vga.c File Reference

#include "devices/vga.h"
#include <round.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include "threads/io.h"
#include "threads/interrupt.h"
#include "threads/vaddr.h"

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Macros
#define	COL_CNT   80
#define	ROW_CNT   25
#define	GRAY_ON_BLACK   0x07

Functions
static void	clear_row (size_t y)
static void	cls (void)
static void	newline (void)
static void	move_cursor (void)
static void	find_cursor (size_t *x, size_t *y)
static void	init (void)
void	vga_putc (int c)

Variables
static size_t	cx
static size_t	cy
static uint8_t(*	fb )[COL_CNT][2]

Macro Definition Documentation

COL_CNT

#define COL_CNT   80

GRAY_ON_BLACK

#define GRAY_ON_BLACK   0x07

ROW_CNT

#define ROW_CNT   25

Function Documentation

clear_row()

static void clear_row ( size_t  y )

static

                     {
    size_t x;
 
    for (x = 0; x < COL_CNT; x++)
    {
        fb[y][x][0] = ' ';
        fb[y][x][1] = GRAY_ON_BLACK;
    }
}

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cls()

static void cls ( void  )

static

           {
    size_t y;
 
    for (y = 0; y < ROW_CNT; y++)
        clear_row (y);
 
    cx = cy = 0;
    move_cursor ();
}

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find_cursor()

static void find_cursor ( size_t *  x, size_t *  y  )

static

                                   {
    /* See [FREEVGA] under "Manipulating the Text-mode Cursor". */
    uint16_t cp;
 
    outb (0x3d4, 0x0e);
    cp = inb (0x3d5) << 8;
 
    outb (0x3d4, 0x0f);
    cp |= inb (0x3d5);
 
    *x = cp % COL_CNT;
    *y = cp / COL_CNT;
}

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init()

static void init ( void  )

static

            {
    /* Already initialized? */
    static bool inited;
    if (!inited) {
        fb = ptov (0xb8000);
        find_cursor (&cx, &cy);
        inited = true;
    }
}

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move_cursor()

static void move_cursor ( void  )

static

                   {
    /* See [FREEVGA] under "Manipulating the Text-mode Cursor". */
    uint16_t cp = cx + COL_CNT * cy;
    outw (0x3d4, 0x0e | (cp & 0xff00));
    outw (0x3d4, 0x0f | (cp << 8));
}

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newline()

static void newline ( void  )

static

               {
    cx = 0;
    cy++;
    if (cy >= ROW_CNT)
    {
        cy = ROW_CNT - 1;
        memmove (&fb[0], &fb[1], sizeof fb[0] * (ROW_CNT - 1));
        clear_row (ROW_CNT - 1);
    }
}

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vga_putc()

void vga_putc

(

int

c

)

                 {
    /* Disable interrupts to lock out interrupt handlers
       that might write to the console. */
    enum intr_level old_level = intr_disable ();
 
    init ();
 
    switch (c) {
        case '\n':
            newline ();
            break;
 
        case '\f':
            cls ();
            break;
 
        case '\b':
            if (cx > 0)
                cx--;
            break;
 
        case '\r':
            cx = 0;
            break;
 
        case '\t':
            cx = ROUND_UP (cx + 1, 8);
            if (cx >= COL_CNT)
                newline ();
            break;
 
        default:
            fb[cy][cx][0] = c;
            fb[cy][cx][1] = GRAY_ON_BLACK;
            if (++cx >= COL_CNT)
                newline ();
            break;
    }
 
    /* Update cursor position. */
    move_cursor ();
 
    intr_set_level (old_level);
}

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Variable Documentation

cx

size_t cx

static

cy

size_t cy

static

fb

uint8_t(* fb)[COL_CNT][2]

static