src/third_party/libjpeg-turbo/jdsample.c - cobalt - Git at Google

 /*
  * 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);
     }
   }
 }
	/*
	* 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);
	}
	}
	}