vga.cx

//-*-C-*-
/*******************************************************************************
*   ___   public
*  ¦OUX¦  C+
*  ¦/C+¦  OUX/C+ OS
*   ---   kernel
*         VGA driver
* ©overcq                on ‟Gentoo Linux 17.1” “x86_64”             2021‒5‒16 K
*******************************************************************************/
enum E_vga_Z_aa_pixel
{ E_vga_Z_aa_pixel_S_e = 1 << 0,
  E_vga_Z_aa_pixel_S_se = 1 << 1,
  E_vga_Z_aa_pixel_S_s = 1 << 2,
  E_vga_Z_aa_pixel_S_sw = 1 << 3,
  E_vga_Z_aa_pixel_S_w = 1 << 4,
  E_vga_Z_aa_pixel_S_nw = 1 << 5,
  E_vga_Z_aa_pixel_S_n = 1 << 6,
  E_vga_Z_aa_pixel_S_ne = 1 << 7
};
//==============================================================================
_private N32 *E_vga_S_framebuffer;
//==============================================================================
_private
N32
E_vga_Z_color_M(
  N8 red
, N8 green
, N8 blue
){  return ( (N32)blue << E_main_S_framebuffer.pixel_shifts.blue )
    | ( (N32)green << E_main_S_framebuffer.pixel_shifts.green )
    | ( (N32)red << E_main_S_framebuffer.pixel_shifts.red );
}
_private
N8
E_vga_Z_color_R_red( N32 color
){  return ( color >> E_main_S_framebuffer.pixel_shifts.red ) & 0xff;
}
_private
N8
E_vga_Z_color_R_green( N32 color
){  return ( color >> E_main_S_framebuffer.pixel_shifts.green ) & 0xff;
}
_private
N8
E_vga_Z_color_R_blue( N32 color
){  return ( color >> E_main_S_framebuffer.pixel_shifts.blue ) & 0xff;
}
_private
N32
E_vga_Z_color_M_gray( N8 luminance
){  return E_vga_Z_color_M( luminance, luminance, luminance );
}
_private
N32
E_vga_R_video_color( N32 color
){  return ((( color >> 16 ) & 0xff ) << E_main_S_framebuffer.pixel_shifts.blue )
    | ((( color >> 8 ) & 0xff ) << E_main_S_framebuffer.pixel_shifts.green )
    | (( color & 0xff ) << E_main_S_framebuffer.pixel_shifts.red );
}
_private
N32
E_vga_R_color( N32 video_color
){  return ((( video_color >> E_main_S_framebuffer.pixel_shifts.blue ) & 0xff ) << 16 )
    | ((( video_color >> E_main_S_framebuffer.pixel_shifts.green ) & 0xff ) << 8 )
    | (( video_color >> E_main_S_framebuffer.pixel_shifts.red ) & 0xff );
}
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
_private
N32
E_vga_R_pixel(
  N32 x
, N32 y
){  return *( E_main_S_framebuffer.p + y * E_main_S_framebuffer.pixels_per_scan_line + x );
}
_private
void
E_vga_P_pixel(
  N32 x
, N32 y
, N32 video_color
){  *( E_vga_S_framebuffer + y * E_main_S_framebuffer.width + x ) = video_color;
}
_private
void
E_vga_I_set_pixel_aa(
  N32 x
, N32 y
, N32 color
, F brightness
, N8 get_pixel
){  N background_red, background_green, background_blue;
    N n = 0;
    N p[8];
    p[0] = ( get_pixel & E_vga_Z_aa_pixel_S_e ) && x + 1 != E_main_S_framebuffer.width ? E_vga_R_color( E_vga_R_pixel( x + 1, y )) : color;
    p[1] = ( get_pixel & E_vga_Z_aa_pixel_S_se ) && x + 1 != E_main_S_framebuffer.width && y + 1 != E_main_S_framebuffer.height ? E_vga_R_color( E_vga_R_pixel( x + 1, y + 1 )) : color;
    p[2] = ( get_pixel & E_vga_Z_aa_pixel_S_s ) && y + 1 != E_main_S_framebuffer.height ? E_vga_R_color( E_vga_R_pixel( x, y + 1 )) : color;
    p[3] = ( get_pixel & E_vga_Z_aa_pixel_S_sw ) && x && y + 1 != E_main_S_framebuffer.height ? E_vga_R_color( E_vga_R_pixel( x - 1, y + 1 )) : color;
    p[4] = ( get_pixel & E_vga_Z_aa_pixel_S_w ) && x ? E_vga_R_color( E_vga_R_pixel( x - 1, y )) : color;
    p[5] = ( get_pixel & E_vga_Z_aa_pixel_S_nw ) && x && y ? E_vga_R_color( E_vga_R_pixel( x - 1, y - 1 )) : color;
    p[6] = ( get_pixel & E_vga_Z_aa_pixel_S_n ) && y ? E_vga_R_color( E_vga_R_pixel( x, y - 1 )) : color;
    p[7] = ( get_pixel & E_vga_Z_aa_pixel_S_ne ) && x + 1 != E_main_S_framebuffer.width && y ? E_vga_R_color( E_vga_R_pixel( x + 1, y - 1 )) : color;
    background_red = background_green = background_blue = 0;
    for_n( i, 8 )
        if( p[i] != color )
        {   background_red += E_vga_Z_color_R_red( p[i] );
            background_green += E_vga_Z_color_R_green( p[i] );
            background_blue += E_vga_Z_color_R_red( p[i] );
            n++;
        }
    if(n)
    {   background_red /= n;
        background_green /= n;
        background_blue /= n;
    }else
    {   background_red = E_vga_Z_color_R_red( E_vga_S_background_color );
        background_green = E_vga_Z_color_R_green( E_vga_S_background_color );
        background_blue = E_vga_Z_color_R_blue( E_vga_S_background_color );
    }
    N8 red = E_vga_Z_color_R_red(color);
    N8 green = E_vga_Z_color_R_green(color);
    N8 blue = E_vga_Z_color_R_blue(color);
    if( red > background_red )
        red = background_red + ( red - background_red ) * brightness;
    else
        red = background_red - ( background_red - red ) * brightness;
    if( green > background_green )
        green = background_green + ( green - background_green ) * brightness;
    else
        green = background_green - ( background_green - green ) * brightness;
    if( blue > background_blue )
        blue = background_blue + ( blue - background_blue ) * brightness;
    else
        blue = background_blue - ( background_blue - blue ) * brightness;
    E_vga_P_pixel( x, y, E_vga_R_video_color( E_vga_Z_color_M( red, green, blue )));
}
_private
void
E_vga_I_draw_x_line(
  N32 x
, N32 y
, N32 width
, N32 video_color
){  for_n( x_i, width )
    {   if( x + x_i == E_main_S_framebuffer.width )
            break;
        *( E_vga_S_framebuffer + y * E_main_S_framebuffer.width + x + x_i ) = video_color;
    }
}
_private
void
E_vga_I_draw_y_line(
  N32 x
, N32 y
, N32 height
, N32 video_color
){  for_n( y_i, height )
    {   if( y + y_i == E_main_S_framebuffer.height )
            break;
        *( E_vga_S_framebuffer + ( y + y_i ) * E_main_S_framebuffer.width + x ) = video_color;
    }
}
_private
void
E_vga_I_draw_line(
  N32 x_0
, N32 y_0
, N32 x_1
, N32 y_1
, N32 video_color
){  if( x_0 == x_1 )
        E_vga_I_draw_y_line( x_0, y_0, y_1 - y_0 + 1, video_color );
    else if( y_0 == y_1 )
        E_vga_I_draw_x_line( x_0, y_0, x_1 - x_0 + 1, video_color );
    else
    {   S32 dx_ = x_1 - x_0, dx = J_abs( dx_ );
        S32 dy_ = y_1 - y_0, dy = J_abs( dy_ );
        S32 x = x_0, x_end = x_1, y = y_0, y_end = y_1;
        S32 di = 1;
        if( dy > dx )
        {   if( dy_ < 0 )
            {   J_swap( S32, y, y_end );
                J_swap( S32, x, x_end );
            }
            E_vga_P_pixel( x, y, video_color );
            if( x > x_end )
                di = -di;
            S32 d = dx - dy / 2;
            while( y != y_end )
            {   y++;
                if( d < 0 )
                    d += dx;
                else
                {   d += dx - dy;
                    x += di;
                }
                E_vga_P_pixel( x, y, video_color );
            }
        }else
        {   if( dx_ < 0 )
            {   J_swap( S32, x, x_end );
                J_swap( S32, y, y_end )
            }
            E_vga_P_pixel( x, y, video_color );
            if( y > y_end )
                di = -di;
            S32 d = dy - dx / 2;
            while( x != x_end )
            {   x++;
                if( d < 0 )
                    d += dy;
                else
                {   d += dy - dx;
                    y += di;
                }
                E_vga_P_pixel( x, y, video_color );
            }
        }
    }
}
_private
void
E_vga_I_draw_rect(
  N32 x
, N32 y
, N32 width
, N32 height
, N8 thickness
, N32 video_color
){  for_n( x_i, width )
    {   for_n( i, thickness )
            *( E_vga_S_framebuffer + ( y + i ) * E_main_S_framebuffer.width + x + x_i ) = video_color;
    }
    for_n( y_i, height - 2 * thickness )
    {   for_n( i, thickness )
        {   *( E_vga_S_framebuffer + ( y + thickness + y_i ) * E_main_S_framebuffer.width + x + i ) = video_color;
            *( E_vga_S_framebuffer + ( y + thickness + y_i ) * E_main_S_framebuffer.width + x + width - 1 - i ) = video_color;
        }
    }
    for_n_( x_i, width )
    {   for_n_rev( i, thickness )
            *( E_vga_S_framebuffer + ( y + height - 1 - i ) * E_main_S_framebuffer.width + x + x_i ) = video_color;
    }
}
_private
void
E_vga_I_fill_rect(
  N32 x
, N32 y
, N32 width
, N32 height
, N32 video_color
){  for_n( y_i, height )
    {   for_n( x_i, width )
            *( E_vga_S_framebuffer + ( y + y_i ) * E_main_S_framebuffer.width + x + x_i ) = video_color;
    }
}
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
_private
void
E_vga_Q_buffer_I_draw( N32 x
, N32 y
, N32 width
, N32 height
){  volatile N32 *video_address = E_main_S_framebuffer.p + y * E_main_S_framebuffer.pixels_per_scan_line + x;
    for_n( y_i, height )
    {   for_n( x_i, width )
            video_address[ x_i ] = *( E_vga_S_framebuffer + ( y + y_i ) * E_main_S_framebuffer.width + x + x_i );
        video_address += E_main_S_framebuffer.pixels_per_scan_line;
    }
}
/******************************************************************************/