/*
*********************************************************************************************************
*                                          PC SUPPORT FUNCTIONS
*
*                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
*                                           All Rights Reserved
*
* File : PC.C
* By   : Jean J. Labrosse
*********************************************************************************************************
*/

#include "includes.h"
#include "pc.h"
#include "os_kc51.h"

/*
PC display by KC51 emulation
*/

#define interrupt
#define far	xdata
#define MK_FP(s, o)		((INT8U xdata *)(INT16U)(o))
#define getvect(vect)	((vect=vect),((void*)NULL))
#define setvect(vect, isr)	(vect=vect, isr=isr)
int OSTickDOSCtr;

const char code * const code ExitNotice[]=
{
	"Exit program",
	"Program has terminated",
	"Reset the processor to restart the program"
};

bit kbhit() KCREENTRANT;
INT8U getch() KCREENTRANT;

void exit(INT8U ec) KCREENTRANT
{
	static char str[64];

    OS_ENTER_CRITICAL();
	for(;;)
	{
		INT8U i;

		for(i=0; i<sizeof(ExitNotice)/sizeof(ExitNotice[0]); i++)
		{
			PC_DispStr (0, 8+i, ExitNotice[i], DISP_FGND_WHITE + DISP_BGND_BLACK);
		}
		sprintf(str, "Exit code = %bd", ec);
		PC_DispStr (0, 24, str, DISP_FGND_WHITE + DISP_BGND_BLACK);
		while(! kbhit());
		getch();
		((void(*)(void))0)();
	}

	OS_EXIT_CRITICAL();
}

INT8U inp(INT8U p)
{
    INT8U  far *pscr;
    pscr = MK_FP(DISP_BASE, 0x1000+p);
	return * pscr;
}

void outp(INT8U p, INT8U d)
{
    INT8U  far *pscr;
    pscr	= MK_FP(DISP_BASE, 0x1000+p);
	*pscr	= d;
}

struct time
{
	INT8U ti_hour, ti_min, ti_sec;
};

struct date
{
	INT8U da_year, da_mon, da_day;
};

void gettime(struct time * pti) KCREENTRANT
{
    INT8U  far *pscr;
    pscr			= MK_FP(DISP_BASE, 0x2010);
	pti->ti_hour	=* pscr ++;
	pti->ti_min		=* pscr ++;
	pti->ti_sec		=* pscr;
}

void getdate(struct date * pdt) KCREENTRANT
{
    INT8U  far *pscr;
    pscr			= MK_FP(DISP_BASE, 0x2020);
	pdt->da_year	= * pscr ++;
	pdt->da_mon		= * pscr ++;
	pdt->da_day		= * pscr;
}

/*
INT8U random(INT8U seed) KCREENTRANT
{
	INT8U xdata * p;
	p=MK_FP(0, 0x2032);
	return ((*p)^((INT16U) rand())) % (INT16U)seed;
}
*/

INT8U random(INT8U seed) KCREENTRANT
{
	return (((INT16U) rand())^((INT16U) rand())+TL0) % (INT16U)seed;
}

bit kbhit() KCREENTRANT
{
    INT8U  far *pscr;
    pscr = MK_FP(DISP_BASE, 0x2030);
	return *pscr;
}

INT8U getch() KCREENTRANT
{
    INT8U  far *pscr;
    pscr = MK_FP(DISP_BASE, 0x2031);
	return *pscr;
}

/*
*********************************************************************************************************
*                                               CONSTANTS
*********************************************************************************************************
*/
#define  DISP_BASE                  0xB800       /* Base segment of display (0xB800=VGA, 0xB000=Mono)  */
#define  DISP_MAX_X                     80       /* Maximum number of columns                          */
#define  DISP_MAX_Y                     25       /* Maximum number of rows                             */

#define  TICK_T0_8254_CWR             0x43       /* 8254 PIT Control Word Register address.            */
#define  TICK_T0_8254_CTR0            0x40       /* 8254 PIT Timer 0 Register address.                 */
#define  TICK_T0_8254_CTR1            0x41       /* 8254 PIT Timer 1 Register address.                 */
#define  TICK_T0_8254_CTR2            0x42       /* 8254 PIT Timer 2 Register address.                 */

#define  TICK_T0_8254_CTR0_MODE3      0x36       /* 8254 PIT Binary Mode 3 for Counter 0 control word. */
#define  TICK_T0_8254_CTR2_MODE0      0xB0       /* 8254 PIT Binary Mode 0 for Counter 2 control word. */
#define  TICK_T0_8254_CTR2_LATCH      0x80       /* 8254 PIT Latch command control word                */

#define  VECT_TICK                    0x08       /* Vector number for 82C54 timer tick                 */
#define  VECT_DOS_CHAIN               0x81       /* Vector number used to chain DOS                    */

/*
*********************************************************************************************************
*                                       LOCAL GLOBAL VARIABLES
*********************************************************************************************************
*/
             
static INT16U    PC_ElapsedOverhead;
static jmp_buf   PC_JumpBuf;
static BOOLEAN   PC_ExitFlag;
void           (*PC_TickISR)(void);

/*$PAGE*/
/*
*********************************************************************************************************
*                                              CLEAR SCREEN
*
* Description : This function clears the PC's screen by directly accessing video RAM instead of using
*               the BIOS.  It assumed that the video adapter is VGA compatible.  Video RAM starts at
*               absolute address 0x000B8000.  Each character on the screen is composed of two bytes:
*               the ASCII character to appear on the screen followed by a video attribute.  An attribute
*               of 0x07 displays the character in WHITE with a black background.
*
* Arguments   : color   specifies the foreground/background color combination to use 
*                       (see PC.H for available choices)
*
* Returns     : None
*********************************************************************************************************
*/
void PC_DispClrScr (INT8U color) KCREENTRANT
{
    INT8U  far *pscr;
    INT16U      i;


    pscr = MK_FP(DISP_BASE, 0x0000);
    for (i = 0; i < (DISP_MAX_X * DISP_MAX_Y); i++) { /* PC display has 80 columns and 25 lines        */
        *pscr++ = ' ';                                /* Put ' ' character in video RAM                */
        *pscr++ = color;                              /* Put video attribute in video RAM              */
    }
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                             CLEAR A LINE
*
* Description : This function clears one of the 25 lines on the PC's screen by directly accessing video 
*               RAM instead of using the BIOS.  It assumed that the video adapter is VGA compatible.  
*               Video RAM starts at absolute address 0x000B8000.  Each character on the screen is 
*               composed of two bytes: the ASCII character to appear on the screen followed by a video 
*               attribute.  An attribute of 0x07 displays the character in WHITE with a black background.
*
* Arguments   : y            corresponds to the desired line to clear.  Valid line numbers are from 
*                            0 to 24.  Line 0 corresponds to the topmost line.
*
*               color        specifies the foreground/background color combination to use 
*                            (see PC.H for available choices)
*
* Returns     : None
*********************************************************************************************************
*/
void PC_DispClrLine (INT8U y, INT8U color) KCREENTRANT
{
    INT8U far *pscr;
    INT8U      i;


    pscr = MK_FP(DISP_BASE, (INT16U)y * DISP_MAX_X * 2);
    for (i = 0; i < DISP_MAX_X; i++) {
        *pscr++ = ' ';                           /* Put ' ' character in video RAM                     */
        *pscr++ = color;                         /* Put video attribute in video RAM                   */
    }
}
/*$PAGE*/
/*
*********************************************************************************************************
*                           DISPLAY A SINGLE CHARACTER AT 'X' & 'Y' COORDINATE
*
* Description : This function writes a single character anywhere on the PC's screen.  This function
*               writes directly to video RAM instead of using the BIOS for speed reasons.  It assumed 
*               that the video adapter is VGA compatible.  Video RAM starts at absolute address 
*               0x000B8000.  Each character on the screen is composed of two bytes: the ASCII character 
*               to appear on the screen followed by a video attribute.  An attribute of 0x07 displays 
*               the character in WHITE with a black background.
*
* Arguments   : x      corresponds to the desired column on the screen.  Valid columns numbers are from
*                      0 to 79.  Column 0 corresponds to the leftmost column.
*               y      corresponds to the desired row on the screen.  Valid row numbers are from 0 to 24.
*                      Line 0 corresponds to the topmost row.
*               c      Is the ASCII character to display.  You can also specify a character with a 
*                      numeric value higher than 128.  In this case, special character based graphics
*                      will be displayed.
*               color  specifies the foreground/background color to use (see PC.H for available choices)
*                      and whether the character will blink or not.
*
* Returns     : None
*********************************************************************************************************
*/
void PC_DispChar (INT8U x, INT8U y, INT8U c, INT8U color) KCREENTRANT
{
    INT8U  far *pscr;
    INT16U      offset;


    offset  = (INT16U)y * DISP_MAX_X * 2 + (INT16U)x * 2;  /* Calculate position on the screen         */
    pscr    = MK_FP(DISP_BASE, offset);
    *pscr++ = c;                                           /* Put character in video RAM               */
    *pscr   = color;                                       /* Put video attribute in video RAM         */
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                 DISPLAY A STRING  AT 'X' & 'Y' COORDINATE
*
* Description : This function writes an ASCII string anywhere on the PC's screen.  This function writes
*               directly to video RAM instead of using the BIOS for speed reasons.  It assumed that the 
*               video adapter is VGA compatible.  Video RAM starts at absolute address 0x000B8000.  Each 
*               character on the screen is composed of two bytes: the ASCII character to appear on the 
*               screen followed by a video attribute.  An attribute of 0x07 displays the character in 
*               WHITE with a black background.
*
* Arguments   : x      corresponds to the desired column on the screen.  Valid columns numbers are from
*                      0 to 79.  Column 0 corresponds to the leftmost column.
*               y      corresponds to the desired row on the screen.  Valid row numbers are from 0 to 24.
*                      Line 0 corresponds to the topmost row.
*               s      Is the ASCII string to display.  You can also specify a string containing 
*                      characters with numeric values higher than 128.  In this case, special character 
*                      based graphics will be displayed.
*               color  specifies the foreground/background color to use (see PC.H for available choices)
*                      and whether the characters will blink or not.
*
* Returns     : None
*********************************************************************************************************
*/