/*
 * Copyright (c) 2026, Apollo Telephone Laboratories.
 * Provided under the BSD-3 clause.
 */

    .text
    .code16
    .globl _start
_start:
    cli
    xor %ax, %ax
    mov %ax, %ds
    mov %ax, %es
    mov %ax, %ss

    lgdt gdtr
    mov %cr0, %eax
    or $1, %eax
    mov %eax, %cr0
    ljmp $0x08,$1f

    .code32
1:  mov $0x10, %ax
    mov %ax, %es
    mov %ax, %ss
    mov %ax, %fs
    mov %ax, %gs
    mov %ax, %ds
    jmp c_thunk

gdt:
.null:
    .quad 0
.code:
    .word 0xFFFF
    .word 0x0000
    .byte 0x00
    .byte 0b10011010
    .byte 0b11001111
    .byte 0x00
.data:
    .word 0xFFFF
    .word 0x0000
    .byte 0x00
    .byte 0b10010010
    .byte 0b11001111
    .byte 0x00
gdtr:
    .word . - gdt - 1
    .long gdt

/* Fall-through : everything above this */
c_thunk:
    nop