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 #define _pcie_base_addr_strct_size 16
 typedef struct pcie_confaddr_s
 {
	 uint64 *base_addr; //8 bytes base addr
	 uint16 seg_grp_num; //2 bytes segment group addr
	 uint8 bus_num_s; //stating bus number
	 uint8 bus_num_e; //ending bus number
	 uint32 reserved; //reserved
 }__attribute__((packed)) pcie_confaddr_t;

  typedef struct sdt_header_s
  {
	  char signature[4];
	  uint32 len;
	  uint8 revision;
	  uint8 checksum;
	  char OEMID[6];
	  char OEMtableID[8];
	  uint32 OEMrevision;
	  uint32 creatorID;
	  uint32 creatorRevision;
  }__attribute__((packed))sdt_header_t;


sdt_header_t *acpi_getsdt(char *sig)
{
	return acpi_findsdt(xsdt,sig);
}

sdt_header_t *acpi_findsdt(xsdt_t *_xsdt, char *signature)
{
	int i=0;sdt_header_t *tmp;
	for(i=0;i<22;i++)
	{
		tmp=(sdt_header_t *)_ptr_conv _xsdt->other_tables[i];
		if(strncmp(tmp->signature,signature,4)==0)
		  if(bytesum((phys_addr *)_ptr_conv tmp,tmp->len)==0)
		    return tmp;				
	}
	return (sdt_header_t *)0;
}


void pcie_init()
{
	sdt_header_t *mcfg=acpi_getsdt("MCFG");
	printf("\n\t Locating PCI Express Extended configuration space");
	if(!mcfg)
	{
		mcfg=mcfg_pci;
		if(!mcfg)
		{
			mprintf(error_text_colour,"\n\t Unable to locate PCI Express Extended configuration space");
			return;
		}		
	}
	if(((bytesum((phys_addr *) _ptr_conv mcfg,mcfg->len))&0xff)!=0)
	{		
		mcfg=mcfg_pci;
		if(!mcfg || (((bytesum((phys_addr *) _ptr_conv mcfg,mcfg->len))&0xff)!=0))
		{
			mprintf(error_text_colour,"\n\t Invalid ACPI MCFG Table");
			return;
		}
	}
	bus_range[0]=(pcie_confaddr_t *)mcfg+(mcfg->len);
	printf("\n\t Found buses from : %d-%d ,",bus_range[0]->bus_num_s,bus_range[0]->bus_num_e);
	pcie_find_bus_ranges(mcfg);
}
void pcie_find_bus_ranges(sdt_header_t *mcfg)
{
	int i=0;
	bus_range[0]=(pcie_confaddr_t *)mcfg+(mcfg->len);
	i=0;
	while(i<51)
	{
		++i;
		bus_range[i]=bus_range[0]+(_pcie_base_addr_strct_size*i);
		printf(" %d-%d ,",bus_range[i]->bus_num_s,bus_range[i]->bus_num_e);
	}
}