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/****************************************************************************
*
* SciTech OS Portability Manager Library
*
* ========================================================================
*
* The contents of this file are subject to the SciTech MGL Public
* License Version 1.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.scitechsoft.com/mgl-license.txt
*
* Software distributed under the License is distributed on an
* "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is Copyright (C) 1991-1998 SciTech Software, Inc.
*
* The Initial Developer of the Original Code is SciTech Software, Inc.
* All Rights Reserved.
*
* ========================================================================
*
* Language: ANSI C
* Environment: 32-bit DOS
*
* Description: Main C module for the VFlat framebuffer routines. The page
* fault handler is always installed to handle up to a 4Mb
* framebuffer with a window size of 4Kb or 64Kb in size.
*
****************************************************************************/
#include "pmapi.h"
#include <stdlib.h>
#include <dos.h>
/*-------------------------------------------------------------------------*/
/* DOS4G/W, PMODE/W and CauseWay support. */
/*-------------------------------------------------------------------------*/
#if defined(DOS4GW)
#define VFLAT_START_ADDR 0xF0000000U
#define VFLAT_END_ADDR 0xF03FFFFFU
#define VFLAT_LIMIT (VFLAT_END_ADDR - VFLAT_START_ADDR)
#define PAGE_PRESENT 1
#define PAGE_NOTPRESENT 0
#define PAGE_READ 0
#define PAGE_WRITE 2
PRIVATE ibool installed = false;
PRIVATE ibool haveDPMI = false;
PUBLIC ibool _ASMAPI VF_haveCauseWay = false;
PUBLIC uchar * _ASMAPI VF_zeroPtr = NULL;
/* Low level assembler code */
int _ASMAPI InitPaging(void);
void _ASMAPI ClosePaging(void);
void _ASMAPI MapPhysical2Linear(ulong pAddr, ulong lAddr, int pages, int flags);
void _ASMAPI InstallFaultHandler(ulong baseAddr,int bankSize);
void _ASMAPI RemoveFaultHandler(void);
void _ASMAPI InstallBankFunc(int codeLen,void *bankFunc);
void * _ASMAPI VF_malloc(uint size)
{ return PM_malloc(size); }
void _ASMAPI VF_free(void *p)
{ PM_free(p); }
PRIVATE ibool CheckDPMI(void)
/****************************************************************************
*
* Function: CheckDPMI
* Returns: True if we are running under DPMI
*
****************************************************************************/
{
PMREGS regs;
if (haveDPMI)
return true;
/* Check if we are running under DPMI in which case we will not be
* able to install our page fault handlers. We can however use the
* DVA.386 or VFLATD.386 virtual device drivers if they are present.
*/
regs.x.ax = 0xFF00;
PM_int386(0x31,®s,®s);
if (!regs.x.cflag && (regs.e.edi & 8))
return (haveDPMI = true);
return false;
}
ibool PMAPI VF_available(void)
/****************************************************************************
*
* Function: VF_available
* Returns: True if virtual buffer is available, false if not.
*
****************************************************************************/
{
if (!VF_zeroPtr)
VF_zeroPtr = PM_mapPhysicalAddr(0,0xFFFFFFFF,true);
if (CheckDPMI())
return false;
/* Standard DOS4GW, PMODE/W and Causeway */
if (InitPaging() == -1)
return false;
ClosePaging();
return true;
}
void * PMAPI InitDPMI(ulong baseAddr,int bankSize,int codeLen,void *bankFunc)
/****************************************************************************
*
* Function: InitDOS4GW
* Parameters: baseAddr - Base address of framebuffer bank window
* bankSize - Physical size of banks in Kb (4 or 64)
* codeLen - Length of 32 bit bank switch function
* bankFunc - Pointer to protected mode bank function
* Returns: Near pointer to virtual framebuffer, or NULL on failure.
*
* Description: Installs the virtual linear framebuffer handling for
* DPMI environments. This requires the DVA.386 or VFLATD.386
* virtual device drivers to be installed and functioning.
*
****************************************************************************/
{
(void)baseAddr;
(void)bankSize;
(void)codeLen;
(void)bankFunc;
return NULL;
}
void * PMAPI InitDOS4GW(ulong baseAddr,int bankSize,int codeLen,void *bankFunc)
/****************************************************************************
*
* Function: InitDOS4GW
* Parameters: baseAddr - Base address of framebuffer bank window
* bankSize - Physical size of banks in Kb (4 or 64)
* codeLen - Length of 32 bit bank switch function
* bankFunc - Pointer to protected mode bank function
* Returns: Near pointer to virtual framebuffer, or NULL on failure.
*
* Description: Installs the virtual linear framebuffer handling for
* the DOS4GW extender.
*
****************************************************************************/
{
int i;
if (InitPaging() == -1)
return NULL; /* Cannot do hardware paging! */
/* Map 4MB of video memory into linear address space (read/write) */
if (bankSize == 64) {
for (i = 0; i < 64; i++) {
MapPhysical2Linear(baseAddr,VFLAT_START_ADDR+(i<<16),16,
PAGE_WRITE | PAGE_NOTPRESENT);
}
}
else {
for (i = 0; i < 1024; i++) {
MapPhysical2Linear(baseAddr,VFLAT_START_ADDR+(i<<12),1,
PAGE_WRITE | PAGE_NOTPRESENT);
}
}
/* Install our page fault handler and banks switch function */
InstallFaultHandler(baseAddr,bankSize);
InstallBankFunc(codeLen,bankFunc);
installed = true;
return (void*)VFLAT_START_ADDR;
}
void * PMAPI VF_init(ulong baseAddr,int bankSize,int codeLen,void *bankFunc)
/****************************************************************************
*
* Function: VF_init
* Parameters: baseAddr - Base address of framebuffer bank window
* bankSize - Physical size of banks in Kb (4 or 64)
* codeLen - Length of 32 bit bank switch function
* bankFunc - Pointer to protected mode bank function
* Returns: Near pointer to virtual framebuffer, or NULL on failure.
*
* Description: Installs the virtual linear framebuffer handling.
*
****************************************************************************/
{
if (installed)
return (void*)VFLAT_START_ADDR;
if (codeLen > 100)
return NULL; /* Bank function is too large! */
if (!VF_zeroPtr)
VF_zeroPtr = PM_mapPhysicalAddr(0,0xFFFFFFFF,true);
if (CheckDPMI())
return InitDPMI(baseAddr,bankSize,codeLen,bankFunc);
return InitDOS4GW(baseAddr,bankSize,codeLen,bankFunc);
}
void PMAPI VF_exit(void)
/****************************************************************************
*
* Function: VF_exit
*
* Description: Closes down the virtual framebuffer services and
* restores the previous page fault handler.
*
****************************************************************************/
{
if (installed) {
if (haveDPMI) {
/* DPMI support */
}
else {
/* Standard DOS4GW and PMODE/W support */
RemoveFaultHandler();
ClosePaging();
}
installed = false;
}
}
/*-------------------------------------------------------------------------*/
/* Support mapped out for other compilers. */
/*-------------------------------------------------------------------------*/
#else
ibool PMAPI VF_available(void)
{
return false;
}
void * PMAPI VF_init(ulong baseAddr,int bankSize,int codeLen,void *bankFunc)
{
(void)baseAddr;
(void)bankSize;
(void)codeLen;
(void)bankFunc;
return NULL;
}
void PMAPI VF_exit(void)
{
}
#endif
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