#pragma option -3
#include <dos.h>
#include "biosl.h"
#define NULL (void *)(0)

static int read_config_area(byte function,
				   byte bus_number,
				   byte device_and_function,
				   byte register_number,
				   dword *data);

int pci_bios_present(byte *hardware_mechanism,
			         word *interface_level_version,
			         byte *last_pci_bus_number)
{
   int ret_status;          /* Function Return Status. */
   byte bios_present_status;/* Indicates if PCI bios present */
   dword pci_signature;     /* PCI Signature ('P', 'C', 'I', ' ') */
   word ax, bx, cx, flags;  /* Temporary variables to hold register values */

   /* Load entry registers for PCI BIOS */
   _AH = PCI_FUNCTION_ID;
   _AL = PCI_BIOS_PRESENT;

   /* Call PCI BIOS Int 1Ah interface */
   geninterrupt(0x1a);

   /* Save registers before overwritten by compiler usage of registers */
   ax = _AX;
   bx = _BX;
   cx = _CX;
   pci_signature = _EDX;
   flags = _FLAGS;
   bios_present_status = HIGH_BYTE(ax);


   /* First check if CARRY FLAG Set, if so, BIOS not present */
   if ((flags & CARRY_FLAG) == 0)
   {
      /* Next, must check that AH (BIOS Present Status) == 0 */
      if (bios_present_status == 0)
      {
        /* Check bytes in pci_signature for PCI Signature */
        if ((pci_signature & 0xff)         == 'P' &&
            ((pci_signature >> 8) & 0xff)  == 'C' &&
            ((pci_signature >> 16) & 0xff) == 'I' &&
            ((pci_signature >> 24) & 0xff) == ' ')
        {
            /* Indicate to caller that PCI bios present */
            ret_status = SUCCESSFUL;

            /* Extract calling parameters from saved registers */
            if (hardware_mechanism != NULL)
                *hardware_mechanism = LOW_BYTE(ax);
            if (interface_level_version != NULL)
                *interface_level_version = bx;
            if (last_pci_bus_number != NULL)
                *last_pci_bus_number = LOW_BYTE(cx);
    	 }
      }
      else
	    ret_status = NOT_SUCCESSFUL;
   }
   else
      ret_status = NOT_SUCCESSFUL;

   return (ret_status);
}

int find_pci_device(word device_id,
		    word vendor_id,
		    word index,
		    byte *bus_number,
		    byte *device_and_function)
{
   int ret_status;     /* Function Return Status */
   word ax, bx, flags; /* Temporary variables to hold register values */

   /* Load entry registers for PCI BIOS */
   _CX = device_id;
   _DX = vendor_id;
   _SI = index;
   _AH = PCI_FUNCTION_ID;
   _AL = FIND_PCI_DEVICE;

   /* Call PCI BIOS Int 1Ah interface */
   geninterrupt(0x1a);

   /* Save registers before overwritten by compiler usage of registers */
   ax = _AX;
   bx = _BX;
   flags = _FLAGS;

   /* First check if CARRY FLAG Set, if so, error has occurred */
   if ((flags & CARRY_FLAG) == 0)
   {
      /* Get Return code from BIOS */
      ret_status = HIGH_BYTE(ax);
      if (ret_status == SUCCESSFUL)
      {
         /* Assign Bus Number, Device & Function if successful */
         if (bus_number != NULL)
            *bus_number = HIGH_BYTE(bx);
         if (device_and_function != NULL)
            *device_and_function = LOW_BYTE(bx);
      }
   }
   else
     ret_status = NOT_SUCCESSFUL;

   return (ret_status);
}

int read_config_word(byte bus_number,
			    byte device_and_function,
			    byte register_number,
			    word *word_read)
{
   int ret_status; /* Function Return Status */
   dword data;

   /* Call read_config_area function with word data */
   ret_status = read_config_area(READ_CONFIG_WORD,
					bus_number,
					device_and_function,
					register_number,
					&data);
   if (ret_status == SUCCESSFUL)
   {
      /* Extract word */
      *word_read = (word)(data & 0xffff);
   }

   return (ret_status);
}
static int read_config_area(byte function,
				   byte bus_number,
				   byte device_and_function,
				   byte register_number,
				   dword *data)
{
   int ret_status; /* Function Return Status */
   word ax, flags; /* Temporary variables to hold register values */
   dword ecx;      /* Temporary variable to hold ECX register value */

   /* Load entry registers for PCI BIOS */
   _BH = bus_number;
   _BL = device_and_function;
   _DI = register_number;
   _AH = PCI_FUNCTION_ID;
   _AL = function;

   /* Call PCI BIOS Int 1Ah interface */
   geninterrupt(0x1a);

   /* Save registers before overwritten by compiler usage of registers */
   ecx = _ECX;
   ax = _AX;
   flags = _FLAGS;

   /* First check if CARRY FLAG Set, if so, error has occurred */
   if ((flags & CARRY_FLAG) == 0)
   {
      /* Get Return code from BIOS */
      ret_status = HIGH_BYTE(ax);

      /* If successful, return data */
      if (ret_status == SUCCESSFUL)
    	 *data = ecx;
   }
   else
      ret_status = NOT_SUCCESSFUL;

   return (ret_status);
}