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/*
* VBMouse - Interface to the Virtual DMA Service (VDS)
* Copyright (C) 2022 Javier S. Pedro
*
* 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; either version 2
* of the License, or (at your option) any later version.
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef VDS_H
#define VDS_H
#include <stdbool.h>
#include <stdint.h>
typedef unsigned char vdserr;
enum {
VDS_SUCCESSFUL = 0,
VDS_REGION_NOT_CONTIGUOUS = 1,
VDS_REGION_NOT_ALIGNED = 2,
VDS_UNABLE_TO_LOCK = 3,
VDS_NO_BUFFER_AVAIL = 4,
VDS_REGION_TOO_LARGE = 5,
VDS_BUFFER_IN_USE = 6,
VDS_INVALID_REGION = 7,
VDS_REGION_NOT_LOCKED = 8,
VDS_TOO_MANY_PAGES = 9,
VDS_INVALID_BUFFER_ID = 0xA,
VDS_BUFFER_BOUNDARY = 0xB,
VDS_INVALID_DMA_CHANNEL = 0xC,
VDS_DISABLE_COUNT_OVRFLOW = 0xD,
VDS_DISABLE_COUNT_UNDFLOW = 0xE,
VDS_NOT_SUPPORTED = 0xF,
VDS_FLAGS_NOT_SUPPORTED = 0x10,
};
enum {
/*
Bit 1 = Automatically copy to/from buffer
Bit 2 = Disable automatic buffer allocation
Bit 3 = Disable automatic remap feature
Bit 4 = Region must not cross 64K physical alignment boundary
Bit 5 = Region must not cross 128K physical alignment boundary
Bit 6 = Copy page-table for scatter/gather remap
Bit 7 = Allow non-present pages for scatter/gather remap
*/
VDS_AUTO_COPY_DATA = 1 << 1,
VDS_NO_AUTO_ALLOC = 1 << 2,
VDS_NO_AUTO_REMAP = 1 << 3,
VDS_ALIGN_64K = 1 << 4,
VDS_ALIGN_128K = 1 << 5
};
/** DMA Descriptor structure. Describes a potentially DMA-lockable buffer. */
typedef _Packed struct VDS_DDS
{
/** Size of this buffer. */
uint32_t regionSize;
/** Logical/segmented address of this buffer, offset part */
uint32_t offset;
/** Segment of this buffer. */
uint16_t segOrSelector;
/** Internal VDS buffer ID. */
uint16_t bufferId;
/** Physical address of this buffer. */
uint32_t physicalAddress;
} VDS_DDS;
static bool vds_available(void);
#pragma aux vds_available = \
"mov ax, 0x40" \
"mov es, ax" \
"mov al, es:[0x7B]" \
"and al, 0x20" \
"setnz al" \
__value [al] \
__modify [ax es]
/** Locks an already allocated buffer into a physical memory location.
* regionSize, offset and segment must be valid in the DDS,
* while the physical address is returned. */
static vdserr vds_lock_dma_buffer_region(VDS_DDS __far * dds, unsigned char flags);
#pragma aux vds_lock_dma_buffer_region = \
"stc" /* If nothing happens, assume failure. */ \
"mov ax, 0x8103" \
"int 0x4B" \
"jc fail" \
"mov al, 0" \
"jmp end" \
"fail: test al, al" \
"jnz end" \
"mov al, 0xFF" /* Force a error code if there was none. */ \
"end:" \
__parm [es di] [dx] \
__value [al] \
__modify [ax]
/** Unlocks a locked buffer. */
static vdserr vds_unlock_dma_buffer_region(VDS_DDS __far * dds, unsigned char flags);
#pragma aux vds_unlock_dma_buffer_region = \
"stc" \
"mov ax, 0x8104" \
"int 0x4B" \
"jc fail" \
"mov al, 0" \
"jmp end" \
"fail: test al, al" \
"jnz end" \
"mov al, 0xFF" \
"end:" \
__parm [es di] [dx] \
__value [al] \
__modify [ax]
#endif
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