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revise bit packing funcs in vips2tiff

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smaller, simpler
This commit is contained in:
John Cupitt 2020-06-17 14:28:13 +01:00
parent 19077b53ac
commit 3b07f72b67
1 changed files with 16 additions and 86 deletions
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102
libvips/foreign/vips2tiff.c
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@ -1285,91 +1285,33 @@ LabQ2LabC( VipsPel *q, VipsPel *p, int n )
}
}
/* Pack 8 bit VIPS to 1 bit TIFF.
/* Pack 8 bit VIPS to N bit TIFF.
*/
static void
eightbit2onebit( Wtiff *wtiff, VipsPel *q, VipsPel *p, int n )
eightbit2nbit( Wtiff *wtiff, VipsPel *q, VipsPel *p, int n )
{
/* Invert in miniswhite mode.
*/
int white = wtiff->miniswhite ? 0 : 1;
int black = white ^ 1;
VipsPel mask = wtiff->miniswhite ? 255 : 0;
int pixel_mask = 8 / wtiff->bitdepth - 1;
int shift = 8 - wtiff->bitdepth;
int x;
VipsPel bits;
int x;
bits = 0;
for( x = 0; x < n; x++ ) {
bits <<= 1;
if( p[x] >= 128 )
bits |= white;
else
bits |= black;
bits <<= wtiff->bitdepth;
bits |= p[x] >> shift;
if( (x & 0x7) == 0x7 ) {
*q++ = bits;
bits = 0;
}
if( (x & pixel_mask) == pixel_mask )
*q++ = bits ^ mask;
}
/* Any left-over bits? Need to be left-aligned.
*/
if( (x & 0x7) != 0 )
*q++ = bits << (8 - (x & 0x7));
}
/* Pack 8 bit VIPS to 2 bit TIFF.
*/
static void
eightbit2twobit( Wtiff *wtiff, VipsPel *q, VipsPel *p, int n )
{
VipsPel mask = wtiff->miniswhite ? 3 : 0;
int x;
VipsPel bits;
bits = 0;
for( x = 0; x < n; x++ ) {
bits <<= 2;
bits |= (p[x] >> 6) ^ mask;
if( (x & 0x3) == 0x3 ) {
*q++ = bits;
bits = 0;
}
}
/* Any left-over bits? Need to be left-aligned.
*/
if( (x & 0x3) != 0 )
*q++ = bits << (8 - ((x & 0x3) << 1));
}
/* Pack 8 bit VIPS to 4 bit TIFF.
*/
static void
eightbit2fourbit( Wtiff *wtiff, VipsPel *q, VipsPel *p, int n )
{
VipsPel mask = wtiff->miniswhite ? 0xf : 0;
VipsPel bits;
int x;
bits = 0;
for( x = 0; x < n; x++ ) {
bits <<= 4;
bits |= (p[x] >> 4) ^ mask;
if( (x & 0x1) == 0x1 ) {
*q++ = bits;
bits = 0;
}
}
/* Any left-over bits? Need to be left-aligned.
*/
if( (x & 0x1) != 0 )
*q++ = bits << (8 - ((x & 0x1) << 2));
if( (x & pixel_mask) != 0 )
*q++ = (bits ^ mask) << (8 - (x & pixel_mask));
}
/* Swap the sense of the first channel, if necessary.
@ -1516,12 +1458,8 @@ wtiff_pack2tiff( Wtiff *wtiff, Layer *layer,
if( wtiff->ready->Coding == VIPS_CODING_LABQ )
LabQ2LabC( q, p, area->width );
else if( wtiff->bitdepth == 1 )
eightbit2onebit( wtiff, q, p, area->width );
else if( wtiff->bitdepth == 2 )
eightbit2twobit( wtiff, q, p, area->width );
else if( wtiff->bitdepth == 4 )
eightbit2fourbit( wtiff, q, p, area->width );
else if( wtiff->bitdepth > 0 )
eightbit2nbit( wtiff, q, p, area->width );
else if( wtiff->input->Type == VIPS_INTERPRETATION_XYZ )
XYZ2tiffxyz( q, p, area->width, in->im->Bands );
else if( (in->im->Bands == 1 || in->im->Bands == 2) &&
@ -1619,16 +1557,8 @@ wtiff_layer_write_strip( Wtiff *wtiff, Layer *layer, VipsRegion *strip )
XYZ2tiffxyz( wtiff->tbuf, p, im->Xsize, im->Bands );
p = wtiff->tbuf;
}
else if( wtiff->bitdepth == 1 ) {
eightbit2onebit( wtiff, wtiff->tbuf, p, im->Xsize );
p = wtiff->tbuf;
}
else if( wtiff->bitdepth == 2 ) {
eightbit2twobit( wtiff, wtiff->tbuf, p, im->Xsize );
p = wtiff->tbuf;
}
else if( wtiff->bitdepth == 4 ) {
eightbit2fourbit( wtiff, wtiff->tbuf, p, im->Xsize );
else if( wtiff->bitdepth > 0 ) {
eightbit2nbit( wtiff, wtiff->tbuf, p, im->Xsize );
p = wtiff->tbuf;
}
else if( (im->Bands == 1 || im->Bands == 2) &&