/*
 * 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 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 * 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);
		}
	}
}
