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/* ********************************************************************************************************* * 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" /* ********************************************************************************************************* * 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); /*$PAGE*/ /* ********************************************************************************************************* * DISPLAY A SINGLE CHARACTER AT 'X' & 'Y' COORDINATE * * Description : This function writes a single character anywhere on the PC's screen. This function * writes directly to video RAM instead of using the BIOS for speed reasons. It assumed * that the video adapter is VGA compatible. Video RAM starts at absolute address * 0x000B8000. Each character on the screen is composed of two bytes: the ASCII character * to appear on the screen followed by a video attribute. An attribute of 0x07 displays * the character in WHITE with a black background. * * Arguments : x corresponds to the desired column on the screen. Valid columns numbers are from * 0 to 79. Column 0 corresponds to the leftmost column. * y corresponds to the desired row on the screen. Valid row numbers are from 0 to 24. * Line 0 corresponds to the topmost row. * c Is the ASCII character to display. You can also specify a character with a * numeric value higher than 128. In this case, special character based graphics * will be displayed. * color specifies the foreground/background color to use (see PC.H for available choices) * and whether the character will blink or not. * * Returns : None ********************************************************************************************************* */ void PC_DispChar (INT8U x, INT8U y, INT8U c, INT8U color) { INT8U far *pscr; INT16U offset; offset = (INT16U)y * DISP_MAX_X * 2 + (INT16U)x * 2; /* Calculate position on the screen */ pscr = (INT8U far *)MK_FP(DISP_BASE, offset); *pscr++ = c; /* Put character in video RAM */ *pscr = color; /* Put video attribute in video RAM */ } /*$PAGE*/ /* ********************************************************************************************************* * CLEAR A COLUMN * * Description : This function clears one of the 80 columns 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 : x corresponds to the desired column to clear. Valid column numbers are from * 0 to 79. Column 0 corresponds to the leftmost column. * * color specifies the foreground/background color combination to use * (see PC.H for available choices) * * Returns : None ********************************************************************************************************* */ void PC_DispClrCol (INT8U x, INT8U color) { INT8U far *pscr; INT8U i; pscr = (INT8U far *)MK_FP(DISP_BASE, (INT16U)x * 2); for (i = 0; i < DISP_MAX_Y; i++) { *pscr++ = ' '; /* Put ' ' character in video RAM */ *pscr = color; /* Put video attribute in video RAM */ pscr = pscr + DISP_MAX_X * 2; /* Position on next row */ } } /*$PAGE*/ /* ********************************************************************************************************* * CLEAR A ROW * * 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 row to clear. Valid row numbers are from * 0 to 24. Row 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_DispClrRow (INT8U y, INT8U color) { INT8U far *pscr; INT8U i; pscr = (INT8U far *)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 vi