matos/drivers/vga.c

#include "vga.h"
#include "io.h"
#include "klibc.h"

static uint vgaBgColor;
static uint vgaColor;
static int line, col;

int VGASetup(uint bgColor, uint color)
{
    vgaBgColor = bgColor;
    vgaColor   = color;
    clearScreen(bgColor);
    line = 0;
    col  = 0;
    return 0;
}

void clearScreen(uint bgColor)
{
    volatile short *vga = (short *)VGA_ADDR;
    long int colorAttr  = bgColor << 12;
    for (int i = 0; i < VGA_WIDTH * VGA_HEIGHT; i++) {
        vga[i] = colorAttr;
    }
}

void clearScreenLine(uint bgColor, uint line)
{
    volatile short *vga = (short *)VGA_ADDR;
    long int colorAttr  = bgColor << 12;
    for (uint i = VGA_WIDTH * line; i < VGA_WIDTH * (line + 1); i++) {
        vga[i] = colorAttr;
    }
}

void printIntDetails(int integer, uint color, uint bgColor, int startX, int startY)
{
    char num[sizeof(int) * 3]; // int max is 2^(sizeof(int)*8) which is (2^3)^(sizeof(int)*8/3)
                               // = 8^(sizeof(int)*8/3) ~ 10^(sizeof(int)*8/3)
    int x = startX;
    int i = 0, k = 0;
    if (integer < 0) {
        printCharDetails('-', color, bgColor, x++, startY);
    }
    if (integer == 0) {
        num[i++] = 0;
    }
    while (integer != 0) {
        int digit = integer % 10;
        num[i++]  = (digit > 0) ? digit : -digit;
        integer   = integer / 10;
    }
    for (k = i - 1; k >= 0; k--) {
        printCharDetails(num[k] + '0', color, bgColor, x++, startY);
    }
}

void printCharDetails(const char str, uint color, uint bgColor, int startX, int startY)
{
    volatile short *vga              = (short *)VGA_ADDR;
    long int colorAttr               = (bgColor << 4 | (color & 0x0f)) << 8;
    vga[VGA_WIDTH * startY + startX] = colorAttr | str;
}

void vgaScrollUp(void)
{
    long int colorAttr  = vgaBgColor << 12;
    volatile short *vga = (short *)VGA_ADDR;
    for (int i = 1; i < VGA_HEIGHT - 1; i++) { // last line is status line. Do not scroll it
        memcpy((void *)&vga[VGA_WIDTH * (i - 1)], (void *)&vga[VGA_WIDTH * i],
               VGA_WIDTH * sizeof(short));
    }
    for (int i = 0; i < VGA_WIDTH; i++) {
        vga[(VGA_HEIGHT - 2) * VGA_WIDTH + i] = colorAttr;
    }
}

void VGAputc(const char str)
{
    if (str == '\n') {
        line++;
        col = 0;
        if (line >= VGA_HEIGHT - 1) {
            vgaScrollUp();
            line--;
        }
    } else if (str == '\r') {
        col = 0;
    } else if (str == '\b') {
        col--;
        if (col < 0) {
            col = VGA_WIDTH - 1;
            line--;
        }
        printCharDetails(' ', vgaColor, vgaBgColor, col, line);
    } else {
        printCharDetails(str, vgaColor, vgaBgColor, col++, line);
        if (col == VGA_WIDTH) {
            col = 0;
            line++;
        }
        if (line >= VGA_HEIGHT - 1) {
            vgaScrollUp();
            line--;
        }
    }
    cursorMove(col, line);
}

void printStringDetails(const char *str, uint color, uint bgColor, int startX, int startY)
{
    volatile short *vga = (short *)VGA_ADDR;
    int i               = 0;
    long int colorAttr  = (bgColor << 4 | (color & 0x0f)) << 8;
    while (*str) {
        vga[VGA_WIDTH * startY + startX + i] = colorAttr | *str;
        str++;
        i++;
    }
}

void cursorEnable(uint8_t cursor_start, uint8_t cursor_end)
{
    outb(0x3D4, 0x0A);
    outb(0x3D5, (inb(0x3D5) & 0xC0) | cursor_start);

    outb(0x3D4, 0x0B);
    outb(0x3D5, (inb(0x3D5) & 0xE0) | cursor_end);
}

void cursorDisable(void)
{
    outb(0x3D4, 0x0A);
    outb(0x3D5, 0x20);
}

void cursorMove(int x, int y)
{
    volatile short *vga = (short *)VGA_ADDR;
    long int colorAttr  = (vgaBgColor << 4 | (vgaColor & 0x0f)) << 8;
    uint16_t pos        = y * VGA_WIDTH + x;
    vga[pos]            = colorAttr;

    outb(0x3D4, 0x0F);
    outb(0x3D5, (uint8_t)(pos & 0xFF));
    outb(0x3D4, 0x0E);
    outb(0x3D5, (uint8_t)((pos >> 8) & 0xFF));
}