tabs/kernel/kernel.c

/* Check if the compiler thinks you are targeting the wrong operating system. */
#if defined(__linux__)
#error "You are not using a cross-compiler, you will most certainly run into trouble"
#endif

/* This tutorial will only work for the 32-bit ix86 targets. */
#if !defined(__i386__)
#error "This kernel needs to be compiled with a ix86-elf compiler"
#endif

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#include "terminal.c"
#include "memory.c"
#include "interrupts.c"
#include "shell.c"
#include "util/printer.c"

static inline bool are_interrupts_enabled() {
    unsigned long flags;
    asm volatile ( "pushf\n\t"
                   "pop %0"
    : "=g"(flags));
    return flags & (1 << 9);
}

void kernel_main(void) {
    /* Initialize terminal interface */
    terminal_initialize();

    terminal_putchar('H');
    terminal_putchar('e');
    terminal_putchar('l');
    terminal_putchar('l');
    terminal_putchar('o');

    terminal_setcolor(vga_entry_color(VGA_COLOR_GREEN, VGA_COLOR_BLACK));
    print(" kernel");
    terminal_setcolor(vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK));
    print(" World!\n");
    print("Newlines!\n");

    char *memory_str = alloc(sizeof(char) * 7);
    for (int i = 0; i < 6; i++) {
        memory_str[i] = "Memory"[i];
    }
    memory_str[6] = 0;

    char *management_str = alloc(sizeof(char) * 13);
    for (int i = 0; i < 13; i++) {
        management_str[i] = " management!\n"[i];
    }
    management_str[13] = 0;

    print(memory_str);
    print(management_str);

    free(memory_str);
    free(management_str);

    // Some dummy allocations to demonstrate the states of memory and to showcase the memory dump printout.
    void* ptr = alloc(30);
    alloc(30);
    alloc(31);
    free(ptr);

    void* ptr2 = alloc(64);
    alloc(61);
    free(ptr2);

    print((are_interrupts_enabled()) ? "Interrupts!\n" : "No interrupts :(\n");

    interrupt_init();

    print_memory();

    for (;;) {
        shell_step();
    }
}