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u32int kmalloc(u32int sz)
{
  u32int tmp = placement_address;
  placement_address += sz;
  return tmp;
}

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void initialise_paging()
{
  
   /*
    *  0x1000000 =  16777216 Byte = 16384 KiB
    */
   u32int mem_end_page = 0x1000000; // 16777216 byte

   nframes = mem_end_page / 0x1000; // (16777216 byte) / (4096 byte page/frame size)  = 4096 page/frame

   
   /*
    * nframes = 4096   
    * --> INDEX_FROM_BIT(nframes)   = 128 byte . kmalloc() 1 byte allocation.
    *  
    * frames bitmap = 4096 bits should be ,because frame count is 4096.
    *
    *  128 byte from kmalloc() , 128 byte * (1 byte = 8 bit) = total bit is 1024.
    *
    *  (u32int*)kmalloc(INDEX_FROM_BIT(nframes))  = false
    *  I think, (u32int*)kmalloc(INDEX_FROM_BIT(nframes * 4))  should be
    */ 
   frames = (u32int*)kmalloc(INDEX_FROM_BIT(nframes));
   memset(frames, 0, INDEX_FROM_BIT(nframes));
 ...
}