main.c

Simple Operating Systems （简称SOS）是一个可以运行在X86平台上（包括QEMU

/* Copyright (C) 2004  The SOS Team
   Copyright (C) 1999  Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   of the License, or (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
   USA. 
*/

/* Include definitions of the multiboot standard */
#include <bootstrap/multiboot.h>
#include <hwcore/idt.h>
#include <hwcore/gdt.h>
#include <hwcore/irq.h>
#include <hwcore/exception.h>
#include <hwcore/i8254.h>
#include <sos/list.h>
#include <sos/physmem.h>
#include <sos/klibc.h>
#include <sos/assert.h>
#include <drivers/x86_videomem.h>
#include <drivers/bochs.h>


/* Helper function to display each bits of a 32bits integer on the
   screen as dark or light carrets */
static void display_bits(unsigned char row, unsigned char col,
			 unsigned char attribute,
			 sos_ui32_t integer)
{
  int i;
  /* Scan each bit of the integer, MSb first */
  for (i = 31 ; i >= 0 ; i--)
    {
      /* Test if bit i of 'integer' is set */
      int bit_i = (integer & (1 << i));
      /* Ascii 219 => dark carret, Ascii 177 => light carret */
      unsigned char ascii_code = bit_i?219:177;
      sos_x86_videomem_putchar(row, col++,
			       attribute,
			       ascii_code);
    }
}


/* Clock IRQ handler */
static void clk_it(int intid)
{
  static sos_ui32_t clock_count = 0;

  display_bits(0, 48,
	       SOS_X86_VIDEO_FG_LTGREEN | SOS_X86_VIDEO_BG_BLUE,
	       clock_count);
  clock_count++;

}

#define MY_PPAGE_NUM_INT 511
struct my_ppage
{
  sos_ui32_t before[MY_PPAGE_NUM_INT];
  struct my_ppage *prev, *next;
  sos_ui32_t after[MY_PPAGE_NUM_INT];
}; /* sizeof() Must be <= 4kB */

static void test_physmem()
{
  /* We place the pages we did allocate here */
  struct my_ppage *ppage_list, *my_ppage;
  sos_count_t num_alloc_ppages = 0, num_free_ppages = 0;

  ppage_list = NULL;
  while ((my_ppage = (struct my_ppage*)sos_physmem_ref_physpage_new(FALSE))
	 != NULL)
    {
      int i;
      num_alloc_ppages++;
      
      /* Print the allocation status */
      sos_x86_videomem_printf(2, 0,
			      SOS_X86_VIDEO_FG_YELLOW
			      | SOS_X86_VIDEO_BG_BLUE,
			      "Could allocate %d pages      ",
			      num_alloc_ppages);

      /* We fill this page with its address */
      for (i = 0 ; i < MY_PPAGE_NUM_INT ; i++)
	my_ppage->before[i] = my_ppage->after[i] = (sos_ui32_t)my_ppage;

      /* We add this page at the tail of our list of ppages */
      list_add_tail(ppage_list, my_ppage);
    }

  /* Now we release these pages in FIFO order */
  while ((my_ppage = list_pop_head(ppage_list)) != NULL)
    {
      /* We make sure this page was not overwritten by any unexpected
	 value */
      int i;
      for (i = 0 ; i < MY_PPAGE_NUM_INT ; i++)
	{
	  /* We don't get what we expect ! */
	  if ((my_ppage->before[i] !=  (sos_ui32_t)my_ppage)
	      || (my_ppage->after[i] !=  (sos_ui32_t)my_ppage))
	    {
	      /* STOP ! */
	      sos_x86_videomem_putstring(20, 0,
					 SOS_X86_VIDEO_FG_LTRED
					   | SOS_X86_VIDEO_BG_BLUE,
					 "Page overwritten");
	      return;
	    }
	}

      /* Release the descriptor */
      if (sos_physmem_unref_physpage((sos_paddr_t)my_ppage) < 0)
	{
	  /* STOP ! */
	  sos_x86_videomem_putstring(20, 0,
				     SOS_X86_VIDEO_FG_LTRED
				       | SOS_X86_VIDEO_BG_BLUE,
				     "Cannot release page");
	  return;
	}

      /* Print the deallocation status */
      num_free_ppages ++;
      sos_x86_videomem_printf(2, 0,
			      SOS_X86_VIDEO_FG_YELLOW
			      | SOS_X86_VIDEO_BG_BLUE,
			      "Could free %d pages      ",
			      num_free_ppages);
    }

  /* Print the overall stats */
  sos_x86_videomem_printf(2, 0,
			  SOS_X86_VIDEO_FG_LTGREEN
			  | SOS_X86_VIDEO_BG_BLUE,
			  "Could allocate %d bytes, could free %d bytes     ",
			  num_alloc_ppages << SOS_PAGE_SHIFT,
			  num_free_ppages << SOS_PAGE_SHIFT);

  SOS_ASSERT_FATAL(num_alloc_ppages == num_free_ppages);
}


/* The C entry point of our operating system */
void sos_main(unsigned long magic, unsigned long addr)
{
  unsigned i;
  sos_paddr_t sos_kernel_core_base_paddr, sos_kernel_core_top_paddr;

  /* Grub sends us a structure, called multiboot_info_t with a lot of
     precious informations about the system, see the multiboot
     documentation for more information. */
  multiboot_info_t *mbi;
  mbi = (multiboot_info_t *) addr;

  /* Setup bochs and console, and clear the console */
  sos_bochs_setup();

  sos_x86_videomem_setup();
  sos_x86_videomem_cls(SOS_X86_VIDEO_BG_BLUE);

  /* Greetings from SOS */
  if (magic == MULTIBOOT_BOOTLOADER_MAGIC)
    /* Loaded with Grub */
    sos_x86_videomem_printf(1, 0,
			    SOS_X86_VIDEO_FG_YELLOW | SOS_X86_VIDEO_BG_BLUE,
			    "Welcome From GRUB to %s%c RAM is %dMB (upper mem = 0x%x kB)",
			    "SOS", ',',
			    (unsigned)(mbi->mem_upper >> 10) + 1,
			    (unsigned)mbi->mem_upper);
  else
    /* Not loaded with grub */
    sos_x86_videomem_printf(1, 0,
			    SOS_X86_VIDEO_FG_YELLOW | SOS_X86_VIDEO_BG_BLUE,
			    "Welcome to SOS");

  sos_bochs_putstring("Message in a bochs\n");

  /* Setup CPU segmentation and IRQ subsystem */
  sos_gdt_setup();
  sos_idt_setup();

  /* Setup SOS IRQs and exceptions subsystem */
  sos_exceptions_setup();
  sos_irq_setup();

  /* Configure the timer so as to raise the IRQ0 at a 100Hz rate */
  sos_i8254_set_frequency(100);


  /* We need a multiboot-compliant boot loader to get the size of the RAM */
  if (magic != MULTIBOOT_BOOTLOADER_MAGIC)
    {
      sos_x86_videomem_putstring(20, 0,
				 SOS_X86_VIDEO_FG_LTRED
				   | SOS_X86_VIDEO_BG_BLUE
				   | SOS_X86_VIDEO_FG_BLINKING,
				 "I'm not loaded with Grub !");
      /* STOP ! */
      for (;;)
	continue;
    }

  /* Binding some HW interrupts and exceptions to software routines */
  sos_irq_set_routine(SOS_IRQ_TIMER,
			    clk_it);
  /* Enabling the HW interrupts here, this will make the timer HW
     interrupt call our clk_it handler */
  asm volatile ("sti\n");
  /* Multiboot says: "The value returned for upper memory is maximally
     the address of the first upper memory hole minus 1 megabyte.". It
     also adds: "It is not guaranteed to be this value." aka "YMMV" ;) */
  sos_physmem_setup((mbi->mem_upper<<10) + (1<<20),
		    & sos_kernel_core_base_paddr,
		    & sos_kernel_core_top_paddr);
  test_physmem();

  /* An operatig system never ends */
  for (;;)
    continue;

  return;
}