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351d5d08fa04404bb6a4c65e5535a942ff407806
mozjpeg/jdsample.c
DRC 19c791cdac Improve code formatting consistency 
With rare exceptions ...
- Always separate line continuation characters by one space from
  preceding code.
- Always use two-space indentation.  Never use tabs.
- Always use K&R-style conditional blocks.
- Always surround operators with spaces, except in raw assembly code.
- Always put a space after, but not before, a comma.
- Never put a space between type casts and variables/function calls.
- Never put a space between the function name and the argument list in
  function declarations and prototypes.
- Always surround braces ('{' and '}') with spaces.
- Always surround statements (if, for, else, catch, while, do, switch)
  with spaces.
- Always attach pointer symbols ('*' and '**') to the variable or
  function name.
- Always precede pointer symbols ('*' and '**') by a space in type
  casts.
- Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG
  API libraries (using min() from tjutil.h is still necessary for
  TJBench.)
- Where it makes sense (particularly in the TurboJPEG code), put a blank
  line after variable declaration blocks.
- Always separate statements in one-liners by two spaces.

The purpose of this was to ease maintenance on my part and also to make
it easier for contributors to figure out how to format patch
submissions.  This was admittedly confusing (even to me sometimes) when
we had 3 or 4 different style conventions in the same source tree.  The
new convention is more consistent with the formatting of other OSS code
bases.

This commit corrects deviations from the chosen formatting style in the
libjpeg API code and reformats the TurboJPEG API code such that it
conforms to the same standard.

NOTES:
- Although it is no longer necessary for the function name in function
  declarations to begin in Column 1 (this was historically necessary
  because of the ansi2knr utility, which allowed libjpeg to be built
  with non-ANSI compilers), we retain that formatting for the libjpeg
  code because it improves readability when using libjpeg's function
  attribute macros (GLOBAL(), etc.)
- This reformatting project was accomplished with the help of AStyle and
  Uncrustify, although neither was completely up to the task, and thus
  a great deal of manual tweaking was required.  Note to developers of
  code formatting utilities:  the libjpeg-turbo code base is an
  excellent test bed, because AFAICT, it breaks every single one of the
  utilities that are currently available.
- The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been
  formatted to match the SSE2 code (refer to
  ff5685d5344273df321eb63a005eaae19d2496e3.)  I hadn't intended to
  bother with this, but the Loongson MMI implementation demonstrated
  that there is still academic value to the MMX implementation, as an
  algorithmic model for other 64-bit vector implementations.  Thus, it
  is desirable to improve its readability in the same manner as that of
  the SSE2 implementation.
2018-03-16 02:14:34 -05:00

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/*
* jdsample.c
*
* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1991-1996, Thomas G. Lane.
* libjpeg-turbo Modifications:
* Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
* Copyright (C) 2010, 2015-2016, D. R. Commander.
* Copyright (C) 2014, MIPS Technologies, Inc., California.
* Copyright (C) 2015, Google, Inc.
* For conditions of distribution and use, see the accompanying README.ijg
* file.
*
* This file contains upsampling routines.
*
* Upsampling input data is counted in "row groups". A row group
* is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
* sample rows of each component. Upsampling will normally produce
* max_v_samp_factor pixel rows from each row group (but this could vary
* if the upsampler is applying a scale factor of its own).
*
* An excellent reference for image resampling is
* Digital Image Warping, George Wolberg, 1990.
* Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
*/
#include "jinclude.h"
#include "jdsample.h"
#include "jsimd.h"
#include "jpegcomp.h"
/*
* Initialize for an upsampling pass.
*/
METHODDEF(void)
start_pass_upsample(j_decompress_ptr cinfo)
{
my_upsample_ptr upsample = (my_upsample_ptr)cinfo->upsample;
/* Mark the conversion buffer empty */
upsample->next_row_out = cinfo->max_v_samp_factor;
/* Initialize total-height counter for detecting bottom of image */
upsample->rows_to_go = cinfo->output_height;
}
/*
* Control routine to do upsampling (and color conversion).
*
* In this version we upsample each component independently.
* We upsample one row group into the conversion buffer, then apply
* color conversion a row at a time.
*/
METHODDEF(void)
sep_upsample(j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail,
JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
JDIMENSION out_rows_avail)
{
my_upsample_ptr upsample = (my_upsample_ptr)cinfo->upsample;
int ci;
jpeg_component_info *compptr;
JDIMENSION num_rows;
/* Fill the conversion buffer, if it's empty */
if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
/* Invoke per-component upsample method. Notice we pass a POINTER
* to color_buf[ci], so that fullsize_upsample can change it.
*/
(*upsample->methods[ci]) (cinfo, compptr,
input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
upsample->color_buf + ci);
}
upsample->next_row_out = 0;
}
/* Color-convert and emit rows */
/* How many we have in the buffer: */
num_rows = (JDIMENSION)(cinfo->max_v_samp_factor - upsample->next_row_out);
/* Not more than the distance to the end of the image. Need this test
* in case the image height is not a multiple of max_v_samp_factor:
*/
if (num_rows > upsample->rows_to_go)
num_rows = upsample->rows_to_go;
/* And not more than what the client can accept: */
out_rows_avail -= *out_row_ctr;
if (num_rows > out_rows_avail)
num_rows = out_rows_avail;
(*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
(JDIMENSION)upsample->next_row_out,
output_buf + *out_row_ctr, (int)num_rows);
/* Adjust counts */
*out_row_ctr += num_rows;
upsample->rows_to_go -= num_rows;
upsample->next_row_out += num_rows;
/* When the buffer is emptied, declare this input row group consumed */
if (upsample->next_row_out >= cinfo->max_v_samp_factor)
(*in_row_group_ctr)++;
}
/*
* These are the routines invoked by sep_upsample to upsample pixel values
* of a single component. One row group is processed per call.
*/
/*
* For full-size components, we just make color_buf[ci] point at the
* input buffer, and thus avoid copying any data. Note that this is
* safe only because sep_upsample doesn't declare the input row group
* "consumed" until we are done color converting and emitting it.
*/
METHODDEF(void)
fullsize_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr,
JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
*output_data_ptr = input_data;
}
/*
* This is a no-op version used for "uninteresting" components.
* These components will not be referenced by color conversion.
*/
METHODDEF(void)
noop_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr,
JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
*output_data_ptr = NULL; /* safety check */
}
/*
* This version handles any integral sampling ratios.
* This is not used for typical JPEG files, so it need not be fast.
* Nor, for that matter, is it particularly accurate: the algorithm is
* simple replication of the input pixel onto the corresponding output
* pixels. The hi-falutin sampling literature refers to this as a
* "box filter". A box filter tends to introduce visible artifacts,
* so if you are actually going to use 3:1 or 4:1 sampling ratios
* you would be well advised to improve this code.
*/
METHODDEF(void)
int_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr,
JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
my_upsample_ptr upsample = (my_upsample_ptr)cinfo->upsample;
JSAMPARRAY output_data = *output_data_ptr;
register JSAMPROW inptr, outptr;
register JSAMPLE invalue;
register int h;
JSAMPROW outend;
int h_expand, v_expand;
int inrow, outrow;
h_expand = upsample->h_expand[compptr->component_index];
v_expand = upsample->v_expand[compptr->component_index];
inrow = outrow = 0;
while (outrow < cinfo->max_v_samp_factor) {
/* Generate one output row with proper horizontal expansion */
inptr = input_data[inrow];
outptr = output_data[outrow];
outend = outptr + cinfo->output_width;
while (outptr < outend) {
invalue = *inptr++; /* don't need GETJSAMPLE() here */
for (h = h_expand; h > 0; h--) {
*outptr++ = invalue;
}
}
/* Generate any additional output rows by duplicating the first one */
if (v_expand > 1) {
jcopy_sample_rows(output_data, outrow, output_data, outrow + 1,
v_expand - 1, cinfo->output_width);
}
inrow++;
outrow += v_expand;
}
}
/*
* Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
* It's still a box filter.
*/
METHODDEF(void)
h2v1_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr,
JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
JSAMPARRAY output_data = *output_data_ptr;
register JSAMPROW inptr, outptr;
register JSAMPLE invalue;
JSAMPROW outend;
int inrow;
for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
inptr = input_data[inrow];
outptr = output_data[inrow];
outend = outptr + cinfo->output_width;
while (outptr < outend) {
invalue = *inptr++; /* don't need GETJSAMPLE() here */
*outptr++ = invalue;
*outptr++ = invalue;
}
}
}
/*
* Fast processing for the common case of 2:1 horizontal and 2:1 vertical.
* It's still a box filter.
*/
METHODDEF(void)
h2v2_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr,
JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
JSAMPARRAY output_data = *output_data_ptr;
register JSAMPROW inptr, outptr;
register JSAMPLE invalue;
JSAMPROW outend;
int inrow, outrow;
inrow = outrow = 0;
while (outrow < cinfo->max_v_samp_factor) {
inptr = input_data[inrow];
outptr = output_data[outrow];
outend = outptr + cinfo->output_width;
while (outptr < outend) {
invalue = *inptr++; /* don't need GETJSAMPLE() here */
*outptr++ = invalue;
*outptr++ = invalue;
}
jcopy_sample_rows(output_data, outrow, output_data, outrow + 1, 1,
cinfo->output_width);
inrow++;
outrow += 2;
}
}
/*
* Fancy processing for the common case of 2:1 horizontal and 1:1 vertical.
*
* The upsampling algorithm is linear interpolation between pixel centers,
* also known as a "triangle filter". This is a good compromise between
* speed and visual quality. The centers of the output pixels are 1/4 and 3/4
* of the way between input pixel centers.
*
* A note about the "bias" calculations: when rounding fractional values to
* integer, we do not want to always round 0.5 up to the next integer.
* If we did that, we'd introduce a noticeable bias towards larger values.
* Instead, this code is arranged so that 0.5 will be rounded up or down at
* alternate pixel locations (a simple ordered dither pattern).
*/
METHODDEF(void)
h2v1_fancy_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr,
JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
JSAMPARRAY output_data = *output_data_ptr;
register JSAMPROW inptr, outptr;
register int invalue;
register JDIMENSION colctr;
int inrow;
for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
inptr = input_data[inrow];
outptr = output_data[inrow];
/* Special case for first column */
invalue = GETJSAMPLE(*inptr++);
*outptr++ = (JSAMPLE)invalue;
*outptr++ = (JSAMPLE)((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2);
for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
/* General case: 3/4 * nearer pixel + 1/4 * further pixel */
invalue = GETJSAMPLE(*inptr++) * 3;
*outptr++ = (JSAMPLE)((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2);
*outptr++ = (JSAMPLE)((invalue + GETJSAMPLE(*inptr) + 2) >> 2);
}
/* Special case for last column */
invalue = GETJSAMPLE(*inptr);
*outptr++ = (JSAMPLE)((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2);
*outptr++ = (JSAMPLE)invalue;
}
}
/*
* Fancy processing for 1:1 horizontal and 2:1 vertical (4:4:0 subsampling).
*
* This is a less common case, but it can be encountered when losslessly
* rotating/transposing a JPEG file that uses 4:2:2 chroma subsampling.
*/
METHODDEF(void)
h1v2_fancy_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr,
JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
JSAMPARRAY output_data = *output_data_ptr;
JSAMPROW inptr0, inptr1, outptr;
#if BITS_IN_JSAMPLE == 8
int thiscolsum;
#else
JLONG thiscolsum;
#endif
JDIMENSION colctr;
int inrow, outrow, v;
inrow = outrow = 0;
while (outrow < cinfo->max_v_samp_factor) {
for (v = 0; v < 2; v++) {
/* inptr0 points to nearest input row, inptr1 points to next nearest */
inptr0 = input_data[inrow];
if (v == 0) /* next nearest is row above */
inptr1 = input_data[inrow - 1];
else /* next nearest is row below */
inptr1 = input_data[inrow + 1];
outptr = output_data[outrow++];
for (colctr = 0; colctr < compptr->downsampled_width; colctr++) {
thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
*outptr++ = (JSAMPLE)((thiscolsum + 1) >> 2);
}
}
inrow++;
}
}
/*
* Fancy processing for the common case of 2:1 horizontal and 2:1 vertical.
* Again a triangle filter; see comments for h2v1 case, above.
*
* It is OK for us to reference the adjacent input rows because we demanded
* context from the main buffer controller (see initialization code).
*/
METHODDEF(void)
h2v2_fancy_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr,
JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
JSAMPARRAY output_data = *output_data_ptr;
register JSAMPROW inptr0, inptr1, outptr;
#if BITS_IN_JSAMPLE == 8
register int thiscolsum, lastcolsum, nextcolsum;
#else
register JLONG thiscolsum, lastcolsum, nextcolsum;
#endif
register JDIMENSION colctr;
int inrow, outrow, v;
inrow = outrow = 0;
while (outrow < cinfo->max_v_samp_factor) {
for (v = 0; v < 2; v++) {
/* inptr0 points to nearest input row, inptr1 points to next nearest */
inptr0 = input_data[inrow];
if (v == 0) /* next nearest is row above */
inptr1 = input_data[inrow - 1];
else /* next nearest is row below */
inptr1 = input_data[inrow + 1];
outptr = output_data[outrow++];
/* Special case for first column */
thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
*outptr++ = (JSAMPLE)((thiscolsum * 4 + 8) >> 4);
*outptr++ = (JSAMPLE)((thiscolsum * 3 + nextcolsum + 7) >> 4);
lastcolsum = thiscolsum; thiscolsum = nextcolsum;
for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
/* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */
/* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */
nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
*outptr++ = (JSAMPLE)((thiscolsum * 3 + lastcolsum + 8) >> 4);
*outptr++ = (JSAMPLE)((thiscolsum * 3 + nextcolsum + 7) >> 4);
lastcolsum = thiscolsum; thiscolsum = nextcolsum;
}
/* Special case for last column */
*outptr++ = (JSAMPLE)((thiscolsum * 3 + lastcolsum + 8) >> 4);
*outptr++ = (JSAMPLE)((thiscolsum * 4 + 7) >> 4);
}
inrow++;
}
}
/*
* Module initialization routine for upsampling.
*/
GLOBAL(void)
jinit_upsampler(j_decompress_ptr cinfo)
{
my_upsample_ptr upsample;
int ci;
jpeg_component_info *compptr;
boolean need_buffer, do_fancy;
int h_in_group, v_in_group, h_out_group, v_out_group;
if (!cinfo->master->jinit_upsampler_no_alloc) {
upsample = (my_upsample_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
sizeof(my_upsampler));
cinfo->upsample = (struct jpeg_upsampler *)upsample;
upsample->pub.start_pass = start_pass_upsample;
upsample->pub.upsample = sep_upsample;
upsample->pub.need_context_rows = FALSE; /* until we find out differently */
} else
upsample = (my_upsample_ptr)cinfo->upsample;
if (cinfo->CCIR601_sampling) /* this isn't supported */
ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
/* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
* so don't ask for it.
*/
do_fancy = cinfo->do_fancy_upsampling && cinfo->_min_DCT_scaled_size > 1;
/* Verify we can handle the sampling factors, select per-component methods,
* and create storage as needed.
*/
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
/* Compute size of an "input group" after IDCT scaling. This many samples
* are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
*/
h_in_group = (compptr->h_samp_factor * compptr->_DCT_scaled_size) /
cinfo->_min_DCT_scaled_size;
v_in_group = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
cinfo->_min_DCT_scaled_size;
h_out_group = cinfo->max_h_samp_factor;
v_out_group = cinfo->max_v_samp_factor;
upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
need_buffer = TRUE;
if (!compptr->component_needed) {
/* Don't bother to upsample an uninteresting component. */
upsample->methods[ci] = noop_upsample;
need_buffer = FALSE;
} else if (h_in_group == h_out_group && v_in_group == v_out_group) {
/* Fullsize components can be processed without any work. */
upsample->methods[ci] = fullsize_upsample;
need_buffer = FALSE;
} else if (h_in_group * 2 == h_out_group && v_in_group == v_out_group) {
/* Special cases for 2h1v upsampling */
if (do_fancy && compptr->downsampled_width > 2) {
if (jsimd_can_h2v1_fancy_upsample())
upsample->methods[ci] = jsimd_h2v1_fancy_upsample;
else
upsample->methods[ci] = h2v1_fancy_upsample;
} else {
if (jsimd_can_h2v1_upsample())
upsample->methods[ci] = jsimd_h2v1_upsample;
else
upsample->methods[ci] = h2v1_upsample;
}
} else if (h_in_group == h_out_group &&
v_in_group * 2 == v_out_group && do_fancy) {
/* Non-fancy upsampling is handled by the generic method */
upsample->methods[ci] = h1v2_fancy_upsample;
upsample->pub.need_context_rows = TRUE;
} else if (h_in_group * 2 == h_out_group &&
v_in_group * 2 == v_out_group) {
/* Special cases for 2h2v upsampling */
if (do_fancy && compptr->downsampled_width > 2) {
if (jsimd_can_h2v2_fancy_upsample())
upsample->methods[ci] = jsimd_h2v2_fancy_upsample;
else
upsample->methods[ci] = h2v2_fancy_upsample;
upsample->pub.need_context_rows = TRUE;
} else {
if (jsimd_can_h2v2_upsample())
upsample->methods[ci] = jsimd_h2v2_upsample;
else
upsample->methods[ci] = h2v2_upsample;
}
} else if ((h_out_group % h_in_group) == 0 &&
(v_out_group % v_in_group) == 0) {
/* Generic integral-factors upsampling method */
#if defined(__mips__)
if (jsimd_can_int_upsample())
upsample->methods[ci] = jsimd_int_upsample;
else
#endif
upsample->methods[ci] = int_upsample;
upsample->h_expand[ci] = (UINT8)(h_out_group / h_in_group);
upsample->v_expand[ci] = (UINT8)(v_out_group / v_in_group);
} else
ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
if (need_buffer && !cinfo->master->jinit_upsampler_no_alloc) {
upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
((j_common_ptr)cinfo, JPOOL_IMAGE,
(JDIMENSION)jround_up((long)cinfo->output_width,
(long)cinfo->max_h_samp_factor),
(JDIMENSION)cinfo->max_v_samp_factor);
}
}
}
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