/*
 *
 *   Softweave calculator for Gutenprint.
 *
 *   Copyright 2000 Charles Briscoe-Smith <cpbs@debian.org>
 *
 *   This program is free software; you can redistribute it and/or modify it
 *   under the terms of the GNU General Public License as published by the Free
 *   Software Foundation; either version 2 of the License, or (at your option)
 *   any later version.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 *   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 *   for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

/*
 * This file must include only standard C header files.  The core code must
 * compile on generic platforms that don't support glib, gimp, gtk, etc.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <string.h>
#include <gutenprint/gutenprint.h>
#include "gutenprint-internal.h"
#include <gutenprint/gutenprint-intl-internal.h>
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif

static int
gcd(int x, int y)
{
	if (y == 0)
		return x;
	while (x != 0) {
		if (y > x) {
			int t = x;
			x = y;
			y = t;
		}
		x %= y;
	}
	return y;
}

typedef struct stpi_softweave
{
  stp_linebufs_t *linebases;	/* Base address of each row buffer */
  stp_lineoff_t *lineoffsets;	/* Offsets within each row buffer */
  stp_lineactive_t *lineactive;	/* Does this line have anything printed? */
  stp_linecount_t *linecounts;	/* How many rows we've printed this pass */
  stp_linebounds_t *linebounds;	/* Starting and ending print column */
  stp_pass_t *passes;		/* Circular list of pass numbers */
  int last_pass_offset;		/* Starting row (offset from the start of */
				/* the page) of the most recently printed */
				/* pass (so we can determine how far to */
				/* advance the paper) */
  int last_pass;		/* Number of the most recently printed pass */

  int jets;			/* Number of jets per color */
  int virtual_jets;		/* Number of jets per color, taking into */
				/* account the head offset */
  int separation;		/* Offset from one jet to the next in rows */
  void *weaveparm;		/* Weave calculation parameter block */

  int horizontal_weave;		/* Number of horizontal passes required */
				/* This is > 1 for some of the ultra-high */
				/* resolution modes */
  int vertical_subpasses;	/* Number of passes per line (for better */
				/* quality) */
  int vmod;			/* Number of banks of passes */
  int oversample;		/* Excess precision per row */
  int repeat_count;		/* How many times a pass is repeated */
  int ncolors;			/* How many colors */
  int linewidth;		/* Line width in input pixels */
  int vertical_height;		/* Image height in output pixels */
  int firstline;		/* Actual first line (referenced to paper) */

  int bitwidth;			/* Bits per pixel */
  int lineno;
  int vertical_oversample;	/* Vertical oversampling */
  int current_vertical_subpass;
  int horizontal_width;		/* Horizontal width, in bits */
  int *head_offset;		/* offset of printheads */
  unsigned char *s[STP_MAX_WEAVE];
  unsigned char *fold_buf;
  unsigned char *comp_buf;
  stp_weave_t wcache;
  int rcache;
  int vcache;
  stp_flushfunc *flushfunc;
  stp_fillfunc *fillfunc;
  stp_packfunc *pack;
  stp_compute_linewidth_func *compute_linewidth;
} stpi_softweave_t;

/* RAW WEAVE */

typedef struct raw {
	int separation;
	int jets;
	int oversampling;
	int advancebasis;
	int subblocksperpassblock;
	int passespersubblock;
	stp_weave_strategy_t strategy;
	stp_vars_t *v;
} raw_t;

/*
 * Strategy types currently defined:
 *
 *  0: zig-zag type pass block filling
 *  1: ascending pass block filling
 *  2: descending pass block filling
 *  3: ascending fill with 2x expansion
 *  4: staggered zig-zag neighbour-avoidance fill
 *  5: ascending fill with 3x expansion
 *
 * In theory, strategy 0 should be optimal; in practice, it can lead
 * to visible areas of banding.  If it's necessary to avoid filling
 * neighbouring rows in neighbouring passes, strategy 4 should be optimal,
 * at least for some weaves.
 */

static void
initialize_raw_weave(raw_t *w,	/* I - weave struct to be filled in */
                     int separation,	/* I - jet separation */
                     int jets,	/* I - number of jets */
                     int oversample,	/* I - oversampling factor */
                     stp_weave_strategy_t strat,	/* I - weave pattern variation to use */
		     stp_vars_t *v)
{
	w->separation = separation;
	w->jets = jets;
	w->oversampling = oversample;
	w->advancebasis = jets / oversample;
	if (w->advancebasis == 0)
	  w->advancebasis++;
	w->subblocksperpassblock = gcd(separation, w->advancebasis);
	w->passespersubblock = separation / w->subblocksperpassblock;
	w->strategy = strat;
	w->v = v;
}

static void
calculate_raw_pass_parameters(raw_t *w,		/* I - weave parameters */
                              int pass,		/* I - pass number ( >= 0) */
                              int *startrow,	/* O - print head position */
                              int *subpass)	/* O - subpass number */
{
	int band, passinband, subpassblock, subpassoffset;

	band = pass / (w->separation * w->oversampling);
	passinband = pass % (w->separation * w->oversampling);
	subpassblock = pass % w->separation
	                 * w->subblocksperpassblock / w->separation;

	switch (w->strategy) {
	case STP_WEAVE_ZIGZAG:
		if (subpassblock * 2 < w->subblocksperpassblock)
			subpassoffset = 2 * subpassblock;
		else
			subpassoffset = 2 * (w->subblocksperpassblock
			                      - subpassblock) - 1;
		break;
	case STP_WEAVE_ASCENDING:
		subpassoffset = subpassblock;
		break;
	case STP_WEAVE_DESCENDING:
		subpassoffset = w->subblocksperpassblock - 1 - subpassblock;
		break;
	case STP_WEAVE_ASCENDING_2X:
		if (subpassblock * 2 < w->subblocksperpassblock)
			subpassoffset = 2 * subpassblock;
		else
			subpassoffset = 1 + 2 * (subpassblock
			                          - (w->subblocksperpassblock
			                              + 1) / 2);
		break;
	case STP_WEAVE_ASCENDING_3X:
		if (subpassblock * 3 < w->subblocksperpassblock)
			subpassoffset = 3 * subpassblock;
		else if (3 * (subpassblock - (w->subblocksperpassblock + 2) / 3)
		          < w->subblocksperpassblock - 2)
			subpassoffset = 2 + 3 * (subpassblock
			                          - (w->subblocksperpassblock
			                              + 2) / 3);
		else
			subpassoffset = 1 + 3 * (subpassblock
			                          - (w->subblocksperpassblock
			                              + 2) / 3
						  - w->subblocksperpassblock
						      / 3);
		break;
	case STP_WEAVE_STAGGERED:
		if (subpassblock * 2 < w->subblocksperpassblock)
			subpassoffset = 2 * subpassblock;
		else if (subpassblock * 2 < w->subblocksperpassblock + 2)
			subpassoffset = 1;
		else
			subpassoffset = 2 * (w->subblocksperpassblock
			                      - subpassblock) + 1;
		break;
	default:
		subpassoffset = subpassblock;
		break;
	}

	*startrow = w->separation * w->jets * band
	              + w->advancebasis * passinband + subpassoffset;
	*subpass = passinband / w->separation;
}

static void
calculate_raw_row_parameters(raw_t *w,		/* I - weave parameters */
                             int row,		/* I - row number */
                             int subpass,	/* I - subpass number */
                             int *pass,		/* O - pass number */
                             int *jet,		/* O - jet number in pass */
                             int *startrow)	/* O - starting row of pass */
{
	int subblockoffset, subpassblock, band, baserow, passinband, offset;
	int pass_div_separation;
	int pass_mod_separation;
	int off_mod_separation;

	subblockoffset = row % w->subblocksperpassblock;
	switch (w->strategy) {
	case STP_WEAVE_ZIGZAG:
		if (subblockoffset % 2 == 0)
			subpassblock = subblockoffset / 2;
		else
			subpassblock = w->subblocksperpassblock
			                 - (subblockoffset + 1) / 2;
		break;
	case STP_WEAVE_ASCENDING:
		subpassblock = subblockoffset;
		break;
	case STP_WEAVE_DESCENDING:
		subpassblock = w->subblocksperpassblock - 1 - subblockoffset;
		break;
	case STP_WEAVE_ASCENDING_2X:
		if (subblockoffset % 2 == 0)
			subpassblock = subblockoffset / 2;
		else
			subpassblock = (subblockoffset - 1) / 2
			               + (w->subblocksperpassblock + 1) / 2;
		break;
	case STP_WEAVE_ASCENDING_3X:
		if (subblockoffset % 3 == 0)
			subpassblock = subblockoffset / 3;
		else if (subblockoffset % 3 == 1)
			subpassblock = (subblockoffset - 1) / 3
			                 + (w->subblocksperpassblock + 2) / 3;
		else
			subpassblock = (subblockoffset - 2) / 3
			                 + (w->subblocksperpassblock + 2) / 3
			                 + (w->subblocksperpassblock + 1) / 3;
		break;
	case STP_WEAVE_STAGGERED:
		if (subblockoffset % 2 == 0)
			subpassblock = subblockoffset / 2;
		else if (subblockoffset == 1)
			subpassblock = (w->subblocksperpassblock + 1) / 2;
		else
			subpassblock = w->subblocksperpassblock
			                 - (subblockoffset - 1) / 2;
		break;
	default:
		subpassblock = subblockoffset;
		break;
	}

	band = row / (w->separation * w->jets);
	baserow = row - subblockoffset - band * w->separation * w->jets;
	passinband = baserow / w->advancebasis;
	offset = baserow % w->advancebasis;
	pass_div_separation = passinband / w->separation;
	pass_mod_separation = passinband % w->separation;
	off_mod_separation = offset % w->separation;

	while (off_mod_separation != 0
	       || pass_div_separation != subpass
	       || pass_mod_separation / w->passespersubblock
	            != subpassblock)
	  {
	    offset += w->advancebasis;
	    passinband--;
	    if (passinband >= 0)
	      {
		pass_mod_separation--;
		if (pass_mod_separation < 0)
		  {
		    pass_mod_separation += w->separation;
		    pass_div_separation--;
		  }
		if (w->advancebasis < w->separation)
		  {
		    off_mod_separation += w->advancebasis;
		    if (off_mod_separation >= w->separation)
		      off_mod_separation -= w->separation;
		  }
		else if (w->advancebasis > w->separation)
		  off_mod_separation = offset % w->separation;
	      }
	    else
	      {
		const int roundedjets =
		  (w->advancebasis * w->oversampling) % w->jets;
		band--;
		passinband += w->separation * w->oversampling;
		offset += w->separation * (w->jets - roundedjets);
		pass_div_separation = passinband / w->separation;
		pass_mod_separation = passinband % w->separation;
		off_mod_separation = offset % w->separation;
	      }
	  }

	*pass = band * w->oversampling * w->separation + passinband;
	*jet = (offset / w->separation) % w->jets;
	*startrow = row - (*jet * w->separation);
}

/* COOKED WEAVE */

typedef struct cooked {
	raw_t rw;
	int first_row_printed;
	int last_row_printed;

	int first_premapped_pass;	/* First raw pass used by this page */
	int first_normal_pass;
	int first_postmapped_pass;
	int first_unused_pass;

	int *pass_premap;
	int *stagger_premap;
	int *pass_postmap;
	int *stagger_postmap;
} cooked_t;

typedef struct startmap {
  int startrow;
  int map;
  int pos;			/* Secondary key for stable sort */
} startmap_t;

static int
smap_compare(const void *p1, const void *p2)
{
  const startmap_t *s1 = (const startmap_t *)p1;
  const startmap_t *s2 = (const startmap_t *)p2;
  if (s1->startrow < s2->startrow)
    return -1;
  else if (s1->startrow > s2->startrow)
    return 1;
  else if (s1->pos < s2->pos)
    return -1;
  else
    return 1;
}

static void
sort_by_start_row(int *map, int *startrows, int count)
{
  startmap_t *smap = stp_malloc(sizeof(startmap_t) * count);
  int i;
  for (i = 0; i < count; i++)
    {
      smap[i].startrow = startrows[i];
      smap[i].map = map[i];
      smap[i].pos = i;
    }
  qsort(smap, count, sizeof(startmap_t), smap_compare);
  for (i = 0; i < count; i++)
    {
      startrows[i] = smap[i].startrow;
      map[i] = smap[i].map;
    }
  stp_free(smap);
}

static void
calculate_stagger(raw_t *w, int *map, int *startrows_stagger, int count)
{
	int i;

	for (i = 0; i < count; i++) {
		int startrow, subpass;
		calculate_raw_pass_parameters(w, map[i], &startrow, &subpass);
		startrow -= w->separation * w->jets;
		startrows_stagger[i] = (startrows_stagger[i] - startrow)
		                         / w->separation;
	}
}

static void
invert_map(int *map, int *stagger, int count, int oldfirstpass,
           int newfirstpass)
{
	int i;
	int *newmap, *newstagger;
	newmap = stp_malloc(count * sizeof(int));
	newstagger = stp_malloc(count * sizeof(int));

	for (i = 0; i < count; i++) {
		newmap[map[i] - oldfirstpass] = i + newfirstpass;
		newstagger[map[i] - oldfirstpass] = stagger[i];
	}

	memcpy(map, newmap, count * sizeof(int));
	memcpy(stagger, newstagger, count * sizeof(int));
	stp_free(newstagger);
	stp_free(newmap);
}

static void
make_passmap(raw_t *w, int **map, int **starts, int first_pass_number,
             int first_pass_to_map, int first_pass_after_map,
             int first_pass_to_stagger, int first_pass_after_stagger,
             int first_row_of_maximal_pass, int separations_to_distribute)
{
	int *passmap, *startrows;
	int passes_to_map = first_pass_after_map - first_pass_to_map;
	int i;

	STPI_ASSERT(first_pass_to_map <= first_pass_after_map, w->v);
	STPI_ASSERT(first_pass_to_stagger <= first_pass_after_stagger, w->v);

	*map = passmap = stp_malloc(passes_to_map * sizeof(int));
	*starts = startrows = stp_malloc(passes_to_map * sizeof(int));

	for (i = 0; i < passes_to_map; i++) {
		int startrow, subpass;
		int pass = i + first_pass_to_map;
		calculate_raw_pass_parameters(w, pass, &startrow, &subpass);
		passmap[i] = pass;
		if (first_row_of_maximal_pass >= 0)
			startrow = first_row_of_maximal_pass - startrow
			             + w->separation * w->jets;
		else
			startrow -= w->separation * w->jets;
		while (startrow < 0)
			startrow += w->separation;
		startrows[i] = startrow;
	}

	sort_by_start_row(passmap, startrows, passes_to_map);

	separations_to_distribute++;

	for (i = 0; i < first_pass_after_stagger - first_pass_to_stagger; i++) {
		int offset = first_pass_to_stagger - first_pass_to_map;
		if (startrows[i + offset] / w->separation
		      < i % separations_to_distribute)
		{
			startrows[i + offset]
			  = startrows[i + offset] % w->separation
			     + w->separation * (i % separations_to_distribute);
		}
	}

	if (first_row_of_maximal_pass >= 0) {
		for (i = 0; i < passes_to_map; i++) {
			startrows[i] = first_row_of_maximal_pass - startrows[i];
		}
	}

	sort_by_start_row(passmap, startrows, passes_to_map);
	calculate_stagger(w, passmap, startrows, passes_to_map);

	invert_map(passmap, startrows, passes_to_map, first_pass_to_map,
		   first_pass_to_map - first_pass_number);
}

static void
calculate_pass_map(stp_vars_t *v,
		   cooked_t *w,		/* I - weave parameters */
                   int pageheight,	/* I - number of rows on page */
                   int firstrow,	/* I - first printed row */
                   int lastrow)		/* I - last printed row */
{
	int startrow, subpass;
	int pass = -1;

	w->first_row_printed = firstrow;
	w->last_row_printed = lastrow;

	if (pageheight <= lastrow)
		pageheight = lastrow + 1;

	do {
		calculate_raw_pass_parameters(&w->rw, ++pass,
		                              &startrow, &subpass);
	} while (startrow - w->rw.separation < firstrow);

	w->first_premapped_pass = pass;

	while (startrow < w->rw.separation * w->rw.jets
	       && startrow - w->rw.separation < pageheight
	       && startrow <= lastrow + w->rw.separation * w->rw.jets)
	{
		calculate_raw_pass_parameters(&w->rw, ++pass,
		                              &startrow, &subpass);
	}
	w->first_normal_pass = pass;

	while (startrow - w->rw.separation < pageheight
	       && startrow <= lastrow + w->rw.separation * w->rw.jets)
	{
		calculate_raw_pass_parameters(&w->rw, ++pass,
		                              &startrow, &subpass);
	}
	w->first_postmapped_pass = pass;

	while (startrow <= lastrow + w->rw.separation * w->rw.jets) {
		calculate_raw_pass_parameters(&w->rw, ++pass,
		                              &startrow, &subpass);
	}
	w->first_unused_pass = pass;

	stp_dprintf(STP_DBG_WEAVE_PARAMS, v,
		    "first premapped %d first normal %d first postmapped %d "
		    "first unused %d\n",
		    w->first_premapped_pass, w->first_normal_pass,
		    w->first_postmapped_pass, w->first_unused_pass);
	/*
	 * FIXME: make sure first_normal_pass doesn't advance beyond
	 * first_postmapped_pass, or first_postmapped_pass doesn't
	 * retreat before first_normal_pass.
	 */

	if (w->first_normal_pass > w->first_premapped_pass) {
		int spread, separations_to_distribute, normal_passes_mapped;
		separations_to_distribute = firstrow / w->rw.separation;
		spread = (separations_to_distribute + 1) * w->rw.separation;
		normal_passes_mapped = (spread + w->rw.advancebasis - 1)
		                            / w->rw.advancebasis;
		w->first_normal_pass += normal_passes_mapped;
		make_passmap(&w->rw, &w->pass_premap, &w->stagger_premap,
		             w->first_premapped_pass,
		             w->first_premapped_pass, w->first_normal_pass,
			     w->first_premapped_pass,
			     w->first_normal_pass - normal_passes_mapped,
		             -1, separations_to_distribute);
	} else {
		w->pass_premap = 0;
		w->stagger_premap = 0;
	}

	if (w->first_unused_pass >= w->first_postmapped_pass) {
		int spread, separations_to_distribute, normal_passes_mapped;
		separations_to_distribute = (pageheight - lastrow - 1)
		                                     / w->rw.separation;
		spread = (separations_to_distribute + 1) * w->rw.separation;
		normal_passes_mapped = (spread + w->rw.advancebasis)
		                             / w->rw.advancebasis;
		w->first_postmapped_pass -= normal_passes_mapped;
		make_passmap(&w->rw, &w->pass_postmap, &w->stagger_postmap,
		             w->first_premapped_pass,
		             w->first_postmapped_pass, w->first_unused_pass,
			     w->first_postmapped_pass + normal_passes_mapped,
			     w->first_unused_pass,
		             pageheight - 1
		                 - w->rw.separation * (w->rw.jets - 1),
			     separations_to_distribute);
	} else {
		w->pass_postmap = 0;
		w->stagger_postmap = 0;
	}
}

static void *				/* O - weave parameter block */
initialize_weave_params(int separation,		/* I - jet separation */
                        int jets,		/* I - number of jets */
                        int oversample,		/* I - oversampling factor */
                        int firstrow,	/* I - first row number to print */
                        int lastrow,	/* I - last row number to print */
                        int pageheight,	/* I - number of rows on the whole
                        		       page, without using any
                        		       expanded margin facilities */
                        stp_weave_strategy_t strategy,	/* I - weave pattern variant to use */
			stp_vars_t *v)
{
	cooked_t *w = stp_malloc(sizeof(cooked_t));
	if (w) {
		initialize_raw_weave(&w->rw, separation, jets, oversample, strategy, v);
		calculate_pass_map(v, w, pageheight, firstrow, lastrow);
	}
	return w;
}

static void
stpi_destroy_weave_params(void *vw)
{
	cooked_t *w = (cooked_t *) vw;

	if (w->pass_premap) stp_free(w->pass_premap);
	if (w->stagger_premap) stp_free(w->stagger_premap);
	if (w->pass_postmap) stp_free(w->pass_postmap);
	if (w->stagger_postmap) stp_free(w->stagger_postmap);
	stp_free(w);
}

static void
stpi_calculate_row_parameters(void *vw,		/* I - weave parameters */
			      int row,		/* I - row number */
			      int subpass,	/* I - subpass */
			      int *pass,	/* O - pass containing row */
			      int *jetnum,	/* O - jet number of row */
			      int *startingrow,	/* O - phys start of pass */
			      int *ophantomrows, /* O - missing rows @ start */
			      int *ojetsused)	/* O - jets used by pass */
{
	cooked_t *w = (cooked_t *) vw;
	int raw_pass, jet, startrow, phantomrows, jetsused;
	int stagger = 0;
	int extra;

	STPI_ASSERT(row >= w->first_row_printed, w->rw.v);
	STPI_ASSERT(row <= w->last_row_printed, w->rw.v);
	calculate_raw_row_parameters(&w->rw,
	                             row + w->rw.separation * w->rw.jets,
	                             subpass, &raw_pass, &jet, &startrow);
	startrow -= w->rw.separation * w->rw.jets;
	jetsused = w->rw.jets;
	phantomrows = 0;

	if (raw_pass < w->first_normal_pass) {
	        STPI_ASSERT(raw_pass >= w->first_premapped_pass, w->rw.v);
		*pass = w->pass_premap[raw_pass - w->first_premapped_pass];
		stagger = w->stagger_premap[raw_pass - w->first_premapped_pass];
	} else if (raw_pass >= w->first_postmapped_pass) {
	        STPI_ASSERT(raw_pass >= w->first_postmapped_pass, w->rw.v);
		*pass = w->pass_postmap[raw_pass - w->first_postmapped_pass];
		stagger = w->stagger_postmap[raw_pass
		                             - w->first_postmapped_pass];
	} else {
		*pass = raw_pass - w->first_premapped_pass;
	}

	startrow += stagger * w->rw.separation;
	*jetnum = jet - stagger;
	if (stagger < 0) {
		stagger = -stagger;
		phantomrows += stagger;
	}
	jetsused -= stagger;

	extra = w->first_row_printed
	             - (startrow + w->rw.separation * phantomrows);
	if (extra > 0) {
		extra = (extra + w->rw.separation - 1) / w->rw.separation;
		jetsused -= extra;
		phantomrows += extra;
	}

	extra = startrow + w->rw.separation * (phantomrows + jetsused - 1)
	          - w->last_row_printed;
	if (extra > 0) {
		extra = (extra + w->rw.separation - 1) / w->rw.separation;
		jetsused -= extra;
	}

	*startingrow = startrow;
	*ophantomrows = phantomrows;
	*ojetsused = jetsused;
}

/*
 * "Soft" weave
 *
 * The Epson Stylus Color/Photo printers don't have memory to print
 * using all of the nozzles in the print head.  For example, the Stylus Photo
 * 700/EX has 32 nozzles.  At 720 dpi, with an 8" wide image, a single line
 * requires (8 * 720 * 6 / 8) bytes, or 4320 bytes (because the Stylus Photo
 * printers have 6 ink colors).  To use 32 nozzles would require 138240 bytes.
 * It's actually worse than that, though, because the nozzles are spaced 8
 * rows apart.  Therefore, in order to store enough data to permit sending the
 * page as a simple raster, the printer would require enough memory to store
 * 256 rows, or 1105920 bytes.  Considering that the Photo EX can print
 * 11" wide, we're looking at more like 1.5 MB.  In fact, these printers are
 * capable of 1440 dpi horizontal resolution.  This would require 3 MB.  The
 * printers actually have 64K-256K.
 *
 * With the newer (740/750 and later) printers it's even worse, since these
 * printers support multiple dot sizes.  But that's neither here nor there.
 *
 * Older Epson printers had a mode called MicroWeave (tm).  In this mode, the
 * host fed the printer individual rows of dots, and the printer bundled them
 * up and sent them to the print head in the correct order to achieve high
 * quality.  This MicroWeave mode still works in new printers, but the
 * implementation is very minimal: the printer uses exactly one nozzle of
 * each color (the first one).  This makes printing extremely slow (more than
 * 30 minutes for one 8.5x11" page), although the quality is extremely high
 * with no visible banding whatsoever.  It's not good for the print head,
 * though, since no ink is flowing through the other nozzles.  This leads to
 * drying of ink and possible permanent damage to the print head.
 *
 * By the way, although the Epson manual says that microweave mode should be
 * used at 720 dpi, 360 dpi continues to work in much the same way.  At 360
 * dpi, data is fed to the printer one row at a time on all Epson printers.
 * The pattern that the printer uses to print is very prone to banding.
 * However, 360 dpi is inherently a low quality mode; if you're using it,
 * presumably you don't much care about quality.
 *
 * Printers from roughly the Stylus Color 600 and later do not have the
 * capability to do MicroWeave correctly.  Instead, the host must arrange
 * the output in the order that it will be sent to the print head.  This
 * is a very complex process; the jets in the print head are spaced more
 * than one row (1/720") apart, so we can't simply send consecutive rows
 * of dots to the printer.  Instead, we have to pass e. g. the first, ninth,
 * 17th, 25th... rows in order for them to print in the correct position on
 * the paper.  This interleaving process is called "soft" weaving.
 *
 * This decision was probably made to save money on memory in the printer.
 * It certainly makes the driver code far more complicated than it would
 * be if the printer could arrange the output.  Is that a bad thing?
 * Usually this takes far less CPU time than the dithering process, and it
 * does allow us more control over the printing process, e. g. to reduce
 * banding.  Conceivably, we could even use this ability to map out bad
 * jets.
 *
 * Interestingly, apparently the Windows (and presumably Macintosh) drivers
 * for most or all Epson printers still list a "microweave" mode.
 * Experiments have demonstrated that this does not in fact use the
 * "microweave" mode of the printer.  Possibly it does nothing, or it uses
 * a different weave pattern from what the non-"microweave" mode does.
 * This is unnecessarily confusing.
 *
 * What makes this interesting is that there are many different ways of
 * of accomplishing this goal.  The naive way would be to divide the image
 * up into groups of 256 rows, and print all the mod8=0 rows in the first pass,
 * mod8=1 rows in the second, and so forth.  The problem with this approach
 * is that the individual ink jets are not perfectly uniform; some emit
 * slightly bigger or smaller drops than others.  Since each group of 8
 * adjacent rows is printed with the same nozzle, that means that there will
 * be distinct streaks of lighter and darker bands within the image (8 rows
 * is 1/90", which is visible; 1/720" is not).  Possibly worse is that these
 * patterns will repeat every 256 rows.  This creates banding patterns that
 * are about 1/3" wide.
 *
 * So we have to do something to break up this patterning.
 *
 * Epson does not publish the weaving algorithms that they use in their
 * bundled drivers.  Indeed, their developer web site
 * (http://www.ercipd.com/isv/edr_docs.htm) does not even describe how to
 * do this weaving at all; it says that the only way to achieve 720 dpi
 * is to use MicroWeave.  It does note (correctly) that 1440 dpi horizontal
 * can only be achieved by the driver (i. e. in software).  The manual
 * actually makes it fairly clear how to do this (it requires two passes
 * with horizontal head movement between passes), and it is presumably
 * possible to do this with MicroWeave.
 *
 * The information about how to do this is apparently available under NDA.
 * It's actually easy enough to reverse engineer what's inside a print file
 * with a simple Perl script.  There are presumably other printer commands
 * that are not documented and may not be as easy to reverse engineer.
 *
 * I considered a few algorithms to perform the weave.  The first one I
 * devised let me use only (jets - distance_between_jets + 1) nozzles, or
 * 25.  This is OK in principle, but it's slower than using all nozzles.
 * By playing around with it some more, I came up with an algorithm that
 * lets me use all of the nozzles, except near the top and bottom of the
 * page.
 *
 * This still produces some banding, though.  Even better quality can be
 * achieved by using multiple nozzles on the same line.  How do we do this?
 * In 1440x720 mode, we're printing two output lines at the same vertical
 * position.  However, if we want four passes, we have to effectively print
 * each line twice.  Actually doing this would increase the density, so
 * what we do is print half the dots on each pass.  This produces near-perfect
 * output, and it's far faster than using (pseudo) "MicroWeave".
 *
 * The current algorithm is not completely general.  The number of passes
 * is limited to (nozzles / gap).  On the Photo EX class printers, that limits
 * it to 4 -- 32 nozzles, an inter-nozzle gap of 8 lines.  Furthermore, there
 * are a number of routines that are only coded up to 8 passes.  Fortunately,
 * this is enough passes to get rid of most banding.  What's left is a very
 * fine pattern that is sometimes described as "corduroy", since the pattern
 * looks like that kind of fabric.
 *
 * Newer printers (those that support variable dot sizes, such as the 740,
 * 1200, etc.) have an additional complication: when used in softweave mode,
 * they operate at 360 dpi horizontal resolution.  This requires FOUR passes
 * to achieve 1440x720 dpi.  Thus, to enable us to break up each row
 * into separate sub-rows, we have to actually print each row eight times.
 * Fortunately, all such printers have 48 nozzles and a gap of 6 rows,
 * except for the high-speed 900, which uses 96 nozzles and a gap of 2 rows.
 *
 * I cannot let this entirely pass without commenting on the Stylus Color 440.
 * This is a very low-end printer with 21 (!) nozzles and a separation of 8.
 * The weave routine works correctly with single-pass printing, which is enough
 * to minimally achieve 720 dpi output (it's physically a 720 dpi printer).
 * However, the routine does not work correctly at more than one pass per row.
 * Therefore, this printer bands badly.
 *
 * Yet another complication is how to get near the top and bottom of the page.
 * This algorithm lets us print to within one head width of the top of the
 * page, and a bit more than one head width from the bottom.  That leaves a
 * lot of blank space.  Doing the weave properly outside of this region is
 * increasingly difficult as we get closer to the edge of the paper; in the
 * interior region, any nozzle can print any line, but near the top and
 * bottom edges, only some nozzles can print.  We've handled this for now by
 * using the naive way mentioned above near the borders, and switching over
 * to the high quality method in the interior.  Unfortunately, this means
 * that the quality is quite visibly degraded near the top and bottom of the
 * page.  Algorithms that degrade more gracefully are more complicated.
 * Epson does not advertise that the printers can print at the very top of the
 * page, although in practice most or all of them can.  I suspect that the
 * quality that can be achieved very close to the top is poor enough that
 * Epson does not want to allow printing there.  That is a valid decision,
 * although we have taken another approach.
 *
 * To compute the weave information, we need to start with the following
 * information:
 *
 * 1) The number of jets the print head has for each color;
 *
 * 2) The separation in rows between the jets;
 *
 * 3) The horizontal resolution of the printer;
 *
 * 4) The desired horizontal resolution of the output;
 *
 * 5) The desired extra passes to reduce banding.
 *
 * As discussed above, each row is actually printed in one or more passes
 * of the print head; we refer to these as subpasses.  For example, if we're
 * printing at 1440(h)x720(v) on a printer with true horizontal resolution of
 * 360 dpi, and we wish to print each line twice with different nozzles
 * to reduce banding, we need to use 8 subpasses.  The dither routine
 * will feed us a complete row of bits for each color; we have to split that
 * up, first by round robining the bits to ensure that they get printed at
 * the right micro-position, and then to split up the bits that are actually
 * turned on into two equal chunks to reduce banding.
 *
 * Given the above information, and the desired row index and subpass (which
 * together form a line number), we can compute:
 *
 * 1) Which pass this line belongs to.  Passes are numbered consecutively,
 *    and each pass must logically (see #3 below) start at no smaller a row
 *    number than the previous pass, as the printer cannot advance by a
 *    negative amount.
 *
 * 2) Which jet will print this line.
 *
 * 3) The "logical" first line of this pass.  That is, what line would be
 *    printed by jet 0 in this pass.  This number may be less than zero.
 *    If it is, there are ghost lines that don't actually contain any data.
 *    The difference between the logical first line of this pass and the
 *    logical first line of the preceding pass tells us how many lines must
 *    be advanced.
 *
 * 4) The "physical" first line of this pass.  That is, the first line index
 *    that is actually printed in this pass.  This information lets us know
 *    when we must prepare this pass.
 *
 * 5) The last line of this pass.  This lets us know when we must actually
 *    send this pass to the printer.
 *
 * 6) The number of ghost rows this pass contains.  We must still send the
 *    ghost data to the printer, so this lets us know how much data we must
 *    fill in prior to the start of the pass.
 *
 * The bookkeeping to keep track of all this stuff is quite hairy, and needs
 * to be documented separately.
 *
 * The routine initialize_weave calculates the basic parameters, given
 * the number of jets and separation between jets, in rows.
 *
 * -- Robert Krawitz <rlk@alum.mit.edu) November 3, 1999
 */

static stp_lineoff_t *
allocate_lineoff(int count, int ncolors)
{
  int i;
  stp_lineoff_t *retval = stp_malloc(count * sizeof(stp_lineoff_t));
  for (i = 0; i < count; i++)
    {
      retval[i].ncolors = ncolors;
      retval[i].v = stp_zalloc(ncolors * sizeof(unsigned long));
    }
  return (retval);
}

static stp_lineactive_t *
allocate_lineactive(int count, int ncolors)
{
  int i;
  stp_lineactive_t *retval = stp_malloc(count * sizeof(stp_lineactive_t));
  for (i = 0; i < count; i++)
    {
      retval[i].ncolors = ncolors;
      retval[i].v = stp_zalloc(ncolors * sizeof(char));
    }
  return (retval);
}

static stp_linecount_t *
allocate_linecount(int count, int ncolors)
{
  int i;
  stp_linecount_t *retval = stp_malloc(count * sizeof(stp_linecount_t));
  for (i = 0; i < count; i++)
    {
      retval[i].ncolors = ncolors;
      retval[i].v = stp_zalloc(ncolors * sizeof(int));
    }
  return (retval);
}

static stp_linebounds_t *
allocate_linebounds(int count, int ncolors)
{
  int i;
  stp_linebounds_t *retval = stp_malloc(count * sizeof(stp_linebounds_t));
  for (i = 0; i < count; i++)
    {
      retval[i].ncolors = ncolors;
      retval[i].start_pos = stp_zalloc(ncolors * sizeof(int));
      retval[i].end_pos = stp_zalloc(ncolors * sizeof(int));
    }
  return (retval);
}

static stp_linebufs_t *
allocate_linebuf(int count, int ncolors)
{
  int i;
  stp_linebufs_t *retval = stp_malloc(count * sizeof(stp_linebufs_t));
  for (i = 0; i < count; i++)
    {
      retval[i].ncolors = ncolors;
      retval[i].v = stp_zalloc(ncolors * sizeof(unsigned char *));
    }
  return (retval);
}

/*
 * Initialize the weave parameters
 *
 * Rules:
 *
 * 1) Currently, osample * v_subpasses * v_subsample <= 8, and no one
 *    of these variables may exceed 4.
 *
 * 2) first_line >= 0
 *
 * 3) line_height < physlines
 *
 * 4) page_height >= 2 * jets * sep
 */

static void
stpi_destroy_weave(void *vsw)
{
  int i, j;
  stpi_softweave_t *sw = (stpi_softweave_t *) vsw;
  stp_free(sw->passes);
  if (sw->fold_buf)
    stp_free(sw->fold_buf);
  if (sw->comp_buf)
    stp_free(sw->comp_buf);
  for (i = 0; i < STP_MAX_WEAVE; i++)
    if (sw->s[i])
      stp_free(sw->s[i]);
  for (i = 0; i < sw->vmod; i++)
    {
      for (j = 0; j < sw->ncolors; j++)
	{
	  if (sw->linebases[i].v[j])
	    stp_free(sw->linebases[i].v[j]);
	}
      stp_free(sw->linecounts[i].v);
      stp_free(sw->linebases[i].v);
      stp_free(sw->lineactive[i].v);
      stp_free(sw->lineoffsets[i].v);
      stp_free(sw->linebounds[i].start_pos);
      stp_free(sw->linebounds[i].end_pos);
    }
  stp_free(sw->linecounts);
  stp_free(sw->lineactive);
  stp_free(sw->lineoffsets);
  stp_free(sw->linebases);
  stp_free(sw->linebounds);
  stp_free(sw->head_offset);
  stpi_destroy_weave_params(sw->weaveparm);
  stp_free(vsw);
}

void
stp_initialize_weave(stp_vars_t *v,
		     int jets,	/* Width of print head */
		     int sep,	/* Separation in rows between jets */
		     int osample,	/* Horizontal oversample */
		     int v_subpasses, /* Vertical passes */
		     int v_subsample, /* Vertical oversampling */
		     int ncolors,
		     int bitwidth,	/* bits/pixel */
		     int linewidth,	/* Width of a line, in pixels */
		     int line_count, /* Lines that will be printed */
		     int first_line, /* First line that will be printed */
		     int page_height, /* Total height of the page in rows */
		     const int *head_offset,
		     stp_weave_strategy_t weave_strategy,
		     stp_flushfunc flushfunc,
		     stp_fillfunc fillfunc,
		     stp_packfunc pack,
		     stp_compute_linewidth_func compute_linewidth)
{
  int i;
  int last_line, maxHeadOffset;
  stpi_softweave_t *sw = stp_zalloc(sizeof (stpi_softweave_t));

  if (jets < 1)
    jets = 1;
  if (jets == 1 || sep < 1)
    sep = 1;
  if (v_subpasses < 1)
    v_subpasses = 1;
  if (v_subsample < 1)
    v_subsample = 1;

  sw->separation = sep;
  sw->jets = jets;
  sw->horizontal_weave = osample;
  sw->oversample = osample * v_subpasses * v_subsample;
  if (sw->oversample > jets)
    {
      int found = 0;
      for (i = 2; i <= osample; i++)
	{
	  if ((osample % i == 0) && (sw->oversample / i <= jets))
	    {
	      sw->repeat_count = i;
	      osample /= i;
	      found = 1;
	      break;
	    }
	}
      if (!found)
	{
	  stp_eprintf(v, "Weave error: oversample (%d) > jets (%d)\n",
		      sw->oversample, jets);
	  stp_free(sw);
	  return;
	}
    }
  else
    sw->repeat_count = 1;

  sw->vertical_oversample = v_subsample;
  sw->vertical_subpasses = v_subpasses;
  sw->oversample = osample * v_subpasses * v_subsample;
  sw->firstline = first_line;
  sw->lineno = first_line;
  sw->flushfunc = flushfunc;

  if (sw->oversample > jets)
    {
      stp_eprintf(v, "Weave error: oversample (%d) > jets (%d)\n",
		  sw->oversample, jets);
      stp_free(sw);
      return;
    }

  /*
   * setup printhead offsets.
   * for monochrome (bw) printing, the offsets are 0.
   */
  sw->head_offset = stp_zalloc(ncolors * sizeof(int));
  if (ncolors > 1)
    for(i = 0; i < ncolors; i++)
      sw->head_offset[i] = head_offset[i];

  maxHeadOffset = 0;
  for (i = 0; i < ncolors; i++)
    if (sw->head_offset[i] > maxHeadOffset)
      maxHeadOffset = sw->head_offset[i];

  sw->virtual_jets = sw->jets;
  if (maxHeadOffset > 0)
    sw->virtual_jets += (maxHeadOffset + sw->separation - 1) / sw->separation;
  last_line = first_line + line_count - 1 + maxHeadOffset;

  sw->weaveparm = initialize_weave_params(sw->separation, sw->jets,
                                          sw->oversample, first_line, last_line,
                                          page_height, weave_strategy, v);
  /*
   * The value of vmod limits how many passes may be unfinished at a time.
   * If pass x is not yet printed, pass x+vmod cannot be started.
   *
   * The multiplier of 2: 1 for the normal passes, 1 for the special passes
   * at the start or end.
   */
  sw->vmod = 2 * sw->separation * sw->oversample * sw->repeat_count;
  if (sw->virtual_jets > sw->jets)
    sw->vmod *= (sw->virtual_jets + sw->jets - 1) / sw->jets;

  sw->bitwidth = bitwidth;
  sw->last_pass_offset = 0;
  sw->last_pass = -1;
  sw->current_vertical_subpass = 0;
  sw->ncolors = ncolors;
  sw->linewidth = linewidth;
  sw->vertical_height = line_count;
  sw->lineoffsets = allocate_lineoff(sw->vmod, ncolors);
  sw->lineactive = allocate_lineactive(sw->vmod, ncolors);
  sw->linebases = allocate_linebuf(sw->vmod, ncolors);
  sw->linebounds = allocate_linebounds(sw->vmod, ncolors);
  sw->passes = stp_zalloc(sw->vmod * sizeof(stp_pass_t));
  sw->linecounts = allocate_linecount(sw->vmod, ncolors);
  sw->rcache = -2;
  sw->vcache = -2;
  sw->fillfunc = fillfunc;
  sw->compute_linewidth = compute_linewidth;
  sw->pack = pack;
  sw->horizontal_width =
    (sw->compute_linewidth)(v, ((sw->linewidth + sw->horizontal_weave - 1) /
				 sw->horizontal_weave));
  stp_dprintf(STP_DBG_WEAVE_PARAMS, v,
	      "Computing linewidth for linewidth %d weave %d => %d (%d)\n",
	      sw->linewidth, sw->horizontal_weave, sw->horizontal_width,
	      ((sw->horizontal_width + 7) / 8));
  sw->horizontal_width = ((sw->horizontal_width + 7) / 8);

  for (i = 0; i < sw->vmod; i++)
    {
      int j;
      sw->passes[i].pass = -1;
      for (j = 0; j < sw->ncolors; j++)
	{
	  sw->linebases[i].v[j] = NULL;
	}
    }
  stp_dprintf(STP_DBG_WEAVE_PARAMS, v,
	      "Weave parameters: separation %d jets %d (%d) h %d v %d v_sub %d\n",
	      sw->separation, sw->jets, sw->virtual_jets, osample,
	      v_subpasses, v_subsample);
  stp_dprintf(STP_DBG_WEAVE_PARAMS, v,
	      "      ncolors %d bpp %d width %d (%d) line_count %d first %d last %d max_offset %d\n",
	      sw->ncolors, sw->bitwidth, linewidth, sw->horizontal_width,
	      sw->vertical_height, first_line, last_line, maxHeadOffset);
  stp_dprintf(STP_DBG_WEAVE_PARAMS, v,
	      "      oversample %d line buffer count %d total buffer %d, page_height %d\n",
	      sw->oversample, sw->vmod,
	      sw->vmod * sw->virtual_jets * sw->bitwidth *
	      sw->ncolors * sw->horizontal_width, page_height);
  stp_dprintf(STP_DBG_WEAVE_PARAMS, v,
	      "      ***Buffer limit %d (vj %d bw %d hw %d)\n",
	      sw->virtual_jets * sw->bitwidth * sw->horizontal_width,
	      sw->virtual_jets, sw->bitwidth, sw->horizontal_width);
  stp_allocate_component_data(v, "Weave", NULL, stpi_destroy_weave, sw);
  return;
}

static void
weave_parameters_by_row(const stp_vars_t *v, stpi_softweave_t *sw,
			int row, int vertical_subpass, stp_weave_t *w)
{
  int jetsused;
  int sub_repeat_count = vertical_subpass % sw->repeat_count;
  /*
   * Conceptually, this does not modify the softweave state.  We cache
   * the results, but this cache is considered hidden.
   */
  vertical_subpass /= sw->repeat_count;

  if (sw->rcache == row && sw->vcache == vertical_subpass)
    {
      memcpy(w, &sw->wcache, sizeof(stp_weave_t));
      w->pass = (w->pass * sw->repeat_count) + sub_repeat_count;
      return;
    }
  sw->rcache = row;
  sw->vcache = vertical_subpass;

  w->row = row;
  stpi_calculate_row_parameters(sw->weaveparm, row, vertical_subpass,
				&w->pass, &w->jet, &w->logicalpassstart,
				&w->missingstartrows, &jetsused);

  w->physpassstart = w->logicalpassstart + sw->separation * w->missingstartrows;
  w->physpassend = w->physpassstart + sw->separation * (jetsused - 1);

  memcpy(&(sw->wcache), w, sizeof(stp_weave_t));
  w->pass = (w->pass * sw->repeat_count) + sub_repeat_count;
  stp_dprintf(STP_DBG_ROWS, v, "row %d, jet %d of pass %d "
	      "(pos %d, start %d, end %d, missing rows %d)\n",
	      w->row, w->jet, w->pass, w->logicalpassstart, w->physpassstart,
	      w->physpassend, w->missingstartrows);
}

static stpi_softweave_t *
get_sw(const stp_vars_t *v)
{
  return (stpi_softweave_t *) stp_get_component_data(v, "Weave");
}

void
stp_weave_parameters_by_row(const stp_vars_t *v, int row,
			    int vertical_subpass, stp_weave_t *w)
{
  stpi_softweave_t *sw = get_sw(v);
  weave_parameters_by_row(v, sw, row, vertical_subpass, w);
}


static stp_lineoff_t *
stpi_get_lineoffsets(const stp_vars_t *v, stpi_softweave_t *sw,
		     int row, int subpass, int offset)
{
  stp_weave_t w;
  weave_parameters_by_row(v, sw, row + offset, subpass, &w);
  return &(sw->lineoffsets[w.pass % sw->vmod]);
}

static stp_lineactive_t *
stpi_get_lineactive(const stp_vars_t *v, stpi_softweave_t *sw,
		    int row, int subpass, int offset)
{
  stp_weave_t w;
  weave_parameters_by_row(v, sw, row + offset, subpass, &w);
  return &(sw->lineactive[w.pass % sw->vmod]);
}

static stp_linecount_t *
stpi_get_linecount(const stp_vars_t *v, stpi_softweave_t *sw,
		   int row, int subpass, int offset)
{
  stp_weave_t w;
  weave_parameters_by_row(v, sw, row + offset, subpass, &w);
  return &(sw->linecounts[w.pass % sw->vmod]);
}

static stp_linebufs_t *
stpi_get_linebases(const stp_vars_t *v, stpi_softweave_t *sw,
		   int row, int subpass, int offset)
{
  stp_weave_t w;
  weave_parameters_by_row(v, sw, row + offset, subpass, &w);
  return &(sw->linebases[w.pass % sw->vmod]);
}

static stp_linebounds_t *
stpi_get_linebounds(const stp_vars_t *v, stpi_softweave_t *sw,
		    int row, int subpass, int offset)
{
  stp_weave_t w;
  weave_parameters_by_row(v, sw, row + offset, subpass, &w);
  return &(sw->linebounds[w.pass % sw->vmod]);
}

static stp_pass_t *
stpi_get_pass_by_row(stp_vars_t *v, stpi_softweave_t *sw,
		     int row, int subpass,int offset)
{
  stp_weave_t w;
  weave_parameters_by_row(v, sw, row + offset, subpass, &w);
  return &(sw->passes[w.pass % sw->vmod]);
}

stp_lineoff_t *
stp_get_lineoffsets_by_pass(const stp_vars_t *v, int pass)
{
  const stpi_softweave_t *sw = get_sw(v);
  return &(sw->lineoffsets[pass % sw->vmod]);
}

stp_lineactive_t *
stp_get_lineactive_by_pass(const stp_vars_t *v, int pass)
{
  const stpi_softweave_t *sw = get_sw(v);
  return &(sw->lineactive[pass % sw->vmod]);
}

stp_linecount_t *
stp_get_linecount_by_pass(const stp_vars_t *v, int pass)
{
  const stpi_softweave_t *sw = get_sw(v);
  return &(sw->linecounts[pass % sw->vmod]);
}

const stp_linebufs_t *
stp_get_linebases_by_pass(const stp_vars_t *v, int pass)
{
  const stpi_softweave_t *sw = get_sw(v);
  return &(sw->linebases[pass % sw->vmod]);
}

stp_pass_t *
stp_get_pass_by_pass(const stp_vars_t *v, int pass)
{
  const stpi_softweave_t *sw = get_sw(v);
  return &(sw->passes[pass % sw->vmod]);
}

static void
check_linebases(stp_vars_t *v, stpi_softweave_t *sw,
		int row, int cpass, int head_offset, int color)
{
  stp_linebufs_t *bufs =
    (stp_linebufs_t *) stpi_get_linebases(v, sw, row, cpass, head_offset);
  if (!(bufs->v[color]))
    bufs->v[color] =
      stp_zalloc (sw->virtual_jets * sw->bitwidth * sw->horizontal_width);
}

/*
 * If there are phantom rows at the beginning of a pass, fill them in so
 * that the printer knows exactly what it doesn't have to print.  We're
 * using RLE compression here.  Each line must be specified independently,
 * so we have to compute how many full blocks (groups of 128 bytes, or 1024
 * "off" pixels) and how much leftover is needed.  Note that we can only
 * RLE-encode groups of 2 or more bytes; single bytes must be specified
 * with a count of 1.
 */

void
stp_fill_tiff(stp_vars_t *v, int row, int subpass,
	      int width, int missingstartrows, int color)
{
  stpi_softweave_t *sw = get_sw(v);
  stp_lineoff_t *lineoffs;
  stp_linecount_t *linecount;
  const stp_linebufs_t *bufs;
  int i = 0;
  int k = 0;

  width = sw->bitwidth * width * 8;
  for (k = 0; k < missingstartrows; k++)
    {
      int bytes_to_fill = width;
      int full_blocks = bytes_to_fill / (128 * 8);
      int leftover = (7 + (bytes_to_fill % (128 * 8))) / 8;
      int l = 0;
      bufs = stpi_get_linebases(v, sw, row, subpass, sw->head_offset[color]);

      while (l < full_blocks)
	{
	  (bufs->v[color][2 * i]) = 129;
	  (bufs->v[color][2 * i + 1]) = 0;
	  i++;
	  l++;
	}
      if (leftover == 1)
	{
	  (bufs->v[color][2 * i]) = 1;
	  (bufs->v[color][2 * i + 1]) = 0;
	  i++;
	}
      else if (leftover > 0)
	{
	  (bufs->v[color][2 * i]) = 257 - leftover;
	  (bufs->v[color][2 * i + 1]) = 0;
	  i++;
	}
    }

  lineoffs = stpi_get_lineoffsets(v, sw, row, subpass, sw->head_offset[color]);
  linecount = stpi_get_linecount(v, sw, row, subpass, sw->head_offset[color]);
  lineoffs->v[color] = 2 * i;
  linecount->v[color] = missingstartrows;
}

void
stp_fill_uncompressed(stp_vars_t *v, int row, int subpass,
		      int width, int missingstartrows, int color)
{
  stpi_softweave_t *sw = get_sw(v);
  stp_lineoff_t *lineoffs;
  stp_linecount_t *linecount;
  const stp_linebufs_t *bufs;

  bufs = stpi_get_linebases(v, sw, row, subpass, sw->head_offset[color]);
  lineoffs = stpi_get_lineoffsets(v, sw, row, subpass, sw->head_offset[color]);
  linecount = stpi_get_linecount(v, sw, row, subpass, sw->head_offset[color]);
  width *= sw->bitwidth * missingstartrows;
  memset(bufs->v[color], 0, width);
  lineoffs->v[color] = width;
  linecount->v[color] = missingstartrows;
}

int
stp_compute_tiff_linewidth(stp_vars_t *v, int n)
{
  /*
   * It's possible for the "compression" to actually expand the line by
   * roughly one part in 128.
   */
  return ((n + 128 + 7) * 129 / 128);
}

int
stp_compute_uncompressed_linewidth(stp_vars_t *v, int n)
{
  return (8 * ((n + 7) / 8));
}

static void
initialize_row(stp_vars_t *v, stpi_softweave_t *sw,
	       int row, int width, unsigned char *const cols[])
{
  stp_weave_t w;
  int i, j, jj;
  stp_pass_t *pass;

  for (i = 0; i < sw->oversample; i++)
    {
      for (j = 0; j < sw->ncolors; j++)
	{
	  if (cols[j])
	    {
	      stp_lineoff_t *lineoffs =
		stpi_get_lineoffsets(v, sw, row, i, sw->head_offset[j]);
	      stp_lineactive_t *lineactive =
		stpi_get_lineactive(v, sw, row, i, sw->head_offset[j]);
	      stp_linecount_t *linecount =
		stpi_get_linecount(v, sw, row, i, sw->head_offset[j]);
	      stp_linebounds_t *linebounds =
		stpi_get_linebounds(v, sw, row, i, sw->head_offset[j]);
	      check_linebases(v, sw, row, i, sw->head_offset[j], j);
	      weave_parameters_by_row(v, sw, row+sw->head_offset[j], i, &w);
	      pass = stpi_get_pass_by_row(v, sw, row, i, sw->head_offset[j]);

	      /* initialize pass if not initialized yet */
	      if (pass->pass < 0)
		{
		  pass->pass = w.pass;
		  pass->missingstartrows = w.missingstartrows;
		  pass->logicalpassstart = w.logicalpassstart;
		  pass->physpassstart = w.physpassstart;
		  pass->physpassend = w.physpassend;
		  pass->subpass = i;

		  for(jj=0; jj<sw->ncolors; jj++)
		    {
		      if (lineoffs->v[jj] != 0)
			stp_eprintf(v, "WARNING: pass %d subpass %d row %d: "
				    "lineoffs %ld should be zero!\n",
				    w.pass, i, row, lineoffs->v[jj]);
		      lineoffs->v[jj] = 0;
		      lineactive->v[jj] = 0;
		      if (linecount->v[jj] != 0)
			stp_eprintf(v, "WARNING: pass %d subpass %d row %d: "
				    "linecount %d should be zero!\n",
				    w.pass, i, row, linecount->v[jj]);
		      linecount->v[jj] = 0;
		      linebounds->start_pos[jj] = INT_MAX;
		      linebounds->end_pos[jj] = -1;
		    }
		}

	      if((linecount->v[j] == 0) && (w.jet > 0))
		{
		  (sw->fillfunc)(v, row, i, width, w.jet, j);
		}
	    }
	}
    }
}

static void
add_to_row_1(stp_vars_t *v, stpi_softweave_t *sw, int row, unsigned char *buf,
	     size_t nbytes, int color, int setactive, int h_pass)
{
  const stp_linebufs_t *bufs =
    stpi_get_linebases(v, sw, sw->lineno, h_pass, sw->head_offset[color]);
  stp_lineoff_t *lineoffs =
    stpi_get_lineoffsets(v, sw, sw->lineno, h_pass, sw->head_offset[color]);
  stp_lineactive_t *lineactive =
    stpi_get_lineactive(v, sw, sw->lineno, h_pass, sw->head_offset[color]);
  stp_linecount_t *linecount =
    stpi_get_linecount(v, sw, sw->lineno, h_pass, sw->head_offset[color]);
  size_t place = lineoffs->v[color];
  size_t count = linecount->v[color];
  if (place + nbytes > sw->virtual_jets * sw->bitwidth * sw->horizontal_width)
    {
      int i;
      stp_eprintf(v, "ERROR: %s\n", _("Fatal error!"));
      stp_eprintf(v, "ERROR: Static weave data follows:\n");
      stp_eprintf(v, "ERROR:    jets: %d\n", sw->jets);
      stp_eprintf(v, "ERROR:    virtual_jets: %d\n", sw->virtual_jets);
      stp_eprintf(v, "ERROR:    separation: %d\n", sw->separation);
      stp_eprintf(v, "ERROR:    horizontal_weave: %d\n", sw->horizontal_weave);
      stp_eprintf(v, "ERROR:    vertical_subpasses: %d\n", sw->vertical_subpasses);
      stp_eprintf(v, "ERROR:    vmod: %d\n", sw->vmod);
      stp_eprintf(v, "ERROR:    oversample: %d\n", sw->oversample);
      stp_eprintf(v, "ERROR:    repeat_count: %d\n", sw->repeat_count);
      stp_eprintf(v, "ERROR:    ncolors: %d\n", sw->ncolors);
      stp_eprintf(v, "ERROR:    linewidth: %d\n", sw->linewidth);
      stp_eprintf(v, "ERROR:    vertical_height: %d\n", sw->vertical_height);
      stp_eprintf(v, "ERROR:    firstline: %d\n", sw->firstline);
      stp_eprintf(v, "ERROR:    bitwidth: %d\n", sw->bitwidth);
      stp_eprintf(v, "ERROR:    vertical_oversample: %d\n", sw->vertical_oversample);
      stp_eprintf(v, "ERROR:    horizontal_width: %d\n", sw->horizontal_width);
      if (sw->head_offset)
	{
	  stp_eprintf(v, "ERROR:    head_offset:\n");
	  for (i = 0; i < sw->ncolors; i++)
	    stp_eprintf(v, "ERROR:      head %d: %d\n", i, sw->head_offset[i]);
	}
      stp_eprintf(v, "ERROR: Dynamic weave data follows:\n");
      stp_eprintf(v, "ERROR:    last_pass_offset: %d\n", sw->last_pass_offset);
      stp_eprintf(v, "ERROR:    last_pass: %d\n", sw->last_pass);
      stp_eprintf(v, "ERROR:    lineno: %d\n", sw->lineno);
      stp_eprintf(v, "ERROR:    current_vertical_subpass: %d\n", sw->current_vertical_subpass);
      stp_eprintf(v, "ERROR:    rcache: %d\n", sw->rcache);
      stp_eprintf(v, "ERROR:    vcache: %d\n", sw->vcache);
      stp_eprintf(v, "ERROR: Other parameters: row %d color %d setactive %d hpass %d\n",
		  row, color, setactive, h_pass);
      stp_eprintf(v, "ERROR: Buffer overflow: limit %d (jets %d bits %d horizontal %d), actual %ld (current %d added %d), count %ld\n",
		  sw->virtual_jets * sw->bitwidth * sw->horizontal_width,
		  sw->virtual_jets, sw->bitwidth, sw->horizontal_width,
		  (long) (place + nbytes), (int) place, (int) nbytes, (long) count);
      stp_eprintf(v, "ERROR: %s\n", _("Please report the above information to gimp-print-devel@lists.sourceforge.net"));
      stp_abort();
    }
  memcpy(bufs->v[color] + lineoffs->v[color], buf, nbytes);
  lineoffs->v[color] += nbytes;
  if (setactive)
    lineactive->v[color] = 1;
}

static void
add_to_row(stp_vars_t *v, stpi_softweave_t *sw, int row, unsigned char *buf,
	   size_t nbytes, int color, int setactive, int h_pass)
{
  if (!sw->head_offset)
    {
      stp_eprintf(v, "ERROR: %s\n", _("Fatal error!"));
      stp_eprintf(v, "ERROR: add_to_row: sw->head_offset == NULL\n");
      return;
    }
  add_to_row_1(v, sw, row, buf, nbytes, color, setactive, h_pass);
}

static void
stpi_flush_passes(stp_vars_t *v, int flushall)
{
  stpi_softweave_t *sw = get_sw(v);
  while (1)
    {
      stp_pass_t *pass = stp_get_pass_by_pass(v, sw->last_pass + 1);
      /*
       * This ought to be   pass->physpassend >  sw->lineno
       * but that causes rubbish to be output for some reason.
       */
      if (pass->pass < 0 || (!flushall && pass->physpassend >= sw->lineno))
	return;
      (sw->flushfunc)(v, pass->pass, pass->subpass);
      sw->last_pass = pass->pass;
      pass->pass = -1;
    }
}

void
stp_flush_all(stp_vars_t *v)
{
  stpi_flush_passes(v, 1);
}

static void
finalize_row(stp_vars_t *v, int row)
{
  stpi_softweave_t *sw = get_sw(v);
  int i,j;
  stp_dprintf(STP_DBG_ROWS, v, "Finalizing row %d...\n", row);
  for (i = 0; i < sw->oversample; i++)
    {
      stp_weave_t w;
      stp_linecount_t *lines;

      for(j=0; j<sw->ncolors; j++)
        {
	  lines = stpi_get_linecount(v, sw, row, i, sw->head_offset[j]);
	  lines->v[j]++;
        }

      weave_parameters_by_row(v, sw, row, i, &w);
      if (w.physpassend == row)
	{
	  stp_dprintf(STP_DBG_ROWS, v,
		      "Pass=%d, physpassend=%d, row=%d, lineno=%d, flush..\n",
		      w.pass, w.physpassend, row, sw->lineno);
	  stpi_flush_passes(v, 0);
	}
    }
}

void
stp_write_weave(stp_vars_t *v, unsigned char *const cols[])
{
  stpi_softweave_t *sw = get_sw(v);
  int length = (sw->linewidth + 7) / 8;
  stp_linebounds_t *linebounds[STP_MAX_WEAVE];
  int xlength = (length + sw->horizontal_weave - 1) / sw->horizontal_weave;
  int ylength = xlength * sw->horizontal_weave;
  unsigned char *comp_ptr;
  int i, j;
  int setactive;
  int h_passes = sw->horizontal_weave * sw->vertical_subpasses;
  int cpass = sw->current_vertical_subpass * h_passes;

  if (!sw->fold_buf)
    {
      stp_dprintf(STP_DBG_WEAVE_PARAMS, v,
		  "fold buffer allocation: length %d lw %d weave %d xlength %d ylength %d\n",
		  length, sw->linewidth, sw->horizontal_weave, xlength, ylength);
      stp_dprintf(STP_DBG_WEAVE_PARAMS, v,
		  "Allocating fold buf %d * %d (%d)\n", ylength, sw->bitwidth,
		  sw->bitwidth * ylength);
      sw->fold_buf = stp_zalloc(sw->bitwidth * ylength);
    }
  if (!sw->comp_buf)
    {
      stp_dprintf(STP_DBG_WEAVE_PARAMS, v,
		  "Allocating compression buffer based on %d, %d\n",
		  sw->bitwidth, ylength);
      sw->comp_buf = stp_zalloc(sw->bitwidth *
				(sw->compute_linewidth)(v,ylength));
    }
  if (sw->current_vertical_subpass == 0)
    initialize_row(v, sw, sw->lineno, xlength, cols);

  for (j = 0; j < sw->ncolors; j++)
    {
      if (cols[j])
	{
	  const unsigned char *in;
	  int idx;

	  for (i = 0; i < h_passes; i++)
	    {
	      int offset = sw->head_offset[j];
	      int pass = cpass + i;
	      if (!sw->s[i])
		sw->s[i] = stp_zalloc(sw->bitwidth *
				      (sw->compute_linewidth)(v, ylength));
	      linebounds[i] =
		stpi_get_linebounds(v, sw, sw->lineno, pass, offset);
	    }

	  if (sw->bitwidth == 2)
	    {
	      stp_fold(cols[j], length, sw->fold_buf);
	      in = sw->fold_buf;
	    }
	  else
	    in = cols[j];
	  if (sw->horizontal_weave == 1)
	    memcpy(sw->s[0], in, length * sw->bitwidth);
	  else
	    stp_unpack(length, sw->bitwidth, sw->horizontal_weave, in, sw->s);
	  if (sw->vertical_subpasses > 1)
	    {
	      for (idx = 0; idx < sw->horizontal_weave; idx++)
		stp_split(length, sw->bitwidth, sw->vertical_subpasses,
			  sw->s[idx], sw->horizontal_weave, &(sw->s[idx]));
	    }
	  for (i = 0; i < h_passes; i++)
	    {
	      int first, last;
	      setactive = (sw->pack)(v, sw->s[i], sw->bitwidth * xlength,
				     sw->comp_buf, &comp_ptr, &first, &last);
	      if (first < linebounds[i]->start_pos[j])
		linebounds[i]->start_pos[j] = first;
	      if (last > linebounds[i]->end_pos[j])
		linebounds[i]->end_pos[j] = last;
	      add_to_row(v, sw, sw->lineno, sw->comp_buf,
			 comp_ptr - sw->comp_buf, j, setactive, cpass + i);
	    }
	}
    }
  sw->current_vertical_subpass++;
  if (sw->current_vertical_subpass >= sw->vertical_oversample)
    {
      finalize_row(v, sw->lineno);
      sw->lineno++;
      sw->current_vertical_subpass = 0;
    }
}

#if 0
#define TEST_RAW
#endif
#if 0
#define TEST_COOKED
#endif
#if 0
#define ACCUMULATE
#endif

#if defined(TEST_RAW) || defined(TEST_COOKED)
#define TEST
#endif

#ifdef TEST
#define MAXCOLLECT (1000)
#endif

#ifdef TEST_COOKED
static void
calculate_pass_parameters(cooked_t *w,		/* I - weave parameters */
                          int pass,		/* I - pass number ( >= 0) */
                          int *startrow,	/* O - print head position */
                          int *subpass,		/* O - subpass number */
			  int *phantomrows,	/* O - missing rows */
			  int *jetsused)	/* O - jets used to print */
{
	int raw_pass = pass + w->first_premapped_pass;
	int stagger = 0;
	int extra;

	if (raw_pass < w->first_normal_pass) {
		int i = 0;
		while (i + w->first_premapped_pass < w->first_normal_pass) {
			if (w->pass_premap[i] == pass) {
				raw_pass = i + w->first_premapped_pass;
				stagger = w->stagger_premap[i];
				break;
			}
			i++;
		}
	} else if (raw_pass >= w->first_postmapped_pass) {
		int i = 0;
		while (i + w->first_postmapped_pass < w->first_unused_pass) {
			if (w->pass_postmap[i] == pass) {
				raw_pass = i + w->first_postmapped_pass;
				stagger = w->stagger_postmap[i];
				break;
			}
			i++;
		}
	}

	calculate_raw_pass_parameters(&w->rw, raw_pass, startrow, subpass);
	*startrow -= w->rw.separation * w->rw.jets;
	*jetsused = w->rw.jets;
	*phantomrows = 0;

	*startrow += stagger * w->rw.separation;
	if (stagger < 0) {
		stagger = -stagger;
		*phantomrows += stagger;
	}
	*jetsused -= stagger;

	extra = w->first_row_printed - (*startrow + w->rw.separation * *phantomrows);
	extra = (extra + w->rw.separation - 1) / w->rw.separation;
	if (extra > 0) {
		*jetsused -= extra;
		*phantomrows += extra;
	}

	extra = *startrow + w->rw.separation * (*phantomrows + *jetsused - 1)
	          - w->last_row_printed;
	extra = (extra + w->rw.separation - 1) / w->rw.separation;
	if (extra > 0) {
		*jetsused -= extra;
	}
}
#endif /* TEST_COOKED */

#ifdef TEST

#ifdef ACCUMULATE
#define PUTCHAR(x) /* nothing */
#else
#define PUTCHAR(x) putchar(x)
#endif

static void
plotpass(int startrow, int phantomjets, int jetsused, int totaljets,
         int separation, int subpass, int *collect, int *prints)
{
	int hpos, i;

	for (hpos = 0; hpos < startrow; hpos++)
		PUTCHAR(' ');

	for (i = 0; i < phantomjets; i++) {
		int j;
		PUTCHAR('X');
		hpos++;
		for (j = 1; j < separation; j++) {
			PUTCHAR(' ');
			hpos++;
		}
	}

	for (; i < phantomjets + jetsused; i++) {
		if (i > phantomjets) {
			int j;
			for (j = 1; j < separation; j++) {
				PUTCHAR('-');
				hpos++;
			}
		}
		if (hpos < MAXCOLLECT) {
			if (collect[hpos] & 1 << subpass)
				PUTCHAR('^');
			else if (subpass < 10)
				PUTCHAR('0' + subpass);
			else
				PUTCHAR('A' + subpass - 10);
			collect[hpos] |= 1 << subpass;
			prints[hpos]++;
		} else {
			PUTCHAR('0' + subpass);
		}
		hpos++;
	}

	while (i++ < totaljets) {
		int j;
		for (j = 1; j < separation; j++) {
			PUTCHAR(' ');
			hpos++;
		}
		PUTCHAR('X');
	}
#ifdef ACCUMULATE
	for (i=0; i<=MAXCOLLECT; i++) {
		if (collect[i] == 0)
			putchar(' ');
		else if (collect[i] < 10)
			putchar('0'+collect[i]);
		else
			putchar('A'+collect[i]-10);
	}
#endif
	putchar('\n');
}
#endif /* TEST */

#ifdef TEST_COOKED
int
main(int ac, char *av[])
{
	int S         =ac>1 ? atoi(av[1]) : 4;
	int J         =ac>2 ? atoi(av[2]) : 12;
	int H         =ac>3 ? atoi(av[3]) : 1;
	int firstrow  =ac>4 ? atoi(av[4]) : 1;
	int lastrow   =ac>5 ? atoi(av[5]) : 100;
	int pageheight=ac>6 ? atoi(av[6]) : 1000;
	stp_weave_strategy_t strategy  =ac>7 ? atoi(av[7]) : 1;
	cooked_t *weave;
	int passes;

	int pass, x;
	int collect[MAXCOLLECT];
	int prints[MAXCOLLECT];

	memset(collect, 0, MAXCOLLECT*sizeof(int));
	memset(prints, 0, MAXCOLLECT*sizeof(int));
	printf("S=%d  J=%d  H=%d  firstrow=%d  lastrow=%d  "
	       "pageheight=%d  strategy=%d\n",
	       S, J, H, firstrow, lastrow, pageheight, strategy);

	weave = initialize_weave_params(S, J, H, firstrow, lastrow,
	                                pageheight, strategy);
	passes = weave->first_unused_pass - weave->first_premapped_pass;

	for (pass = 0; pass < passes; pass++) {
		int startrow, subpass, phantomjets, jetsused;

		calculate_pass_parameters(weave, pass, &startrow, &subpass,
		                          &phantomjets, &jetsused);

		plotpass(startrow, phantomjets, jetsused, J, S, subpass,
		         collect, prints);
	}

	for (pass=MAXCOLLECT - 1; prints[pass] == 0; pass--)
		;

	for (x=0; x<=pass; x++) {
		if (collect[x] < 10)
			putchar('0'+collect[x]);
		else
			putchar('A'+collect[x]-10);
	}
	putchar('\n');

	for (x=0; x<=pass; x++) {
		if (prints[x] < 10)
			putchar('0'+prints[x]);
		else
			putchar('A'+prints[x]-10);
	}
	putchar('\n');

	return 0;
}
#endif /* TEST_COOKED */

#ifdef TEST_RAW
int
main(int ac, char *av[])
{
	int S     =ac>1 ? atoi(av[1]) : 4;
	int J     =ac>2 ? atoi(av[2]) : 12;
	int h_pos =ac>3 ? atoi(av[3]) : 1;
	int h_over=ac>4 ? atoi(av[4]) : 1;
	int v_over=ac>5 ? atoi(av[5]) : 1;
	int H = h_pos * h_over * v_over;

	int pass, passes, x;
	int collect[MAXCOLLECT];
	int prints[MAXCOLLECT];
	raw_t raw;

	memset(collect, 0, MAXCOLLECT*sizeof(int));
	memset(prints, 0, MAXCOLLECT*sizeof(int));
	printf("S=%d  J=%d  H=%d\n", S, J, H);

	if (H > J) {
		printf("H > J, so this weave will not work!\n");
	}
	passes = S * H * 3;

	initialize_raw_weave(&raw, S, J, H);

	for (pass=0; pass<passes + S * H; pass++) {
		int startrow, subpass, phantomjets, jetsused;

		calculate_raw_pass_parameters(&raw, pass, &startrow, &subpass);
		phantomjets = 0;
		jetsused = J;

		plotpass(startrow, phantomjets, jetsused, J, S, subpass,
		         collect, prints);
	}
	for (pass=MAXCOLLECT - 1; prints[pass] == 0; pass--)
		;

	for (x=0; x<=pass; x++) {
		if (collect[x] < 10)
			putchar('0'+collect[x]);
		else
			putchar('A'+collect[x]-10);
	}
	putchar('\n');

	for (x=0; x<=pass; x++) {
		if (prints[x] < 10)
			putchar('0'+prints[x]);
		else
			putchar('A'+prints[x]-10);
	}
	putchar('\n');

	printf("  A  first row given by pass lookup doesn't match row lookup\n"
	       "  B  jet out of range\n"
	       "  C  given jet number of pass doesn't print this row\n"
	       "  D  subpass given by reverse lookup doesn't match requested subpass\n");

	for (x = S * J; x < S * J * 20; x++) {
		int h;
		for (h = 0; h < H; h++) {
			int pass, jet, start, first, subpass, z;
			int a=0, b=0, c=0, d=0;
			calculate_raw_row_parameters(&raw, x, h, &pass, &jet, &start);
			for (z=0; z < pass; z++) {
				putchar(' ');
			}
			printf("%d", jet);
			calculate_raw_pass_parameters(&raw, pass, &first, &subpass);
			if (first != start)
				a=1;
			if (jet < 0 || jet >= J)
				b=1;
			if (x != first + jet * S)
				c=1;
			if (subpass != h)
				d=1;
			if (a || b || c || d) {
				printf("    (");
				if (a) putchar('A');
				if (b) putchar('B');
				if (c) putchar('C');
				if (d) putchar('D');
				putchar(')');
				printf("\npass=%d first=%d start=%d jet=%d subpass=%d", pass, first, start, jet, subpass);
			}
			putchar('\n');
		}
		/* putchar('\n'); */
	}

	return 0;
}

#endif /* TEST_RAW */
