Luna/kernel/src/render/TextRenderer.cpp

#include "render/TextRenderer.h"
#include "bootboot.h"
#include "init/InitRD.h"
#include "io/Serial.h"
#include "psf2.h"
#include "render/Framebuffer.h"
#include "std/stdio.h"
#include "std/string.h"

extern BOOTBOOT bootboot;

static psf2_t* font;
static Color bgColor = Color::Black;
static Color fgColor = Color::White;
static uint32_t xpos = 0;
static uint32_t ypos = 0;

bool TextRenderer::try_initialize()
{
    InitRD::File font_file = InitRD::find_file("boot/font.psf");
    if (!font_file.addr)
    {
        Serial::println("Failed to load boot/font.psf from initrd");
        return false;
    }
    font = (psf2_t*)font_file.addr;
    if (font->magic != PSF_FONT_MAGIC)
    {
        Serial::println("Font magic does not match PSF font magic");
        return false;
    }
    return true;
}

bool TextRenderer::is_initialized()
{
    return font; // if font is NULL, not initialized, else yes
}

static void putchar_at_offset(char c, int cx, int cy, Color& fg, Color& bg)
{
    uint8_t* glyph =
        (uint8_t*)font + font->headersize + (c > 0 && (uint32_t)c < font->numglyph ? c : 0) * font->bytesperglyph;
    int mask;
    for (uint32_t y = 0; y < font->height; y++)
    {
        mask = 1 << (font->width - 1);
        for (uint32_t x = 0; x < font->width; x++)
        {
            framebuffer0.set_pixel(cx + x, cy + y, *((uint32_t*)glyph) & mask ? fg : bg);
            mask >>= 1;
        }
    }
}

void TextRenderer::putchar(char chr)
{
    switch (chr)
    {
    case '\n':
        ypos += font->height;
        if ((ypos + font->height) >= bootboot.fb_height)
        {
            memcpy((void*)bootboot.fb_ptr, (uint32_t*)bootboot.fb_ptr + (bootboot.fb_scanline * font->height),
                   bootboot.fb_size - (sizeof(uint32_t) * bootboot.fb_scanline * font->height));
            ypos -= font->height;
            framebuffer0.paint_rect(0, ypos, bootboot.fb_width, font->height, Color::Black);
        }
        xpos = 0;
        break;
    case '\r': xpos = 0; break;
    case '\b':
        if (xpos != 0)
        {
            xpos -= font->width + 1;
            framebuffer0.paint_rect(xpos, ypos, font->width + 1, font->height, Color::Black);
        }
        break;
    default:
        putchar_at_offset(chr, xpos, ypos, fgColor, bgColor);
        xpos += font->width + 1;
        if ((xpos + font->width + 1) > bootboot.fb_width)
        {
            xpos = 0;
            ypos += font->height;
            if (ypos > bootboot.fb_height)
            {
                memcpy((void*)bootboot.fb_ptr, (uint32_t*)bootboot.fb_ptr + (bootboot.fb_scanline * font->height),
                       bootboot.fb_size - (sizeof(uint32_t) * bootboot.fb_scanline * font->height));
                ypos -= font->height;
                framebuffer0.paint_rect(0, ypos, bootboot.fb_width, font->height, Color::Black);
            }
        }
        break;
    }
}

void TextRenderer::write(const char* str, size_t size)
{
    for (size_t i = 0; i < size; i++) { putchar(str[i]); }
}