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/* $Id: vds.c $ */
/** @file
* Utility routines for calling the Virtual DMA Services.
*/
/*
* Copyright (C) 2011-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#include <stdint.h>
#include "biosint.h"
#include "vds.h"
typedef struct {
uint8_t major; /* VDS spec major version number. */
uint8_t minor; /* VDS spec minor version number. */
uint16_t flags; /* Capabilities/status flags. */
uint16_t prod_no; /* Product number. */
uint16_t prod_rev; /* Product revision number. */
uint32_t max_buf; /* Maximum buffer size supported. */
} vds_ver;
int vds_is_present( void )
{
uint8_t __far *vds_flags;
vds_flags = MK_FP( 0x40, VDS_FLAGS_OFS );
return( !!(*vds_flags & VDS_PRESENT) );
}
int vds_lock_sg( vds_edds __far *edds );
#pragma aux vds_lock_sg = \
"mov ax, 8105h" \
"mov dx, 0" \
"int 4Bh" \
"jc error" \
"xor al, al" \
"error:" \
"cbw" \
parm [es di] value [ax];
int vds_unlock_sg( vds_edds __far *edds );
#pragma aux vds_unlock_sg = \
"mov ax, 8106h" \
"mov dx, 0" \
"int 4Bh" \
"jc error" \
"xor al, al" \
"error:" \
"cbw" \
parm [es di] value [ax];
/*
* Convert a real mode 16:16 segmented address to a simple 32-bit
* linear address.
*/
uint32_t vds_real_to_lin( void __far *ptr )
{
return( ((uint32_t)FP_SEG( ptr ) << 4) + FP_OFF( ptr ) );
}
/*
* Build a VDS-style scatter/gather list, regardless of whether VDS is
* present or not. This routine either calls VDS to do the work or
* trivially creates the list if no remapping is needed.
*/
int vds_build_sg_list( vds_edds __far *edds, void __far *buf, uint32_t len )
{
int rc;
/* NB: The num_avail field in the EDDS must be set correctly! */
edds->region_size = len;
edds->offset = vds_real_to_lin( buf );
edds->seg_sel = 0; /* Indicates a linear address. */
if( vds_is_present() ) {
/* VDS is present, use it. */
rc = vds_lock_sg( edds );
} else {
/* No VDS, do it ourselves with one S/G entry. */
edds->num_used = 1;
edds->u.sg[0].phys_addr = edds->offset;
edds->u.sg[0].size = len;
rc = VDS_SUCCESS;
}
return( rc );
}
/*
* Free a VDS-style scatter/gather list, regardless of whether VDS
* is present or not.
*/
int vds_free_sg_list( vds_edds __far *edds )
{
int rc;
if( vds_is_present() ) {
/* VDS is present, use it. */
rc = vds_unlock_sg( edds );
} else {
/* No VDS, not much to do. */
/* We could check here if the EDDS had in fact been built by us.
* But if VDS really went away, what can we do about it anyway?
*/
rc = VDS_SUCCESS;
}
edds->num_used = 0;
return( rc );
}
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