#include "kernel.h"

multiboot_info_t *multiboot_info = 0; // Set by startup code.
uint64_t available_memory = 0;
uint64_t ramdisk_location = 0;

/* Retrieve memory information from multiboot header */
void read_multiboot_info()
{
   if ((multiboot_info->flags & (1 << 6)) == (1 << 6))
   {
      multiboot_memory_map_t *mmap;
      for (mmap = (multiboot_memory_map_t*)(uint64_t)multiboot_info->mmap_addr; 
            (uint64_t)mmap < multiboot_info->mmap_addr + multiboot_info->mmap_length; 
            mmap = (multiboot_memory_map_t*) ( (uint64_t)mmap + mmap->size + sizeof(mmap->size)) )
      {
         /*
         printf("size: %d, start: 0x%x, length=0x%x, type=%d\n", mmap->size, 
            mmap->base, mmap->length, mmap->type);
         */

         if ( (mmap->type == 1) && (mmap->base == 0x100000) )
         {
            available_memory = mmap->length;
         }
      }
   }

   if (available_memory == 0)
   {
      panic("Found no usable memory in grub's memory map\n");
   }

   if ((multiboot_info->flags & (1 << 3)) == (1 << 3))
   {
      uint64_t i;
      multiboot_module_t *mod = (multiboot_module_t*)(uint64_t)multiboot_info->mods_addr;
      for (i=0; i<multiboot_info->mods_count; i++)
      {
         // TODO: determine better way of finding the initrd module.
         if (i == 0)
         {
            ramdisk_location = mod->mod_start;
         }

         // Make sure that placement malloc does not overwrite the ramdisk.
         uint64_t new_placement = (uint64_t)mod->mod_end;
         if (new_placement > placement_address)
         {
            if ((new_placement & 0xFFF) != 0)
            {
               new_placement = (new_placement & (~0xFFF)) + 0x1000; // Align to 4 KiB page.
            }
            placement_address = new_placement;
         }
         mod++; // Go to next module.
      }
   }
}