arch.x86.util¶

x86 I/O port access, low-level CPU control, timing, and arithmetic utilities.

Overview¶

This unit collects all code that requires direct x86 assembly: port I/O, interrupt flag manipulation, TSC reads, system halt and reset, SSE memory copy, software sleep, bit rotation, and 64-by-32 division. It also exposes the kernel end pointer and stack address symbols from the linker script. Most other units in the x86 architecture layer depend on this unit for hardware access primitives.

Dependencies¶

arch.x86.bda (interface)
arch.x86.cpu
arch.x86.isr.types
driver.timer.rtc
driver.io.serial

Variables¶

endptr¶

var endptr : uint32; external name '__end';

Linker-defined symbol marking the end of the kernel binary image in virtual memory.

stack¶

var stack : uint32; external name 'KERNEL_STACK';

Linker-defined symbol giving the address of the kernel stack.

Functions and Procedures¶

INTE¶

function INTE : boolean;

Returns true if the interrupt enable flag (IF, EFLAGS bit 9) is currently set.

CLI¶

procedure CLI();

Disables maskable interrupts by executing the x86 CLI instruction.

STI¶

procedure STI();

Enables maskable interrupts by executing the x86 STI instruction.

GPF¶

procedure GPF();

Triggers a software General Protection Fault via INT 13. Used by subsystems to signal unrecoverable internal errors in a way that routes through the normal fault handler.

outb¶

procedure outb(port : uint16; val : uint8);

Writes an 8-bit value to an I/O port, followed by io_wait. Also exported as util_outb.

outw¶

procedure outw(port : uint16; val : uint16);

Writes a 16-bit value to an I/O port, followed by io_wait. Also exported as util_outw.

outl¶

procedure outl(port : uint16; val : uint32);

Writes a 32-bit value to an I/O port, followed by io_wait. Also exported as util_outl.

inb¶

function inb(port : uint16) : uint8;

Reads an 8-bit value from an I/O port, followed by io_wait. Also exported as util_inb.

inw¶

function inw(port : uint16) : uint16;

Reads a 16-bit value from an I/O port, followed by io_wait. Also exported as util_inw.

inl¶

function inl(port : uint16) : uint32;

Reads a 32-bit value from an I/O port, followed by io_wait. Also exported as util_inl.

io_wait¶

procedure io_wait;

Writes zero to port $80 (a diagnostic port), providing a brief I/O delay used between successive port writes to slow-responding hardware.

__SSE_128_memcpy¶

procedure __SSE_128_memcpy(source : uint32; dest : uint32);

Copies 16 bytes from source to dest using a single MOVAPS/XMM1 pair. Both addresses must be 16-byte aligned.

halt_and_catch_fire¶

procedure halt_and_catch_fire();

Disables interrupts (CLI) and halts the CPU (HLT). The processor will not resume. Used as the panic halt callback and exported as util_halt_and_catch_fire.

halt_and_dont_catch_fire¶

procedure halt_and_dont_catch_fire();

Spins in an infinite loop without halting the CPU. Exported as util_halt_and_dont_catch_fire. Useful when HLT would be incorrect (e.g., if an NMI handler must remain active).

psleep¶

procedure psleep(t : uint16);

Busy-waits for approximately t BDA timer ticks. If the timer ISR is not yet installed (detected by the tick counter not advancing within 50 000 iterations), falls back to a CPU busy-loop calibrated for roughly millisecond-scale delays per tick. Used for hardware settle times during early boot.

sleep¶

procedure sleep(seconds : uint32);

Waits for seconds RTC seconds by polling the RTC until the seconds field changes seconds times.

get16bitcounter¶

function get16bitcounter : uint16;

Returns the 16-bit system tick counter from arch.x86.bda.Counters.c16.

get32bitcounter¶

function get32bitcounter : uint32;

Returns the 32-bit system tick counter from arch.x86.bda.Counters.c32.

get64bitcounter¶

function get64bitcounter : uint64;

Returns the 64-bit system tick counter from arch.x86.bda.Counters.c64.

getTSC¶

function getTSC : uint64;

Reads the Time-Stamp Counter using the RDTSC instruction and returns the 64-bit result.

div6432¶

function div6432(dividend : uint64; divisor : uint32) : uint64;

Performs an unsigned 64-by-32 division using two 32-bit DIV instructions. Returns the 64-bit quotient. Used internally by MsSinceSystemBoot.

MsSinceSystemBoot¶

function MsSinceSystemBoot : uint64;

Returns the number of milliseconds elapsed since boot, computed as TSC / (CPU_Hz / 1000).

getESP¶

function getESP : uint32;

Returns the current stack pointer value.

RolDWord¶

function RolDWord(AValue : uint32; Dist : uint8) : uint32;

Rotates AValue left by Dist bit positions using the x86 ROL instruction iteratively.

RorDWord¶

function RorDWord(AValue : uint32; Dist : uint8) : uint32;

Rotates AValue right by Dist bit positions using the x86 ROR instruction iteratively.

resetSystem¶

procedure resetSystem();

Performs a hardware reset by pulsing the keyboard controller reset line (port $64, command $FE). Disables interrupts before issuing the command, then calls halt_and_catch_fire as a fallback if the reset does not take effect immediately.

Notes¶

All port I/O procedures call io_wait after the port operation. Code that needs maximum throughput (e.g., bulk PIO transfers) should call the underlying assembly directly rather than using these wrappers.
psleep is intended only for early boot hardware initialisation. Once the scheduler is running, use proper blocking mechanisms rather than busy-waiting.