path: root/src/transupp.c

/*
 * transupp.c
 *
 * Copyright (C) 1997-2009, Thomas G. Lane, Guido Vollbeding.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains image transformation routines and other utility code
 * used by the jpegtran sample application.  These are NOT part of the core
 * JPEG library.  But we keep these routines separate from jpegtran.c to
 * ease the task of maintaining jpegtran-like programs that have other user
 * interfaces.
 */

/* Although this file really shouldn't have access to the library internals,
 * it's helpful to let it call jround_up() and jcopy_block_row().
 */
#define JPEG_INTERNALS

#include <stddef.h>
#include <stdlib.h>
#include <sys/types.h>
#include <stdio.h>

#include <string.h>
#define MEMZERO(target,size)  memset((void *)(target), 0, (size_t)(size))
#define MEMCOPY(dest,src,size)  memcpy((void *)(dest), (const void *)(src), (size_t)(size))
#define SIZEOF(object)  ((size_t) sizeof(object))
#define JFREAD(file,buf,sizeofbuf)  \
	((size_t) fread((void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))
#define JFWRITE(file,buf,sizeofbuf)  \
	((size_t) fwrite((const void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))
#include "jpeglib.h"
#include "transupp.h"		/* My own external interface */
#include <ctype.h>		/* to declare isdigit() */


#if TRANSFORMS_SUPPORTED

/*
 * Lossless image transformation routines.  These routines work on DCT
 * coefficient arrays and thus do not require any lossy decompression
 * or recompression of the image.
 * Thanks to Guido Vollbeding for the initial design and code of this feature,
 * and to Ben Jackson for introducing the cropping feature.
 *
 * Horizontal flipping is done in-place, using a single top-to-bottom
 * pass through the virtual source array.  It will thus be much the
 * fastest option for images larger than main memory.
 *
 * The other routines require a set of destination virtual arrays, so they
 * need twice as much memory as jpegtran normally does.  The destination
 * arrays are always written in normal scan order (top to bottom) because
 * the virtual array manager expects this.  The source arrays will be scanned
 * in the corresponding order, which means multiple passes through the source
 * arrays for most of the transforms.  That could result in much thrashing
 * if the image is larger than main memory.
 *
 * If cropping or trimming is involved, the destination arrays may be smaller
 * than the source arrays.  Note it is not possible to do horizontal flip
 * in-place when a nonzero Y crop offset is specified, since we'd have to move
 * data from one block row to another but the virtual array manager doesn't
 * guarantee we can touch more than one row at a time.  So in that case,
 * we have to use a separate destination array.
 *
 * Some notes about the operating environment of the individual transform
 * routines:
 * 1. Both the source and destination virtual arrays are allocated from the
 *    source JPEG object, and therefore should be manipulated by calling the
 *    source's memory manager.
 * 2. The destination's component count should be used.  It may be smaller
 *    than the source's when forcing to grayscale.
 * 3. Likewise the destination's sampling factors should be used.  When
 *    forcing to grayscale the destination's sampling factors will be all 1,
 *    and we may as well take that as the effective iMCU size.
 * 4. When "trim" is in effect, the destination's dimensions will be the
 *    trimmed values but the source's will be untrimmed.
 * 5. When "crop" is in effect, the destination's dimensions will be the
 *    cropped values but the source's will be uncropped.  Each transform
 *    routine is responsible for picking up source data starting at the
 *    correct X and Y offset for the crop region.  (The X and Y offsets
 *    passed to the transform routines are measured in iMCU blocks of the
 *    destination.)
 * 6. All the routines assume that the source and destination buffers are
 *    padded out to a full iMCU boundary.  This is true, although for the
 *    source buffer it is an undocumented property of jdcoefct.c.
 */

LOCAL(void)
do_flip_h_no_crop(j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
		  JDIMENSION x_crop_offset, jvirt_barray_ptr * src_coef_arrays)
/* Horizontal flip; done in-place, so no separate dest array is required.
 * NB: this only works when y_crop_offset is zero.
 */
{
	JDIMENSION MCU_cols, comp_width, blk_x, blk_y, x_crop_blocks;
	int ci, k, offset_y;
	JBLOCKARRAY buffer;
	JCOEFPTR ptr1, ptr2;
	JCOEF temp1, temp2;
	jpeg_component_info *compptr;

	/* Horizontal mirroring of DCT blocks is accomplished by swapping
	 * pairs of blocks in-place.  Within a DCT block, we perform horizontal
	 * mirroring by changing the signs of odd-numbered columns.
	 * Partial iMCUs at the right edge are left untouched.
	 */
	MCU_cols = srcinfo->output_width / (dstinfo->max_h_samp_factor * dstinfo->min_DCT_h_scaled_size);

	for (ci = 0; ci < dstinfo->num_components; ci++) {
		compptr = dstinfo->comp_info + ci;
		comp_width = MCU_cols * compptr->h_samp_factor;
		x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
		for (blk_y = 0; blk_y < compptr->height_in_blocks; blk_y += compptr->v_samp_factor) {
			buffer = (*srcinfo->mem->access_virt_barray)
			    ((j_common_ptr) srcinfo, src_coef_arrays[ci], blk_y,
			     (JDIMENSION) compptr->v_samp_factor, TRUE);
			for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
				/* Do the mirroring */
				for (blk_x = 0; blk_x * 2 < comp_width; blk_x++) {
					ptr1 = buffer[offset_y][blk_x];
					ptr2 = buffer[offset_y][comp_width - blk_x - 1];
					/* this unrolled loop doesn't need to know which row it's on... */
					for (k = 0; k < DCTSIZE2; k += 2) {
						temp1 = *ptr1;	/* swap even column */
						temp2 = *ptr2;
						*ptr1++ = temp2;
						*ptr2++ = temp1;
						temp1 = *ptr1;	/* swap odd column with sign change */
						temp2 = *ptr2;
						*ptr1++ = -temp2;
						*ptr2++ = -temp1;
					}
				}
				if (x_crop_blocks > 0) {
					/* Now left-justify the portion of the data to be kept.
					 * We can't use a single jcopy_block_row() call because that routine
					 * depends on memcpy(), whose behavior is unspecified for overlapping
					 * source and destination areas.  Sigh.
					 */
					for (blk_x = 0; blk_x < compptr->width_in_blocks; blk_x++) {
						jcopy_block_row(buffer[offset_y] + blk_x + x_crop_blocks,
								buffer[offset_y] + blk_x, (JDIMENSION) 1);
					}
				}
			}
		}
	}
}


LOCAL(void)
do_flip_v(j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
	  JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
	  jvirt_barray_ptr * src_coef_arrays, jvirt_barray_ptr * dst_coef_arrays)
/* Vertical flip */
{
	JDIMENSION MCU_rows, comp_height, dst_blk_x, dst_blk_y;
	JDIMENSION x_crop_blocks, y_crop_blocks;
	int ci, i, j, offset_y;
	JBLOCKARRAY src_buffer, dst_buffer;
	JBLOCKROW src_row_ptr, dst_row_ptr;
	JCOEFPTR src_ptr, dst_ptr;
	jpeg_component_info *compptr;

	/* We output into a separate array because we can't touch different
	 * rows of the source virtual array simultaneously.  Otherwise, this
	 * is a pretty straightforward analog of horizontal flip.
	 * Within a DCT block, vertical mirroring is done by changing the signs
	 * of odd-numbered rows.
	 * Partial iMCUs at the bottom edge are copied verbatim.
	 */
	MCU_rows = srcinfo->output_height / (dstinfo->max_v_samp_factor * dstinfo->min_DCT_v_scaled_size);

	for (ci = 0; ci < dstinfo->num_components; ci++) {
		compptr = dstinfo->comp_info + ci;
		comp_height = MCU_rows * compptr->v_samp_factor;
		x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
		y_crop_blocks = y_crop_offset * compptr->v_samp_factor;
		for (dst_blk_y = 0; dst_blk_y < compptr->height_in_blocks; dst_blk_y += compptr->v_samp_factor) {
			dst_buffer = (*srcinfo->mem->access_virt_barray)
			    ((j_common_ptr) srcinfo, dst_coef_arrays[ci], dst_blk_y,
			     (JDIMENSION) compptr->v_samp_factor, TRUE);
			if (y_crop_blocks + dst_blk_y < comp_height) {
				/* Row is within the mirrorable area. */
				src_buffer = (*srcinfo->mem->access_virt_barray)
				    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
				     comp_height - y_crop_blocks - dst_blk_y -
				     (JDIMENSION) compptr->v_samp_factor, (JDIMENSION) compptr->v_samp_factor, FALSE);
			} else {
				/* Bottom-edge blocks will be copied verbatim. */
				src_buffer = (*srcinfo->mem->access_virt_barray)
				    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
				     dst_blk_y + y_crop_blocks, (JDIMENSION) compptr->v_samp_factor, FALSE);
			}
			for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
				if (y_crop_blocks + dst_blk_y < comp_height) {
					/* Row is within the mirrorable area. */
					dst_row_ptr = dst_buffer[offset_y];
					src_row_ptr = src_buffer[compptr->v_samp_factor - offset_y - 1];
					src_row_ptr += x_crop_blocks;
					for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks; dst_blk_x++) {
						dst_ptr = dst_row_ptr[dst_blk_x];
						src_ptr = src_row_ptr[dst_blk_x];
						for (i = 0; i < DCTSIZE; i += 2) {
							/* copy even row */
							for (j = 0; j < DCTSIZE; j++)
								*dst_ptr++ = *src_ptr++;
							/* copy odd row with sign change */
							for (j = 0; j < DCTSIZE; j++)
								*dst_ptr++ = -*src_ptr++;
						}
					}
				} else {
					/* Just copy row verbatim. */
					jcopy_block_row(src_buffer[offset_y] + x_crop_blocks,
							dst_buffer[offset_y], compptr->width_in_blocks);
				}
			}
		}
	}
}


LOCAL(void)
do_transpose(j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
	     JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
	     jvirt_barray_ptr * src_coef_arrays, jvirt_barray_ptr * dst_coef_arrays)
/* Transpose source into destination */
{
	JDIMENSION dst_blk_x, dst_blk_y, x_crop_blocks, y_crop_blocks;
	int ci, i, j, offset_x, offset_y;
	JBLOCKARRAY src_buffer, dst_buffer;
	JCOEFPTR src_ptr, dst_ptr;
	jpeg_component_info *compptr;

	/* Transposing pixels within a block just requires transposing the
	 * DCT coefficients.
	 * Partial iMCUs at the edges require no special treatment; we simply
	 * process all the available DCT blocks for every component.
	 */
	for (ci = 0; ci < dstinfo->num_components; ci++) {
		compptr = dstinfo->comp_info + ci;
		x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
		y_crop_blocks = y_crop_offset * compptr->v_samp_factor;
		for (dst_blk_y = 0; dst_blk_y < compptr->height_in_blocks; dst_blk_y += compptr->v_samp_factor) {
			dst_buffer = (*srcinfo->mem->access_virt_barray)
			    ((j_common_ptr) srcinfo, dst_coef_arrays[ci], dst_blk_y,
			     (JDIMENSION) compptr->v_samp_factor, TRUE);
			for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
				for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks;
				     dst_blk_x += compptr->h_samp_factor) {
					src_buffer = (*srcinfo->mem->access_virt_barray)
					    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
					     dst_blk_x + x_crop_blocks, (JDIMENSION) compptr->h_samp_factor, FALSE);
					for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {
						dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];
						src_ptr = src_buffer[offset_x][dst_blk_y + offset_y + y_crop_blocks];
						for (i = 0; i < DCTSIZE; i++)
							for (j = 0; j < DCTSIZE; j++)
								dst_ptr[j * DCTSIZE + i] = src_ptr[i * DCTSIZE + j];
					}
				}
			}
		}
	}
}


LOCAL(void)
do_rot_90(j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
	  JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
	  jvirt_barray_ptr * src_coef_arrays, jvirt_barray_ptr * dst_coef_arrays)
/* 90 degree rotation is equivalent to
 *   1. Transposing the image;
 *   2. Horizontal mirroring.
 * These two steps are merged into a single processing routine.
 */
{
	JDIMENSION MCU_cols, comp_width, dst_blk_x, dst_blk_y;
	JDIMENSION x_crop_blocks, y_crop_blocks;
	int ci, i, j, offset_x, offset_y;
	JBLOCKARRAY src_buffer, dst_buffer;
	JCOEFPTR src_ptr, dst_ptr;
	jpeg_component_info *compptr;

	/* Because of the horizontal mirror step, we can't process partial iMCUs
	 * at the (output) right edge properly.  They just get transposed and
	 * not mirrored.
	 */
	MCU_cols = srcinfo->output_height / (dstinfo->max_h_samp_factor * dstinfo->min_DCT_h_scaled_size);

	for (ci = 0; ci < dstinfo->num_components; ci++) {
		compptr = dstinfo->comp_info + ci;
		comp_width = MCU_cols * compptr->h_samp_factor;
		x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
		y_crop_blocks = y_crop_offset * compptr->v_samp_factor;
		for (dst_blk_y = 0; dst_blk_y < compptr->height_in_blocks; dst_blk_y += compptr->v_samp_factor) {
			dst_buffer = (*srcinfo->mem->access_virt_barray)
			    ((j_common_ptr) srcinfo, dst_coef_arrays[ci], dst_blk_y,
			     (JDIMENSION) compptr->v_samp_factor, TRUE);
			for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
				for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks;
				     dst_blk_x += compptr->h_samp_factor) {
					if (x_crop_blocks + dst_blk_x < comp_width) {
						/* Block is within the mirrorable area. */
						src_buffer = (*srcinfo->mem->access_virt_barray)
						    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
						     comp_width - x_crop_blocks - dst_blk_x -
						     (JDIMENSION) compptr->h_samp_factor,
						     (JDIMENSION) compptr->h_samp_factor, FALSE);
					} else {
						/* Edge blocks are transposed but not mirrored. */
						src_buffer = (*srcinfo->mem->access_virt_barray)
						    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
						     dst_blk_x + x_crop_blocks,
						     (JDIMENSION) compptr->h_samp_factor, FALSE);
					}
					for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {
						dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];
						if (x_crop_blocks + dst_blk_x < comp_width) {
							/* Block is within the mirrorable area. */
							src_ptr = src_buffer[compptr->h_samp_factor - offset_x - 1]
							    [dst_blk_y + offset_y + y_crop_blocks];
							for (i = 0; i < DCTSIZE; i++) {
								for (j = 0; j < DCTSIZE; j++)
									dst_ptr[j * DCTSIZE + i] =
									    src_ptr[i * DCTSIZE + j];
								i++;
								for (j = 0; j < DCTSIZE; j++)
									dst_ptr[j * DCTSIZE + i] =
									    -src_ptr[i * DCTSIZE + j];
							}
						} else {
							/* Edge blocks are transposed but not mirrored. */
							src_ptr = src_buffer[offset_x]
							    [dst_blk_y + offset_y + y_crop_blocks];
							for (i = 0; i < DCTSIZE; i++)
								for (j = 0; j < DCTSIZE; j++)
									dst_ptr[j * DCTSIZE + i] =
									    src_ptr[i * DCTSIZE + j];
						}
					}
				}
			}
		}
	}
}


LOCAL(void)
do_rot_270(j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
	   JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
	   jvirt_barray_ptr * src_coef_arrays, jvirt_barray_ptr * dst_coef_arrays)
/* 270 degree rotation is equivalent to
 *   1. Horizontal mirroring;
 *   2. Transposing the image.
 * These two steps are merged into a single processing routine.
 */
{
	JDIMENSION MCU_rows, comp_height, dst_blk_x, dst_blk_y;
	JDIMENSION x_crop_blocks, y_crop_blocks;
	int ci, i, j, offset_x, offset_y;
	JBLOCKARRAY src_buffer, dst_buffer;
	JCOEFPTR src_ptr, dst_ptr;
	jpeg_component_info *compptr;

	/* Because of the horizontal mirror step, we can't process partial iMCUs
	 * at the (output) bottom edge properly.  They just get transposed and
	 * not mirrored.
	 */
	MCU_rows = srcinfo->output_width / (dstinfo->max_v_samp_factor * dstinfo->min_DCT_v_scaled_size);

	for (ci = 0; ci < dstinfo->num_components; ci++) {
		compptr = dstinfo->comp_info + ci;
		comp_height = MCU_rows * compptr->v_samp_factor;
		x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
		y_crop_blocks = y_crop_offset * compptr->v_samp_factor;
		for (dst_blk_y = 0; dst_blk_y < compptr->height_in_blocks; dst_blk_y += compptr->v_samp_factor) {
			dst_buffer = (*srcinfo->mem->access_virt_barray)
			    ((j_common_ptr) srcinfo, dst_coef_arrays[ci], dst_blk_y,
			     (JDIMENSION) compptr->v_samp_factor, TRUE);
			for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
				for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks;
				     dst_blk_x += compptr->h_samp_factor) {
					src_buffer = (*srcinfo->mem->access_virt_barray)
					    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
					     dst_blk_x + x_crop_blocks, (JDIMENSION) compptr->h_samp_factor, FALSE);
					for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {
						dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];
						if (y_crop_blocks + dst_blk_y < comp_height) {
							/* Block is within the mirrorable area. */
							src_ptr = src_buffer[offset_x]
							    [comp_height - y_crop_blocks - dst_blk_y - offset_y - 1];
							for (i = 0; i < DCTSIZE; i++) {
								for (j = 0; j < DCTSIZE; j++) {
									dst_ptr[j * DCTSIZE + i] =
									    src_ptr[i * DCTSIZE + j];
									j++;
									dst_ptr[j * DCTSIZE + i] =
									    -src_ptr[i * DCTSIZE + j];
								}
							}
						} else {
							/* Edge blocks are transposed but not mirrored. */
							src_ptr = src_buffer[offset_x]
							    [dst_blk_y + offset_y + y_crop_blocks];
							for (i = 0; i < DCTSIZE; i++)
								for (j = 0; j < DCTSIZE; j++)
									dst_ptr[j * DCTSIZE + i] =
									    src_ptr[i * DCTSIZE + j];
						}
					}
				}
			}
		}
	}
}


LOCAL(void)
do_rot_180(j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
	   JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
	   jvirt_barray_ptr * src_coef_arrays, jvirt_barray_ptr * dst_coef_arrays)
/* 180 degree rotation is equivalent to
 *   1. Vertical mirroring;
 *   2. Horizontal mirroring.
 * These two steps are merged into a single processing routine.
 */
{
	JDIMENSION MCU_cols, MCU_rows, comp_width, comp_height, dst_blk_x, dst_blk_y;
	JDIMENSION x_crop_blocks, y_crop_blocks;
	int ci, i, j, offset_y;
	JBLOCKARRAY src_buffer, dst_buffer;
	JBLOCKROW src_row_ptr, dst_row_ptr;
	JCOEFPTR src_ptr, dst_ptr;
	jpeg_component_info *compptr;

	MCU_cols = srcinfo->output_width / (dstinfo->max_h_samp_factor * dstinfo->min_DCT_h_scaled_size);
	MCU_rows = srcinfo->output_height / (dstinfo->max_v_samp_factor * dstinfo->min_DCT_v_scaled_size);

	for (ci = 0; ci < dstinfo->num_components; ci++) {
		compptr = dstinfo->comp_info + ci;
		comp_width = MCU_cols * compptr->h_samp_factor;
		comp_height = MCU_rows * compptr->v_samp_factor;
		x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
		y_crop_blocks = y_crop_offset * compptr->v_samp_factor;
		for (dst_blk_y = 0; dst_blk_y < compptr->height_in_blocks; dst_blk_y += compptr->v_samp_factor) {
			dst_buffer = (*srcinfo->mem->access_virt_barray)
			    ((j_common_ptr) srcinfo, dst_coef_arrays[ci], dst_blk_y,
			     (JDIMENSION) compptr->v_samp_factor, TRUE);
			if (y_crop_blocks + dst_blk_y < comp_height) {
				/* Row is within the vertically mirrorable area. */
				src_buffer = (*srcinfo->mem->access_virt_barray)
				    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
				     comp_height - y_crop_blocks - dst_blk_y -
				     (JDIMENSION) compptr->v_samp_factor, (JDIMENSION) compptr->v_samp_factor, FALSE);
			} else {
				/* Bottom-edge rows are only mirrored horizontally. */
				src_buffer = (*srcinfo->mem->access_virt_barray)
				    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
				     dst_blk_y + y_crop_blocks, (JDIMENSION) compptr->v_samp_factor, FALSE);
			}
			for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
				dst_row_ptr = dst_buffer[offset_y];
				if (y_crop_blocks + dst_blk_y < comp_height) {
					/* Row is within the mirrorable area. */
					src_row_ptr = src_buffer[compptr->v_samp_factor - offset_y - 1];
					for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks; dst_blk_x++) {
						dst_ptr = dst_row_ptr[dst_blk_x];
						if (x_crop_blocks + dst_blk_x < comp_width) {
							/* Process the blocks that can be mirrored both ways. */
							src_ptr =
							    src_row_ptr[comp_width - x_crop_blocks - dst_blk_x - 1];
							for (i = 0; i < DCTSIZE; i += 2) {
								/* For even row, negate every odd column. */
								for (j = 0; j < DCTSIZE; j += 2) {
									*dst_ptr++ = *src_ptr++;
									*dst_ptr++ = -*src_ptr++;
								}
								/* For odd row, negate every even column. */
								for (j = 0; j < DCTSIZE; j += 2) {
									*dst_ptr++ = -*src_ptr++;
									*dst_ptr++ = *src_ptr++;
								}
							}
						} else {
							/* Any remaining right-edge blocks are only mirrored vertically. */
							src_ptr = src_row_ptr[x_crop_blocks + dst_blk_x];
							for (i = 0; i < DCTSIZE; i += 2) {
								for (j = 0; j < DCTSIZE; j++)
									*dst_ptr++ = *src_ptr++;
								for (j = 0; j < DCTSIZE; j++)
									*dst_ptr++ = -*src_ptr++;
							}
						}
					}
				} else {
					/* Remaining rows are just mirrored horizontally. */
					src_row_ptr = src_buffer[offset_y];
					for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks; dst_blk_x++) {
						if (x_crop_blocks + dst_blk_x < comp_width) {
							/* Process the blocks that can be mirrored. */
							dst_ptr = dst_row_ptr[dst_blk_x];
							src_ptr =
							    src_row_ptr[comp_width - x_crop_blocks - dst_blk_x - 1];
							for (i = 0; i < DCTSIZE2; i += 2) {
								*dst_ptr++ = *src_ptr++;
								*dst_ptr++ = -*src_ptr++;
							}
						} else {
							/* Any remaining right-edge blocks are only copied. */
							jcopy_block_row(src_row_ptr + dst_blk_x + x_crop_blocks,
									dst_row_ptr + dst_blk_x, (JDIMENSION) 1);
						}
					}
				}
			}
		}
	}
}


LOCAL(void)
do_transverse(j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
	      JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
	      jvirt_barray_ptr * src_coef_arrays, jvirt_barray_ptr * dst_coef_arrays)
/* Transverse transpose is equivalent to
 *   1. 180 degree rotation;
 *   2. Transposition;
 * or
 *   1. Horizontal mirroring;
 *   2. Transposition;
 *   3. Horizontal mirroring.
 * These steps are merged into a single processing routine.
 */
{
	JDIMENSION MCU_cols, MCU_rows, comp_width, comp_height, dst_blk_x, dst_blk_y;
	JDIMENSION x_crop_blocks, y_crop_blocks;
	int ci, i, j, offset_x, offset_y;
	JBLOCKARRAY src_buffer, dst_buffer;
	JCOEFPTR src_ptr, dst_ptr;
	jpeg_component_info *compptr;

	MCU_cols = srcinfo->output_height / (dstinfo->max_h_samp_factor * dstinfo->min_DCT_h_scaled_size);
	MCU_rows = srcinfo->output_width / (dstinfo->max_v_samp_factor * dstinfo->min_DCT_v_scaled_size);

	for (ci = 0; ci < dstinfo->num_components; ci++) {
		compptr = dstinfo->comp_info + ci;
		comp_width = MCU_cols * compptr->h_samp_factor;
		comp_height = MCU_rows * compptr->v_samp_factor;
		x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
		y_crop_blocks = y_crop_offset * compptr->v_samp_factor;
		for (dst_blk_y = 0; dst_blk_y < compptr->height_in_blocks; dst_blk_y += compptr->v_samp_factor) {
			dst_buffer = (*srcinfo->mem->access_virt_barray)
			    ((j_common_ptr) srcinfo, dst_coef_arrays[ci], dst_blk_y,
			     (JDIMENSION) compptr->v_samp_factor, TRUE);
			for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
				for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks;
				     dst_blk_x += compptr->h_samp_factor) {
					if (x_crop_blocks + dst_blk_x < comp_width) {
						/* Block is within the mirrorable area. */
						src_buffer = (*srcinfo->mem->access_virt_barray)
						    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
						     comp_width - x_crop_blocks - dst_blk_x -
						     (JDIMENSION) compptr->h_samp_factor,
						     (JDIMENSION) compptr->h_samp_factor, FALSE);
					} else {
						src_buffer = (*srcinfo->mem->access_virt_barray)
						    ((j_common_ptr) srcinfo, src_coef_arrays[ci],
						     dst_blk_x + x_crop_blocks,
						     (JDIMENSION) compptr->h_samp_factor, FALSE);
					}
					for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {
						dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];
						if (y_crop_blocks + dst_blk_y < comp_height) {
							if (x_crop_blocks + dst_blk_x < comp_width) {
								/* Block is within the mirrorable area. */
								src_ptr =
								    src_buffer[compptr->h_samp_factor - offset_x - 1]
								    [comp_height - y_crop_blocks - dst_blk_y -
								     offset_y - 1];
								for (i = 0; i < DCTSIZE; i++) {
									for (j = 0; j < DCTSIZE; j++) {
										dst_ptr[j * DCTSIZE + i] =
										    src_ptr[i * DCTSIZE + j];
										j++;
										dst_ptr[j * DCTSIZE + i] =
										    -src_ptr[i * DCTSIZE + j];
									}
									i++;
									for (j = 0; j < DCTSIZE; j++) {
										dst_ptr[j * DCTSIZE + i] =
										    -src_ptr[i * DCTSIZE + j];
										j++;
										dst_ptr[j * DCTSIZE + i] =
										    src_ptr[i * DCTSIZE + j];
									}
								}
							} else {
								/* Right-edge blocks are mirrored in y only */
								src_ptr = src_buffer[offset_x]
								    [comp_height - y_crop_blocks - dst_blk_y -
								     offset_y - 1];
								for (i = 0; i < DCTSIZE; i++) {
									for (j = 0; j < DCTSIZE; j++) {
										dst_ptr[j * DCTSIZE + i] =
										    src_ptr[i * DCTSIZE + j];
										j++;
										dst_ptr[j * DCTSIZE + i] =
										    -src_ptr[i * DCTSIZE + j];
									}
								}
							}
						} else {
							if (x_crop_blocks + dst_blk_x < comp_width) {
								/* Bottom-edge blocks are mirrored in x only */
								src_ptr =
								    src_buffer[compptr->h_samp_factor - offset_x - 1]
								    [dst_blk_y + offset_y + y_crop_blocks];
								for (i = 0; i < DCTSIZE; i++) {
									for (j = 0; j < DCTSIZE; j++)
										dst_ptr[j * DCTSIZE + i] =
										    src_ptr[i * DCTSIZE + j];
									i++;
									for (j = 0; j < DCTSIZE; j++)
										dst_ptr[j * DCTSIZE + i] =
										    -src_ptr[i * DCTSIZE + j];
								}
							} else {
								/* At lower right corner, just transpose, no mirroring */
								src_ptr = src_buffer[offset_x]
								    [dst_blk_y + offset_y + y_crop_blocks];
								for (i = 0; i < DCTSIZE; i++)
									for (j = 0; j < DCTSIZE; j++)
										dst_ptr[j * DCTSIZE + i] =
										    src_ptr[i * DCTSIZE + j];
							}
						}
					}
				}
			}
		}
	}
}


/* Parse an unsigned integer: subroutine for jtransform_parse_crop_spec.
 * Returns TRUE if valid integer found, FALSE if not.
 * *strptr is advanced over the digit string, and *result is set to its value.
 */

LOCAL(boolean)
    jt_read_integer(const char **strptr, JDIMENSION * result)
{
	const char *ptr = *strptr;
	JDIMENSION val = 0;

	for (; isdigit(*ptr); ptr++) {
		val = val * 10 + (JDIMENSION) (*ptr - '0');
	}
	*result = val;
	if (ptr == *strptr)
		return FALSE;	/* oops, no digits */
	*strptr = ptr;
	return TRUE;
}


/* Parse a crop specification (written in X11 geometry style).
 * The routine returns TRUE if the spec string is valid, FALSE if not.
 *
 * The crop spec string should have the format
 *	<width>x<height>{+-}<xoffset>{+-}<yoffset>
 * where width, height, xoffset, and yoffset are unsigned integers.
 * Each of the elements can be omitted to indicate a default value.
 * (A weakness of this style is that it is not possible to omit xoffset
 * while specifying yoffset, since they look alike.)
 *
 * This code is loosely based on XParseGeometry from the X11 distribution.
 */

GLOBAL(boolean)
    jtransform_parse_crop_spec(jpeg_transform_info * info, const char *spec)
{
	info->crop = FALSE;
	info->crop_width_set = JCROP_UNSET;
	info->crop_height_set = JCROP_UNSET;
	info->crop_xoffset_set = JCROP_UNSET;
	info->crop_yoffset_set = JCROP_UNSET;

	if (isdigit(*spec)) {
		/* fetch width */
		if (!jt_read_integer(&spec, &info->crop_width))
			return FALSE;
		info->crop_width_set = JCROP_POS;
	}
	if (*spec == 'x' || *spec == 'X') {
		/* fetch height */
		spec++;
		if (!jt_read_integer(&spec, &info->crop_height))
			return FALSE;
		info->crop_height_set = JCROP_POS;
	}
	if (*spec == '+' || *spec == '-') {
		/* fetch xoffset */
		info->crop_xoffset_set = (*spec == '-') ? JCROP_NEG : JCROP_POS;
		spec++;
		if (!jt_read_integer(&spec, &info->crop_xoffset))
			return FALSE;
	}
	if (*spec == '+' || *spec == '-') {
		/* fetch yoffset */
		info->crop_yoffset_set = (*spec == '-') ? JCROP_NEG : JCROP_POS;
		spec++;
		if (!jt_read_integer(&spec, &info->crop_yoffset))
			return FALSE;
	}
	/* We had better have gotten to the end of the string. */
	if (*spec != '\0')
		return FALSE;
	info->crop = TRUE;
	return TRUE;
}


/* Trim off any partial iMCUs on the indicated destination edge */

LOCAL(void)
    trim_right_edge(jpeg_transform_info * info, JDIMENSION full_width)
{
	JDIMENSION MCU_cols;

	MCU_cols = info->output_width / info->iMCU_sample_width;
	if (MCU_cols > 0 && info->x_crop_offset + MCU_cols == full_width / info->iMCU_sample_width)
		info->output_width = MCU_cols * info->iMCU_sample_width;
}

LOCAL(void) trim_bottom_edge(jpeg_transform_info * info, JDIMENSION full_height)
{
	JDIMENSION MCU_rows;

	MCU_rows = info->output_height / info->iMCU_sample_height;
	if (MCU_rows > 0 && info->y_crop_offset + MCU_rows == full_height / info->iMCU_sample_height)
		info->output_height = MCU_rows * info->iMCU_sample_height;
}


/* Request any required workspace.
 *
 * This routine figures out the size that the output image will be
 * (which implies that all the transform parameters must be set before
 * it is called).
 *
 * We allocate the workspace virtual arrays from the source decompression
 * object, so that all the arrays (both the original data and the workspace)
 * will be taken into account while making memory management decisions.
 * Hence, this routine must be called after jpeg_read_header (which reads
 * the image dimensions) and before jpeg_read_coefficients (which realizes
 * the source's virtual arrays).
 */

GLOBAL(boolean)
    jtransform_request_workspace(j_decompress_ptr srcinfo, jpeg_transform_info * info)
{
	jvirt_barray_ptr *coef_arrays;
	boolean need_workspace, transpose_it;
	jpeg_component_info *compptr;
	JDIMENSION xoffset, yoffset;
	JDIMENSION width_in_iMCUs, height_in_iMCUs;
	JDIMENSION width_in_blocks, height_in_blocks;
	int ci, h_samp_factor, v_samp_factor;

	/* Determine number of components in output image */
	if (info->force_grayscale && srcinfo->jpeg_color_space == JCS_YCbCr && srcinfo->num_components == 3)
		/* We'll only process the first component */
		info->num_components = 1;
	else
		/* Process all the components */
		info->num_components = srcinfo->num_components;

	/* Compute output image dimensions and related values. */
	jpeg_core_output_dimensions(srcinfo);

	/* If there is only one output component, force the iMCU size to be 1;
	 * else use the source iMCU size.  (This allows us to do the right thing
	 * when reducing color to grayscale, and also provides a handy way of
	 * cleaning up "funny" grayscale images whose sampling factors are not 1x1.)
	 */
	switch (info->transform) {
	case JXFORM_TRANSPOSE:
	case JXFORM_TRANSVERSE:
	case JXFORM_ROT_90:
	case JXFORM_ROT_270:
		info->output_width = srcinfo->output_height;
		info->output_height = srcinfo->output_width;
		if (info->num_components == 1) {
			info->iMCU_sample_width = srcinfo->min_DCT_v_scaled_size;
			info->iMCU_sample_height = srcinfo->min_DCT_h_scaled_size;
		} else {
			info->iMCU_sample_width = srcinfo->max_v_samp_factor * srcinfo->min_DCT_v_scaled_size;
			info->iMCU_sample_height = srcinfo->max_h_samp_factor * srcinfo->min_DCT_h_scaled_size;
		}
		break;
	default:
		info->output_width = srcinfo->output_width;
		info->output_height = srcinfo->output_height;
		if (info->num_components == 1) {
			info->iMCU_sample_width = srcinfo->min_DCT_h_scaled_size;
			info->iMCU_sample_height = srcinfo->min_DCT_v_scaled_size;
		} else {
			info->iMCU_sample_width = srcinfo->max_h_samp_factor * srcinfo->min_DCT_h_scaled_size;
			info->iMCU_sample_height = srcinfo->max_v_samp_factor * srcinfo->min_DCT_v_scaled_size;
		}
		break;
	}

	/* If cropping has been requested, compute the crop area's position and
	 * dimensions, ensuring that its upper left corner falls at an iMCU boundary.
	 */
	if (info->crop) {
		/* Insert default values for unset crop parameters */
		if (info->crop_xoffset_set == JCROP_UNSET)
			info->crop_xoffset = 0;	/* default to +0 */
		if (info->crop_yoffset_set == JCROP_UNSET)
			info->crop_yoffset = 0;	/* default to +0 */
		if (info->crop_xoffset >= info->output_width || info->crop_yoffset >= info->output_height)
			ERREXIT(srcinfo, JERR_BAD_CROP_SPEC);
		if (info->crop_width_set == JCROP_UNSET)
			info->crop_width = info->output_width - info->crop_xoffset;
		if (info->crop_height_set == JCROP_UNSET)
			info->crop_height = info->output_height - info->crop_yoffset;
		/* Ensure parameters are valid */
		if (info->crop_width <= 0 || info->crop_width > info->output_width ||
		    info->crop_height <= 0 || info->crop_height > info->output_height ||
		    info->crop_xoffset > info->output_width - info->crop_width ||
		    info->crop_yoffset > info->output_height - info->crop_height)
			ERREXIT(srcinfo, JERR_BAD_CROP_SPEC);
		/* Convert negative crop offsets into regular offsets */
		if (info->crop_xoffset_set == JCROP_NEG)
			xoffset = info->output_width - info->crop_width - info->crop_xoffset;
		else
			xoffset = info->crop_xoffset;
		if (info->crop_yoffset_set == JCROP_NEG)
			yoffset = info->output_height - info->crop_height - info->crop_yoffset;
		else
			yoffset = info->crop_yoffset;
		/* Now adjust so that upper left corner falls at an iMCU boundary */
		info->output_width = info->crop_width + (xoffset % info->iMCU_sample_width);
		info->output_height = info->crop_height + (yoffset % info->iMCU_sample_height);
		/* Save x/y offsets measured in iMCUs */
		info->x_crop_offset = xoffset / info->iMCU_sample_width;
		info->y_crop_offset = yoffset / info->iMCU_sample_height;
	} else {
		info->x_crop_offset = 0;
		info->y_crop_offset = 0;
	}

	/* Figure out whether we need workspace arrays,
	 * and if so whether they are transposed relative to the source.
	 */
	need_workspace = FALSE;
	transpose_it = FALSE;
	switch (info->transform) {
	case JXFORM_NONE:
		if (info->x_crop_offset != 0 || info->y_crop_offset != 0)
			need_workspace = TRUE;
		/* No workspace needed if neither cropping nor transforming */
		break;
	case JXFORM_FLIP_H:
		if (info->trim)
			trim_right_edge(info, srcinfo->output_width);
		if (info->y_crop_offset != 0)
			need_workspace = TRUE;
		/* do_flip_h_no_crop doesn't need a workspace array */
		break;
	case JXFORM_FLIP_V:
		if (info->trim)
			trim_bottom_edge(info, srcinfo->output_height);
		/* Need workspace arrays having same dimensions as source image. */
		need_workspace = TRUE;
		break;
	case JXFORM_TRANSPOSE:
		/* transpose does NOT have to trim anything */
		/* Need workspace arrays having transposed dimensions. */
		need_workspace = TRUE;
		transpose_it = TRUE;
		break;
	case JXFORM_TRANSVERSE:
		if (info->trim) {
			trim_right_edge(info, srcinfo->output_height);
			trim_bottom_edge(info, srcinfo->output_width);
		}
		/* Need workspace arrays having transposed dimensions. */
		need_workspace = TRUE;
		transpose_it = TRUE;
		break;
	case JXFORM_ROT_90:
		if (info->trim)
			trim_right_edge(info, srcinfo->output_height);
		/* Need workspace arrays having transposed dimensions. */
		need_workspace = TRUE;
		transpose_it = TRUE;
		break;
	case JXFORM_ROT_180:
		if (info->trim) {
			trim_right_edge(info, srcinfo->output_width);
			trim_bottom_edge(info, srcinfo->output_height);
		}
		/* Need workspace arrays having same dimensions as source image. */
		need_workspace = TRUE;
		break;
	case JXFORM_ROT_270:
		if (info->trim)
			trim_bottom_edge(info, srcinfo->output_width);
		/* Need workspace arrays having transposed dimensions. */
		need_workspace = TRUE;
		transpose_it = TRUE;
		break;
	}

	/* Allocate workspace if needed.
	 * Note that we allocate arrays padded out to the next iMCU boundary,
	 * so that transform routines need not worry about missing edge blocks.
	 */
	if (need_workspace) {
		coef_arrays = (jvirt_barray_ptr *)
		    (*srcinfo->mem->alloc_small) ((j_common_ptr) srcinfo, JPOOL_IMAGE,
						  SIZEOF(jvirt_barray_ptr) * info->num_components);
		width_in_iMCUs = (JDIMENSION)
		    jdiv_round_up((long) info->output_width, (long) info->iMCU_sample_width);
		height_in_iMCUs = (JDIMENSION)
		    jdiv_round_up((long) info->output_height, (long) info->iMCU_sample_height);
		for (ci = 0; ci < info->num_components; ci++) {
			compptr = srcinfo->comp_info + ci;
			if (info->num_components == 1) {
				/* we're going to force samp factors to 1x1 in this case */
				h_samp_factor = v_samp_factor = 1;
			} else if (transpose_it) {
				h_samp_factor = compptr->v_samp_factor;
				v_samp_factor = compptr->h_samp_factor;
			} else {
				h_samp_factor = compptr->h_samp_factor;
				v_samp_factor = compptr->v_samp_factor;
			}
			width_in_blocks = width_in_iMCUs * h_samp_factor;
			height_in_blocks = height_in_iMCUs * v_samp_factor;
			coef_arrays[ci] = (*srcinfo->mem->request_virt_barray)
			    ((j_common_ptr) srcinfo, JPOOL_IMAGE, FALSE,
			     width_in_blocks, height_in_blocks, (JDIMENSION) v_samp_factor);
		}
		info->workspace_coef_arrays = coef_arrays;
	} else
		info->workspace_coef_arrays = NULL;

	return TRUE;
}


/* Transpose destination image parameters */

LOCAL(void)
    transpose_critical_parameters(j_compress_ptr dstinfo)
{
	int tblno, i, j, ci, itemp;
	jpeg_component_info *compptr;
	JQUANT_TBL *qtblptr;
	JDIMENSION jtemp;
	UINT16 qtemp;

	/* Transpose image dimensions */
	jtemp = dstinfo->image_width;
	dstinfo->image_width = dstinfo->image_height;
	dstinfo->image_height = jtemp;
	itemp = dstinfo->min_DCT_h_scaled_size;
	dstinfo->min_DCT_h_scaled_size = dstinfo->min_DCT_v_scaled_size;
	dstinfo->min_DCT_v_scaled_size = itemp;

	/* Transpose sampling factors */
	for (ci = 0; ci < dstinfo->num_components; ci++) {
		compptr = dstinfo->comp_info + ci;
		itemp = compptr->h_samp_factor;
		compptr->h_samp_factor = compptr->v_samp_factor;
		compptr->v_samp_factor = itemp;
	}

	/* Transpose quantization tables */
	for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {
		qtblptr = dstinfo->quant_tbl_ptrs[tblno];
		if (qtblptr != NULL) {
			for (i = 0; i < DCTSIZE; i++) {
				for (j = 0; j < i; j++) {
					qtemp = qtblptr->quantval[i * DCTSIZE + j];
					qtblptr->quantval[i * DCTSIZE + j] = qtblptr->quantval[j * DCTSIZE + i];
					qtblptr->quantval[j * DCTSIZE + i] = qtemp;
				}
			}
		}
	}
}


/* Adjust Exif image parameters.
 *
 * We try to adjust the Tags ExifImageWidth and ExifImageHeight if possible.
 */

LOCAL(void) adjust_exif_parameters(JOCTET FAR * data, unsigned int length, JDIMENSION new_width, JDIMENSION new_height)
{
	boolean is_motorola;	/* Flag for byte order */
	unsigned int number_of_tags, tagnum;
	unsigned int firstoffset, offset;
	JDIMENSION new_value;

	if (length < 12)
		return;		/* Length of an IFD entry */

	/* Discover byte order */
	if (GETJOCTET(data[0]) == 0x49 && GETJOCTET(data[1]) == 0x49)
		is_motorola = FALSE;
	else if (GETJOCTET(data[0]) == 0x4D && GETJOCTET(data[1]) == 0x4D)
		is_motorola = TRUE;
	else
		return;

	/* Check Tag Mark */
	if (is_motorola) {
		if (GETJOCTET(data[2]) != 0)
			return;
		if (GETJOCTET(data[3]) != 0x2A)
			return;
	} else {
		if (GETJOCTET(data[3]) != 0)
			return;
		if (GETJOCTET(data[2]) != 0x2A)
			return;
	}

	/* Get first IFD offset (offset to IFD0) */
	if (is_motorola) {
		if (GETJOCTET(data[4]) != 0)
			return;
		if (GETJOCTET(data[5]) != 0)
			return;
		firstoffset = GETJOCTET(data[6]);
		firstoffset <<= 8;
		firstoffset += GETJOCTET(data[7]);
	} else {
		if (GETJOCTET(data[7]) != 0)
			return;
		if (GETJOCTET(data[6]) != 0)
			return;
		firstoffset = GETJOCTET(data[5]);
		firstoffset <<= 8;
		firstoffset += GETJOCTET(data[4]);
	}
	if (firstoffset > length - 2)
		return;		/* check end of data segment */

	/* Get the number of directory entries contained in this IFD */
	if (is_motorola) {
		number_of_tags = GETJOCTET(data[firstoffset]);
		number_of_tags <<= 8;
		number_of_tags += GETJOCTET(data[firstoffset + 1]);
	} else {
		number_of_tags = GETJOCTET(data[firstoffset + 1]);
		number_of_tags <<= 8;
		number_of_tags += GETJOCTET(data[firstoffset]);
	}
	if (number_of_tags == 0)
		return;
	firstoffset += 2;

	/* Search for ExifSubIFD offset Tag in IFD0 */
	for (;;) {
		if (firstoffset > length - 12)
			return;	/* check end of data segment */
		/* Get Tag number */
		if (is_motorola) {
			tagnum = GETJOCTET(data[firstoffset]);
			tagnum <<= 8;
			tagnum += GETJOCTET(data[firstoffset + 1]);
		} else {
			tagnum = GETJOCTET(data[firstoffset + 1]);
			tagnum <<= 8;
			tagnum += GETJOCTET(data[firstoffset]);
		}
		if (tagnum == 0x8769)
			break;	/* found ExifSubIFD offset Tag */
		if (--number_of_tags == 0)
			return;
		firstoffset += 12;
	}

	/* Get the ExifSubIFD offset */
	if (is_motorola) {
		if (GETJOCTET(data[firstoffset + 8]) != 0)
			return;
		if (GETJOCTET(data[firstoffset + 9]) != 0)
			return;
		offset = GETJOCTET(data[firstoffset + 10]);
		offset <<= 8;
		offset += GETJOCTET(data[firstoffset + 11]);
	} else {
		if (GETJOCTET(data[firstoffset + 11]) != 0)
			return;
		if (GETJOCTET(data[firstoffset + 10]) != 0)
			return;
		offset = GETJOCTET(data[firstoffset + 9]);
		offset <<= 8;
		offset += GETJOCTET(data[firstoffset + 8]);
	}
	if (offset > length - 2)
		return;		/* check end of data segment */

	/* Get the number of directory entries contained in this SubIFD */
	if (is_motorola) {
		number_of_tags = GETJOCTET(data[offset]);
		number_of_tags <<= 8;
		number_of_tags += GETJOCTET(data[offset + 1]);
	} else {
		number_of_tags = GETJOCTET(data[offset + 1]);
		number_of_tags <<= 8;
		number_of_tags += GETJOCTET(data[offset]);
	}
	if (number_of_tags < 2)
		return;
	offset += 2;

	/* Search for ExifImageWidth and ExifImageHeight Tags in this SubIFD */
	do {
		if (offset > length - 12)
			return;	/* check end of data segment */
		/* Get Tag number */
		if (is_motorola) {
			tagnum = GETJOCTET(data[offset]);
			tagnum <<= 8;
			tagnum += GETJOCTET(data[offset + 1]);
		} else {
			tagnum = GETJOCTET(data[offset + 1]);
			tagnum <<= 8;
			tagnum += GETJOCTET(data[offset]);
		}
		if (tagnum == 0xA002 || tagnum == 0xA003) {
			if (tagnum == 0xA002)
				new_value = new_width;	/* ExifImageWidth Tag */
			else
				new_value = new_height;	/* ExifImageHeight Tag */
			if (is_motorola) {
				data[offset + 2] = 0;	/* Format = unsigned long (4 octets) */
				data[offset + 3] = 4;
				data[offset + 4] = 0;	/* Number Of Components = 1 */
				data[offset + 5] = 0;
				data[offset + 6] = 0;
				data[offset + 7] = 1;
				data[offset + 8] = 0;
				data[offset + 9] = 0;
				data[offset + 10] = (JOCTET) ((new_value >> 8) & 0xFF);
				data[offset + 11] = (JOCTET) (new_value & 0xFF);
			} else {
				data[offset + 2] = 4;	/* Format = unsigned long (4 octets) */
				data[offset + 3] = 0;
				data[offset + 4] = 1;	/* Number Of Components = 1 */
				data[offset + 5] = 0;
				data[offset + 6] = 0;
				data[offset + 7] = 0;
				data[offset + 8] = (JOCTET) (new_value & 0xFF);
				data[offset + 9] = (JOCTET) ((new_value >> 8) & 0xFF);
				data[offset + 10] = 0;
				data[offset + 11] = 0;
			}
		}
		offset += 12;
	} while (--number_of_tags);
}


/* Adjust output image parameters as needed.
 *
 * This must be called after jpeg_copy_critical_parameters()
 * and before jpeg_write_coefficients().
 *
 * The return value is the set of virtual coefficient arrays to be written
 * (either the ones allocated by jtransform_request_workspace, or the
 * original source data arrays).  The caller will need to pass this value
 * to jpeg_write_coefficients().
 */

GLOBAL(jvirt_barray_ptr *)
    jtransform_adjust_parameters(j_decompress_ptr srcinfo,
			     j_compress_ptr dstinfo, jvirt_barray_ptr * src_coef_arrays, jpeg_transform_info * info)
{
	/* If force-to-grayscale is requested, adjust destination parameters */
	if (info->force_grayscale) {
		/* First, ensure we have YCbCr or grayscale data, and that the source's
		 * Y channel is full resolution.  (No reasonable person would make Y
		 * be less than full resolution, so actually coping with that case
		 * isn't worth extra code space.  But we check it to avoid crashing.)
		 */
		if (((dstinfo->jpeg_color_space == JCS_YCbCr &&
		      dstinfo->num_components == 3) ||
		     (dstinfo->jpeg_color_space == JCS_GRAYSCALE &&
		      dstinfo->num_components == 1)) &&
		    srcinfo->comp_info[0].h_samp_factor == srcinfo->max_h_samp_factor &&
		    srcinfo->comp_info[0].v_samp_factor == srcinfo->max_v_samp_factor) {
			/* We use jpeg_set_colorspace to make sure subsidiary settings get fixed
			 * properly.  Among other things, it sets the target h_samp_factor &
			 * v_samp_factor to 1, which typically won't match the source.
			 * We have to preserve the source's quantization table number, however.
			 */
			int sv_quant_tbl_no = dstinfo->comp_info[0].quant_tbl_no;
			jpeg_set_colorspace(dstinfo, JCS_GRAYSCALE);
			dstinfo->comp_info[0].quant_tbl_no = sv_quant_tbl_no;
		} else {
			/* Sorry, can't do it */
			ERREXIT(dstinfo, JERR_CONVERSION_NOTIMPL);
		}
	} else if (info->num_components == 1) {
		/* For a single-component source, we force the destination sampling factors
		 * to 1x1, with or without force_grayscale.  This is useful because some
		 * decoders choke on grayscale images with other sampling factors.
		 */
		dstinfo->comp_info[0].h_samp_factor = 1;
		dstinfo->comp_info[0].v_samp_factor = 1;
	}

	/* Correct the destination's image dimensions as necessary
	 * for rotate/flip, resize, and crop operations.
	 */
	dstinfo->jpeg_width = info->output_width;
	dstinfo->jpeg_height = info->output_height;

	/* Transpose destination image parameters */
	switch (info->transform) {
	case JXFORM_TRANSPOSE:
	case JXFORM_TRANSVERSE:
	case JXFORM_ROT_90:
	case JXFORM_ROT_270:
		transpose_critical_parameters(dstinfo);
		break;
	default:
		break;
	}

	/* Adjust Exif properties */
	if (srcinfo->marker_list != NULL &&
	    srcinfo->marker_list->marker == JPEG_APP0 + 1 &&
	    srcinfo->marker_list->data_length >= 6 &&
	    GETJOCTET(srcinfo->marker_list->data[0]) == 0x45 &&
	    GETJOCTET(srcinfo->marker_list->data[1]) == 0x78 &&
	    GETJOCTET(srcinfo->marker_list->data[2]) == 0x69 &&
	    GETJOCTET(srcinfo->marker_list->data[3]) == 0x66 &&
	    GETJOCTET(srcinfo->marker_list->data[4]) == 0 && GETJOCTET(srcinfo->marker_list->data[5]) == 0) {
		/* Suppress output of JFIF marker */
		dstinfo->write_JFIF_header = FALSE;
		/* Adjust Exif image parameters */
		if (dstinfo->jpeg_width != srcinfo->image_width || dstinfo->jpeg_height != srcinfo->image_height)
			/* Align data segment to start of TIFF structure for parsing */
			adjust_exif_parameters(srcinfo->marker_list->data + 6,
					       srcinfo->marker_list->data_length - 6,
					       dstinfo->jpeg_width, dstinfo->jpeg_height);
	}

	/* Return the appropriate output data set */
	if (info->workspace_coef_arrays != NULL)
		return info->workspace_coef_arrays;
	return src_coef_arrays;
}


/* Execute the actual transformation, if any.
 *
 * This must be called *after* jpeg_write_coefficients, because it depends
 * on jpeg_write_coefficients to have computed subsidiary values such as
 * the per-component width and height fields in the destination object.
 *
 * Note that some transformations will modify the source data arrays!
 */

GLOBAL(void)
    jtransform_execute_transform(j_decompress_ptr srcinfo,
			     j_compress_ptr dstinfo, jvirt_barray_ptr * src_coef_arrays, jpeg_transform_info * info)
{
	jvirt_barray_ptr *dst_coef_arrays = info->workspace_coef_arrays;

	/* Note: conditions tested here should match those in switch statement
	 * in jtransform_request_workspace()
	 */
	switch (info->transform) {
	case JXFORM_NONE:
		break;
	case JXFORM_FLIP_H:
		do_flip_h_no_crop(srcinfo, dstinfo, 0, src_coef_arrays);
		break;
	case JXFORM_FLIP_V:
		do_flip_v(srcinfo, dstinfo, 0, 0, src_coef_arrays, dst_coef_arrays);
		break;
	case JXFORM_TRANSPOSE:
		do_transpose(srcinfo, dstinfo, 0, 0,
			     src_coef_arrays, dst_coef_arrays);
		break;
	case JXFORM_TRANSVERSE:
		do_transverse(srcinfo, dstinfo, 0, 0, src_coef_arrays, dst_coef_arrays);
		break;
	case JXFORM_ROT_90:
		do_rot_90(srcinfo, dstinfo, 0, 0, src_coef_arrays, dst_coef_arrays);
		break;
	case JXFORM_ROT_180:
		do_rot_180(srcinfo, dstinfo, 0, 0, src_coef_arrays, dst_coef_arrays);
		break;
	case JXFORM_ROT_270:
		do_rot_270(srcinfo, dstinfo, 0, 0, src_coef_arrays, dst_coef_arrays);
		break;
	}
}

#endif				/* TRANSFORMS_SUPPORTED */


/* Setup decompression object to save desired markers in memory.
 * This must be called before jpeg_read_header() to have the desired effect.
 */

GLOBAL(void)
    jcopy_markers_setup(j_decompress_ptr srcinfo, JCOPY_OPTION option)
{
#ifdef SAVE_MARKERS_SUPPORTED
	int m;

	/* Save comments except under NONE option */
	if (option != JCOPYOPT_NONE) {
		jpeg_save_markers(srcinfo, JPEG_COM, 0xFFFF);
	}
	/* Save all types of APPn markers iff ALL option */
	if (option == JCOPYOPT_ALL) {
		for (m = 0; m < 16; m++)
			jpeg_save_markers(srcinfo, JPEG_APP0 + m, 0xFFFF);
	}
#endif				/* SAVE_MARKERS_SUPPORTED */
}

/* Copy markers saved in the given source object to the destination object.
 * This should be called just after jpeg_start_compress() or
 * jpeg_write_coefficients().
 * Note that those routines will have written the SOI, and also the
 * JFIF APP0 or Adobe APP14 markers if selected.
 */

GLOBAL(void) jcopy_markers_execute(j_decompress_ptr srcinfo, j_compress_ptr dstinfo, JCOPY_OPTION option)
{
	jpeg_saved_marker_ptr marker;

	/* In the current implementation, we don't actually need to examine the
	 * option flag here; we just copy everything that got saved.
	 * But to avoid confusion, we do not output JFIF and Adobe APP14 markers
	 * if the encoder library already wrote one.
	 */
	for (marker = srcinfo->marker_list; marker != NULL; marker = marker->next) {
		if (dstinfo->write_JFIF_header &&
		    marker->marker == JPEG_APP0 &&
		    marker->data_length >= 5 &&
		    GETJOCTET(marker->data[0]) == 0x4A &&
		    GETJOCTET(marker->data[1]) == 0x46 &&
		    GETJOCTET(marker->data[2]) == 0x49 &&
		    GETJOCTET(marker->data[3]) == 0x46 && GETJOCTET(marker->data[4]) == 0)
			continue;	/* reject duplicate JFIF */
		if (dstinfo->write_Adobe_marker &&
		    marker->marker == JPEG_APP0 + 14 &&
		    marker->data_length >= 5 &&
		    GETJOCTET(marker->data[0]) == 0x41 &&
		    GETJOCTET(marker->data[1]) == 0x64 &&
		    GETJOCTET(marker->data[2]) == 0x6F &&
		    GETJOCTET(marker->data[3]) == 0x62 && GETJOCTET(marker->data[4]) == 0x65)
			continue;	/* reject duplicate Adobe */
#ifdef NEED_FAR_POINTERS
		/* We could use jpeg_write_marker if the data weren't FAR... */
		{
			unsigned int i;
			jpeg_write_m_header(dstinfo, marker->marker, marker->data_length);
			for (i = 0; i < marker->data_length; i++)
				jpeg_write_m_byte(dstinfo, marker->data[i]);
		}
#else
		jpeg_write_marker(dstinfo, marker->marker, marker->data, marker->data_length);
#endif
	}
}