Una specie di «shell»

#include <stdio.h>
#include <kernel/os.h>
char
*gets (char *s)
{
    int i;
    //
    // Legge os.kbd.char.
    //
    for (i = 0; i < 256; i++)
      {
        while (os.kbd.key == 0)
          {
            //
            // Attende un carattere.
            //
            ;
          }
        s[i] = os.kbd.key;
        os.kbd.key = 0;
        if (s[i] == '\n')
          {
            s[i] = 0;
            break;
          }
      }   
    return s;
}

#ifndef _APP_H
#define _APP_H       1

void shell ();

#endif

#include <app/app.h>
#include <stdio.h>
#include <string.h>
#include <kernel/gdt.h>
#include <kernel/kernel.h>
#include <kernel/mm.h>
#include <kernel/multiboot.h>
void
shell (void)
{
    char command[256];
    //
    //
    //
    while (true)
      {
        printf ("# ");
        //
        // Legge un comando.
        //
        gets (command);
        //
        if (strcmp (command, "quit") == 0
            || strcmp (command, "q") == 0)
          {
            break;
          }
        else if (strcmp (command, "help") == 0
                 || strcmp (command, "h") == 0)
          {
            printf ("shell commands:\n");
            printf ("h|help         = this help\n");
            printf ("q|quit         = quit the shell\n");
            printf ("i mb|info mb   = "
                    "show multiboot info\n");
            printf ("i gdt|info gdt = show gdt\n");
            printf ("i mem|info mem = show memory map\n");
          }
        else if (strcmp (command, "info mb") == 0
                 || strcmp (command, "i mb") == 0)
          {
            mboot_show ();
          }
        else if (strcmp (command, "info gdt") == 0
                 || strcmp (command, "i gdt") == 0)
          {
            gdt_print (&os.gdtr);
          }
        else if (strcmp (command, "info mem") == 0
                 || strcmp (command, "i mem") == 0)
          {
            kernel_memory_show ();
            mm_list ();
          }
        else
          {
            printf ("[%s] unknown command: %s\n", __func__,
                    command);
          }
      }
}

#include <kernel/kernel.h>
#include <kernel/build.h>
#include <stdio.h>
#include <kernel/gdt.h>
#include <kernel/mm.h>
#include <stdlib.h>
#include <kernel/int.h>
#include <sys/syscall.h>
#include <kernel/timer.h>
#include <kernel/keyboard.h>
#include <app/app.h>
//
// Funzione principale, da dove si avvia il kernel.
//
void
kernel_main (unsigned long magic, multiboot_t *info)
{
    //
    // Inizializza i dati relativi alla gestione dello
    // schermo VGA, quindi ripulisce lo schermo.
    //
    vga_init ();
    clear ();
    //
    // Data e orario di compilazione.
    //
    printf ("05 %s\n", BUILD_DATE);
    //
    // Cerca le informazioni «multiboot».
    //
    if (magic == 0x2BADB002)
      {
        //
        // Salva e mostra le informazioni multiboot.
        //
        mboot_info (info);
        mboot_show ();
        //
        // Raccoglie i dati sulla memoria fisica.
        //
        kernel_memory (info);
        //
        // Predispone la tabella GDT.
        //
        gdt ();
        //
        // Predispone la memoria libera per l'utilizzo.
        //
        mm_init ();
        //
        // Predispone il timer.
        //
        timer_freq (CLOCKS_PER_SEC);
        //
        // Predispone la tastiera.
        //
        keyboard_load ();
        echo ();
        //
        // Predispone la tabella IDT.
        //
        idt();
      }
    else
      {
        printf ("[%s] no \"multiboot\" header!\n",
                __func__);
      }
    //
    // Shell.
    //
    shell ();
    //
    printf ("[%s] system halted\n", __func__);
    _Exit (0);
}

# help
shell commands:
h|help         = this help
q|quit         = quit the shell
i mb|info mb   = show multiboot info
i gdt|info gdt = show gdt
i mem|info mem = show memory map
# info mb
[mboot_show] flags: 00000000000000000000011111100111 mlow: 027F mhigh: 00007BC0
[mboot_show] bootdev: 00FFFFFF cmdline: "(fd0)/kernel"
# info gdt
[gdt_print] base: 0x0010E068 limit: 0x0017
[gdt_print] 0 00000000000000000000000000000000 00000000010000000001000000000000
[gdt_print] 1 00000000000000000001111011110000 00000000110000001001101000000000
[gdt_print] 2 00000000000000000001111011110000 00000000110000001001001100000000
# info em...
[shell] unknown command: info em...
# info mem
[kernel_memory_show] kernel 00100000..0010E5A4  avail. 0010E5A4..01EF0000
[kernel_memory_show] text   00100000..001058F4  rodata 00105900..0010600C
[kernel_memory_show] data   0010600C..0010600C  bss    00106020..0010E5A4
[kernel_memory_show] limit  00001EF0
[mm_list] free 0010E5A8..01EF0000 size 01EEFFFC
# quit
[kernel_main] system halted