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/*------------------------------[ vhdw.c ]-----------------------------*/
/* Hardware Interface Routines */
/*---------------------------------------------------------------------
/*---------------------------------------------------------------------*/
/* This code is a subset of a library copyrighted by Jeff Dunlop. */
/* License is hereby granted for unrestricted use. */
/*---------------------------------------------------------------------*/
/*---------------------------------------------------------------------*/
/* dv_info: get video and version info about DesqView */
/* get_rows: determine number of rows on screen */
/* get_cols: determine number of columns on screen */
/* get_vidpage: determine the current text mode video page */
/* get_vidbase: determine the base of video ram */
/* is_dv: determine if DesqView is loaded */
/* is_egavga: determine if monitor is ega/vga */
/*---------------------------------------------------------------------*/
/*--------------------------------------------------------------*/
/*-----------------------[ include files ]----------------------*/
/*--------------------------------------------------------------*/
#include <dos.h>
#ifndef MK_FP
#define MK_FP(seg,offset) \
((void _far *)(((unsigned long)(seg)<<16) | (unsigned)(offset)))
#endif
typedef struct
{
int ver_major;
int ver_minor;
unsigned regen_buf;
int win_rows;
int win_cols;
} DV_INFO;
/*------------------------[ get_vidpage ]-----------------------*/
/* Determine the current text mode video page */
/*--------------------------------------------------------------*/
/* local: */
/* regs = register storage buffer */
/* return: */
/* video page number as determined by bios call */
/*--------------------------------------------------------------*/
unsigned char get_vidpage(void)
{
union REGS regs;
regs.h.ah = 0x0f;
int86(0x10, ®s, ®s);
return regs.h.bh;
}
/*---------------------------[ is_dv ]--------------------------*/
/* Determine whether DesqView is active */
/*--------------------------------------------------------------*/
int is_dv(void)
{
union REGS regs;
regs.h.ah = 0x2b;
regs.x.cx = 0x4445; /* 'DE' */
regs.x.dx = 0x5351; /* 'SQ' */
regs.h.al = 1; /* get version */
int86(0x21, ®s, ®s);
return regs.h.al != 0xff;
}
/*--------------------------[ dv_info ]-------------------------*/
/* Return screen and version info about DesqView */
/*--------------------------------------------------------------*/
/* return: */
/* -1 on error */
/*--------------------------------------------------------------*/
int get_dvinfo(DV_INFO *dv_info)
{
union REGS regs;
regs.h.ah = 0x2b;
regs.x.cx = 0x4445; /* 'DE' */
regs.x.dx = 0x5351; /* 'SQ' */
regs.h.al = 1; /* get version */
int86(0x21, ®s, ®s);
if (regs.h.al == 0xff)
return -1;
dv_info->ver_major = regs.h.bh;
dv_info->ver_minor = regs.h.bl;
regs.h.al = 4; /* get screen info */
int86(0x21, ®s, ®s);
if (regs.h.al == 0xff)
return -1;
dv_info->regen_buf = regs.x.dx;
dv_info->win_rows = regs.h.bh;
dv_info->win_cols = regs.h.bl;
return 0;
}
/*------------------------[ get_vidbase ]-----------------------*/
/* Determine the base of video ram */
/*--------------------------------------------------------------*/
/* local: */
/* regs = register union for ISR */
/* return: */
/* the current text base segment */
/*--------------------------------------------------------------*/
unsigned get_vidbase(void)
{
union REGS regs;
DV_INFO dv_info;
if (is_dv() && get_dvinfo(&dv_info) != -1)
return dv_info.regen_buf;
else
{
regs.h.ah = 0xf;
int86(0x10, ®s, ®s);
if (regs.h.al == 7)
return 0xb000;
else
return 0xb800;
}
}
/*-------------------------[ get_rows ]-------------------------*/
/* Determine the number of rows in current text mode screen */
/*--------------------------------------------------------------*/
int is_egavga(void);
int get_rows(void)
{
DV_INFO dv_info;
char far *p = MK_FP(0x40, 0x84);
if (is_dv() && get_dvinfo(&dv_info) != -1)
return dv_info.win_rows;
else
return *p + is_egavga();
}
/*-------------------------[ get_cols ]-------------------------*/
/* Determine the number of columns in current text screen */
/*--------------------------------------------------------------*/
int get_cols(void)
{
DV_INFO dv_info;
int far *p = MK_FP(0x40, 0x4a);
if (is_dv() && get_dvinfo(&dv_info) != -1)
return dv_info.win_cols;
else
return *p;
}
/*-------------------------[ is_egavga ]------------------------*/
/* Determine whether the current text mode is ega/vga */
/*--------------------------------------------------------------*/
int is_egavga(void)
{
union REGS regs;
regs.h.ah = 0x1a;
regs.h.al = 0;
int86(0x10, ®s, ®s);
return regs.h.al == 0x1a;
}
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