pnpbios.c File Reference

PnP BIOS. More...

#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <realmode.h>
#include <pnpbios.h>

Go to the source code of this file.

Data Structures
struct	pnp_bios
	PnP BIOS structure. More...
Defines
#define	PNP_BIOS_SIGNATURE   ( ( '$' << 0 ) + ( 'P' << 8 ) + ( 'n' << 16 ) + ( 'P' << 24 ) )
	Signature for a PnP BIOS structure.
Functions
	FILE_LICENCE (GPL2_OR_LATER)
static int	is_pnp_bios (unsigned int offset)
	Test address for PnP BIOS structure.
int	find_pnp_bios (void)
	Locate Plug-and-Play BIOS.
Variables
struct pnp_bios	packed
	PnP BIOS structure.

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Detailed Description

PnP BIOS.

Definition in file pnpbios.c.

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Define Documentation

#define PNP_BIOS_SIGNATURE   ( ( '$' << 0 ) + ( 'P' << 8 ) + ( 'n' << 16 ) + ( 'P' << 24 ) )

Signature for a PnP BIOS structure.

Definition at line 51 of file pnpbios.c.

Referenced by is_pnp_bios().

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Function Documentation

FILE_LICENCE

(

GPL2_OR_LATER

)

static int is_pnp_bios

(

unsigned int

offset

)

[static]

Test address for PnP BIOS structure.

Parameters:

offset

Offset within BIOS segment to test

Return values:

rc

Return status code

Definition at line 60 of file pnpbios.c.

References BIOS_SEG, copy_from_real, DBG, EINVAL, and PNP_BIOS_SIGNATURE.

Referenced by find_pnp_bios().

                                               {
        union {
                struct pnp_bios pnp_bios;
                uint8_t bytes[256]; /* 256 is maximum length possible */
        } u;
        size_t len;
        unsigned int i;
        uint8_t sum = 0;

        /* Read start of header and verify signature */
        copy_from_real ( &u.pnp_bios, BIOS_SEG, offset, sizeof ( u.pnp_bios ));
        if ( u.pnp_bios.signature != PNP_BIOS_SIGNATURE )
                return -EINVAL;

        /* Read whole header and verify checksum */
        len = u.pnp_bios.length;
        copy_from_real ( &u.bytes, BIOS_SEG, offset, len );
        for ( i = 0 ; i < len ; i++ ) {
                sum += u.bytes[i];
        }
        if ( sum != 0 )
                return -EINVAL;

        DBG ( "Found PnP BIOS at %04x:%04x\n", BIOS_SEG, offset );

        return 0;
}

int find_pnp_bios

(

void

)

Locate Plug-and-Play BIOS.

Return values:

pnp_offset

Offset of PnP BIOS structure within BIOS segment

The PnP BIOS structure will be at BIOS_SEG:pnp_offset. If no PnP BIOS is found, -1 is returned.

Definition at line 96 of file pnpbios.c.

References is_pnp_bios().

Referenced by undi_load(), and undinet_probe().

                           {
        static int pnp_offset = 0;

        if ( pnp_offset )
                return pnp_offset;

        for ( pnp_offset = 0 ; pnp_offset < 0x10000 ; pnp_offset += 0x10 ) {
                if ( is_pnp_bios ( pnp_offset ) == 0 )
                        return pnp_offset;
        }

        pnp_offset = -1;
        return pnp_offset;
}

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Variable Documentation

struct pnp_bios packed

PnP BIOS structure.