/* 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;
 }