matos/drivers/vga.c

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

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

static volatile short *vga = (short *)VGA_ADDR;
static void clearScreen(uint bgColor);
static void cursorMove(int x, int y);
static void cursorEnable(uint8_t cursor_start, uint8_t cursor_end);
static void printCharDetails(char str, uint color, uint bgColor, int startX, int startY);

int VGASetup(uint bgColor, uint color)
{
    vgaBgColor = bgColor;
    vgaColor   = color;
    line       = 0;
    col        = 0;
    clearScreen(bgColor);
    cursorEnable(14, 15);
    return 0;
}

static void clearScreen(uint bgColor)
{
    uint32_t flags;
    long int colorAttr = bgColor << 12;

    disable_IRQs(flags);
    for (int i = 0; i < VGA_WIDTH * VGA_HEIGHT; i++) {
        vga[i] = colorAttr;
    }
    restore_IRQs(flags);
}

void VGAclearLine(uint bgColor, uint line)
{
    uint32_t flags;
    long int colorAttr = bgColor << 12;

    if (line >= VGA_HEIGHT)
        return;

    disable_IRQs(flags);
    for (uint i = VGA_WIDTH * line; i < VGA_WIDTH * (line + 1); i++) {
        vga[i] = colorAttr;
    }
    restore_IRQs(flags);
}

void VGAPrintf(uint color, uint bgColor, int startX, int startY, const char *format, ...)
{
    int flags;
    char tmp[VGA_WIDTH];
    int idx = 0;

    disable_IRQs(flags);

    va_list ap;
    va_start(ap, format);

    int ret = vsnprintf(tmp, sizeof(tmp), format, ap);
    while (ret > 0 && tmp[idx]) {
        printCharDetails(tmp[idx++], color, bgColor, startX++, startY);
    }
    va_end(ap);

    restore_IRQs(flags);
}

static void printCharDetails(const char str, uint color, uint bgColor, int startX, int startY)
{
    int pos = VGA_WIDTH * startY + startX;

    if (pos > VGA_WIDTH * VGA_HEIGHT || pos < 0)
        return;

    long int colorAttr = (bgColor << 4 | (color & 0x0f)) << 8;
    vga[pos]           = colorAttr | str;
}

void VGAScrollUp(void)
{
    long int colorAttr = vgaBgColor << 12;
    int flags;

    disable_IRQs(flags);
    for (int i = 1; i < VGA_HEIGHT - VGA_STATUS_LINE_HEIGHT;
         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 - 1 - VGA_STATUS_LINE_HEIGHT) * VGA_WIDTH + i] = colorAttr;
    }
    restore_IRQs(flags);
}

void VGAPutc(const char str)
{
    int flags;

    disable_IRQs(flags);
    if (str == '\n') {
        line++;
        col = 0;
        if (line >= VGA_HEIGHT - VGA_STATUS_LINE_HEIGHT) {
            VGAScrollUp();
            line--;
        }
    } else if (str == '\r') {
        col = 0;
    } else if (str == '\b') {
        col--;
        if (col < 0) {
            col = VGA_WIDTH - 1;
            line--;
            if (line < 0)
                line = 0;
        }
        printCharDetails(' ', vgaColor, vgaBgColor, col, line);
    } else {
        printCharDetails(str, vgaColor, vgaBgColor, col++, line);
        if (col == VGA_WIDTH) {
            col = 0;
            line++;
        }
        if (line >= VGA_HEIGHT - VGA_STATUS_LINE_HEIGHT) {
            VGAScrollUp();
            line--;
        }
    }

    cursorMove(col, line);
    restore_IRQs(flags);
}

static 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);
}

static void cursorMove(int x, int y)
{
    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));
}