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ps_image.cxx: better byte-swapping algorithm.

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git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@7506 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
This commit is contained in:
Manolo Gouy 2010-04-15 08:24:25 +00:00
parent fe76949b83
commit 595b20f802
1 changed files with 6 additions and 15 deletions
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21
src/ps_image.cxx
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@ -182,22 +182,13 @@ int Fl_PSfile_Device::alpha_mask(const uchar * data, int w, int h, int D, int LD
return 0;
}
// bitwise inversion of all 4-bit quantities
static const unsigned char swapped[16] = {0,8,4,12,2,10,6,14,1,9,5,13,3,11,7,15};
// TODO: anybody has more efficient algoritm?
static inline uchar swap_byte(const uchar i){
uchar b =0;
if(i & 1) b |= 128;
if(i & 2) b |= 64;
if(i & 4) b |= 32;
if(i & 8) b |= 16;
if(i & 16) b |= 8;
if(i & 32) b |= 4;
if(i & 64) b |= 2;
if(i & 128) b |= 1;
return b;
}
// bitwise inversion of a byte
static inline uchar swap_byte(const uchar b){
return (swapped[b & 0xF] << 4) | swapped[b >> 4];
}
extern uchar **fl_mask_bitmap;