Problem with PIXEL_FROM_RGBA on 16 bit screens and Big endian systems

SDL Development
1

Hi,

On Big endian systems CPU register hold the color bits as this.to convert
the data with that macro Gloss must set to 5.
But the produce C code does not rotate so the lower bits are truncate and
green color have only 8 steps then and sdl on 16 bit look so ugly then.

gggbbbbbrrrrrggg

#define PIXEL_FROM_RGBA(Pixel, fmt, r, g, b, a) \
{ \
Pixel = ((r>>fmt->Rloss)<Rshift)| \
((g>>fmt->Gloss)<Gshift)| \
((b>>fmt->Bloss)<Bshift)| \
((a>>fmt->Aloss)<Ashift); \
\
}

I see there is for little endian a table.when i set all mask bits to 0 (SDL
used the default then ), speed is higher.seem code dont use the
PIXEL_FROM_RGBA macro then

Maybe somebody know how this table can modify, so big endian systems work
faster ?.Is it ok, when the table is byteswap ?.

is in sdl_blit_n (1.2.13 i use)

  • Special optimized blit for RGB 5-6-5 --> ARGB 8-8-8-8 */
    static const Uint32 RGB565_ARGB8888_LUT[512] = {
    0x00000000, 0xff000000, 0x00000008, 0xff002000,
    0x00000010, 0xff004000, 0x00000018, 0xff006100,
    0x00000020, 0xff008100, 0x00000029, 0xff00a100,

I have done for test a faster macro for big endian, but it is still slower
tan little endian.the sdl_swap16 is only a asm instruction and the macro
is because of no alpha and 1 shift fewer faster execute and speedup big
endian a little and show full colors.

if (fmt->Gloss == 5)
{
Pixel = SDL_Swap16(((g>>2)<<5)|
((r>>3)<<11)|
(b>>3)); \
*((Uint16 *)(buf)) = Pixel;
}
else
PIXEL_FROM_RGBA(Pixel, fmt, r, g, b, a);
*((Uint16 *)(buf)) = (Pixel);
}

Bye