
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enum TimerMode {
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ONE_SHOT = 0,
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PERIODIC = 1,
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DEADLINE = 2
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// reserved
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};
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/*! \brief Timer Mask */
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enum Mask {
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NOT_MASKED = 0,
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MASKED = 1
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};
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static const Register INVALID_DIV = 0xff;
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/*! \brief LAPIC-Timer Control Register
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*
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* \see [ISDMv3 10.5.1 Local Vector Table](intel_manual_vol3.pdf#page=375)
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*/
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union ControlRegister {
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struct {
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uint32_t vector : 8; ///< Vector
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uint32_t : 4;
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DeliveryStatus delivery_status : 1; ///< Delivery Status
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uint32_t : 3;
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Mask masked : 1; ///< Interrupt Mask (if set, interrupt will not trigger)
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TimerMode timer_mode : 2; ///< Timer Mode
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uint32_t : 13;
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};
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Register value;
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} __attribute__((packed));
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/*! \brief LAPIC timer divider table
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*
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* \see [ISDMv3 10.5.4 APIC Timer](intel_manual_vol3.pdf#page=378)
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*/
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static const Register div_masks[] = {
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0xb, ///< divides by 1
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0x0, ///< divides by 2
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0x1, ///< divides by 4
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0x2, ///< divides by 8
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0x3, ///< divides by 16
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0x8, ///< divides by 32
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0x9, ///< divides by 64
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0xa ///< divides by 128
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};
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/*! \brief Calculate the bit mask for the LAPIC-timer divider.
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* \param div Divider, must be power of two: 1, 2, 4, 8, 16, 32, 64, 128
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* \return Bit mask for LAPIC::Timer::set() or `0xff` if `div` is invalid.
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*/
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Register getClockDiv(uint8_t div) {
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// div is zero or not a power of two?
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if (div == 0 || (div & (div - 1)) != 0) {
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return INVALID_DIV;
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}
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int trail = __builtin_ctz(div); // count trailing 0-bits
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if (trail > 7) {
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return INVALID_DIV;
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}
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return div_masks[trail];
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}
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uint32_t ticks(void) {
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uint32_t ticks = 0; // ticks per millisecond
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// Calculation (Assignment 5)
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return ticks;
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}
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void set(uint32_t counter, uint8_t divide, uint8_t vector, bool periodic, bool masked) {
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(void) counter;
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(void) divide;
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(void) vector;
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(void) periodic;
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(void) masked;
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}
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} // namespace Timer
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} // namespace LAPIC
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