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gdk: optimize native RGB555 conversion

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Use an aligned four-pixel integer converter for native little-endian RGB555 images. Keep the scalar implementation for narrow, unaligned and big-endian paths.
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Daemonratte 2026-08-14 08:57:01 +02:00
commit 7dd6c04cb8
1 changed files with 68 additions and 0 deletions
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68
gdk/gdkrgb.c
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@ -2011,6 +2011,74 @@ gdk_rgb_convert_555 (GdkRgbInfo *image_info, GdkImage *image,
bptr = buf;
bpl = image->bpl;
obuf = ((guchar *)image->mem) + y0 * bpl + x0 * 2;
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
/* GTK2_NG_WIDE_555 */
if (width >= 32 &&
((((guintptr) obuf |
(guintptr) bptr |
(guintptr) rowstride |
(guintptr) bpl) & 3) == 0))
{
for (y = 0; y < height; y++)
{
guchar *obptr;
bp2 = bptr;
obptr = obuf;
for (x = 0; x < width - 3; x += 4)
{
guint32 w0;
guint32 w1;
guint32 w2;
w0 = ((const guint32 *) bp2)[0];
w1 = ((const guint32 *) bp2)[1];
w2 = ((const guint32 *) bp2)[2];
((guint32 *) obptr)[0] =
((w0 & 0x000000f8U) << 7) |
((w0 & 0x0000f800U) >> 6) |
((w0 & 0x00f80000U) >> 19) |
((w0 & 0xf8000000U) >> 1) |
((w1 & 0x000000f8U) << 18) |
((w1 & 0x0000f800U) << 5);
((guint32 *) obptr)[1] =
((w1 & 0x00f80000U) >> 9) |
((w1 & 0xf8000000U) >> 22) |
((w2 & 0x000000f8U) >> 3) |
((w2 & 0x0000f800U) << 15) |
((w2 & 0x00f80000U) << 2) |
((w2 & 0xf8000000U) >> 11);
bp2 += 12;
obptr += 8;
}
for (; x < width; x++)
{
r = *bp2++;
g = *bp2++;
b = *bp2++;
((guint16 *) obptr)[0] =
((r & 0xf8) << 7) |
((g & 0xf8) << 2) |
(b >> 3);
obptr += 2;
}
bptr += rowstride;
obuf += bpl;
}
return;
}
#endif
for (y = 0; y < height; y++)
{
bp2 = bptr;