pc.c.rtf

us/osII最新解读

                                                   PC.H
*********************************************************************************************************
*                                               CONSTANTS
*                                    COLOR ATTRIBUTES FOR VGA MONITOR
*Description: These #defines are used in the PC_Disp???() functions.  The 'color' argument in these
*              function MUST specify a 'foreground' color, a 'background' and whether the display will
*              blink or not.  If you don't specify a background color, BLACK is assumed.  You would 
*              specify a color combination as follows:
*              PC_DispChar(0, 0, 'A', DISP_FGND_WHITE + DISP_BGND_BLUE + DISP_BLINK);
*             To have the ASCII character 'A' blink with a white letter on a blue background.
*********************************************************************************************************
#define DISP_FGND_BLACK           0x00
#define DISP_FGND_BLUE            0x01
#define DISP_FGND_GREEN           0x02
#define DISP_FGND_CYAN            0x03
#define DISP_FGND_RED             0x04
#define DISP_FGND_PURPLE          0x05
#define DISP_FGND_BROWN           0x06
#define DISP_FGND_LIGHT_GRAY      0x07
#define DISP_FGND_DARK_GRAY       0x08
#define DISP_FGND_LIGHT_BLUE      0x09
#define DISP_FGND_LIGHT_GREEN     0x0A
#define DISP_FGND_LIGHT_CYAN      0x0B
#define DISP_FGND_LIGHT_RED       0x0C
#define DISP_FGND_LIGHT_PURPLE    0x0D
#define DISP_FGND_YELLOW          0x0E
#define DISP_FGND_WHITE           0x0F

#define DISP_BGND_BLACK           0x00
#define DISP_BGND_BLUE            0x10
#define DISP_BGND_GREEN           0x20
#define DISP_BGND_CYAN            0x30
#define DISP_BGND_RED             0x40
#define DISP_BGND_PURPLE          0x50
#define DISP_BGND_BROWN           0x60
#define DISP_BGND_LIGHT_GRAY      0x70

#define DISP_BLINK                0x80

void    PC_DispClrScr(INT8U bgnd_color);
void    PC_DispClrLine(INT8U y, INT8U bgnd_color);
void    PC_DispChar(INT8U x, INT8U y, INT8U c, INT8U color);
void    PC_DispStr(INT8U x, INT8U y, INT8U *s, INT8U color);
void    PC_DOSReturn(void);
void    PC_DOSSaveReturn(void);
void    PC_ElapsedInit(void);
void    PC_ElapsedStart(void);
INT16U  PC_ElapsedStop(void);
void    PC_GetDateTime(char *s);
BOOLEAN PC_GetKey(INT16S *c);
void    PC_SetTickRate(INT16U freq);
void   *PC_VectGet(INT8U vect);
void    PC_VectSet(INT8U vect, void (*isr)(void));

                                                     PC.C
#include "includes.h"

#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                    */

static INT16U    PC_ElapsedOverhead;
static jmp_buf   PC_JumpBuf;
static BOOLEAN   PC_ExitFlag;
void           (*PC_TickISR)(void);
*********************************************************************************************************
*                                              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)
*********************************************************************************************************
void PC_DispClrScr (INT8U color)
{
    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              */
    }
}
*********************************************************************************************************
*                                             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)
**********************************************************************************************************
void PC_DispClrLine (INT8U y, INT8U color)
{
    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                   */
    }
}
*********************************************************************************************************
*                           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.
*
*********************************************************************************************************
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    = MK_FP(DISP_BASE, offset);
    *pscr++ = c;                                           /* Put character in video RAM               */
    *pscr   = color;                                       /* Put video attribute in video RAM         */
}
*********************************************************************************************************
*                                 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.
**********************************************************************************************************
void PC_DispStr (INT8U x, INT8U y, INT8U *s, INT8U color)
{
    INT8U  far *pscr;
    INT16U      offset;
    offset  = (INT16U)y * DISP_MAX_X * 2 + (INT16U)x * 2;   /* Calculate position of 1st character     */
    pscr    = MK_FP(DISP_BASE, offset);
    while (*s) {
        *pscr++ = *s++;                                     /* Put character in video RAM              */
        *pscr++ = color;                                    /* Put video attribute in video RAM        */
    }
}
*********************************************************************************************************
*                                             RETURN TO DOS
*Description : This functions returns control back to DOS by doing a 'long jump' back to the saved
*               location stored in 'PC_JumpBuf'.  The saved location was established by the function
*               'PC_DOSSaveReturn()'.  After execution of the long jump, execution will resume at the 
*               line following the 'set jump' back in 'PC_DOSSaveReturn()'.  Setting the flag