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Fix issues with RGB565 color conversion on big endian machines. The RGB565 routines are now abstracted in a separate file, with separate little-endian and big-endian versions defined at compile time through the use of macros (this is similar to how the colorspace extension routines work.) This allows big-endian machines to take advantage of the same performance optimizations as little-endian machines, and it retains the performance on little-endian machines, since the conditional branch for endianness is at a very coarse-grained level.

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git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.4.x@1399 632fc199-4ca6-4c93-a231-07263d6284db
This commit is contained in:
DRC
2014-08-30 20:37:50 +00:00
parent eb8d096ba6
commit 72a3cc0ecd
6 changed files with 680 additions and 402 deletions
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30
wrbmp.c
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@@ -5,6 +5,7 @@
* Copyright (C) 1994-1996, Thomas G. Lane.
* libjpeg-turbo Modifications:
* Copyright (C) 2013, Linaro Limited.
* Copyright (C) 2014, D. R. Commander.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains routines to write output images in Microsoft "BMP"
@@ -64,6 +65,15 @@ LOCAL(void) write_colormap
int map_entry_size);
static inline boolean is_big_endian(void)
{
int test_value = 1;
if(*(char *)&test_value != 1)
return TRUE;
return FALSE;
}
/*
* Write some pixel data.
* In this module rows_supplied will always be 1.
@@ -93,18 +103,18 @@ put_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
outptr = image_ptr[0];
if(cinfo->out_color_space == JCS_RGB565) {
#define red_mask 0xF800
#define green_mask 0x7E0
#define blue_mask 0x1F
unsigned char r, g, b;
boolean big_endian = is_big_endian();
unsigned short *inptr2 = (unsigned short *)inptr;
for (col = cinfo->output_width; col > 0; col--) {
r = (*inptr2 & red_mask) >> 11;
g = (*inptr2 & green_mask) >> 5;
b = (*inptr2 & blue_mask);
outptr[0] = b << 3;
outptr[1] = g << 2;
outptr[2] = r << 3;
if (big_endian) {
outptr[0] = (*inptr2 >> 5) & 0xF8;
outptr[1] = ((*inptr2 << 5) & 0xE0) | ((*inptr2 >> 11) & 0x1C);
outptr[2] = *inptr2 & 0xF8;
} else {
outptr[0] = (*inptr2 << 3) & 0xF8;
outptr[1] = (*inptr2 >> 3) & 0xFC;
outptr[2] = (*inptr2 >> 8) & 0xF8;
}
outptr += 3;
inptr2++;
}