/* Copyright (C) 1989, 1995, 1996, 1997, 1998, 1999 artofcode LLC.  All rights reserved.
  
  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, write to the Free Software Foundation, Inc.,
  59 Temple Place, Suite 330, Boston, MA, 02111-1307.

*/

/*$Id: gxifast.c,v 1.4.2.1.2.1 2003/01/17 00:49:03 giles Exp $ */
/* Fast monochrome image rendering */
#include "gx.h"
#include "memory_.h"
#include "gpcheck.h"
#include "gsbittab.h"
#include "gserrors.h"
#include "gxfixed.h"
#include "gxarith.h"
#include "gxmatrix.h"
#include "gsccolor.h"
#include "gspaint.h"
#include "gsutil.h"
#include "gxdevice.h"
#include "gxcmap.h"
#include "gxdcolor.h"
#include "gxistate.h"
#include "gxdevmem.h"
#include "gdevmem.h"		/* for mem_mono_device */
#include "gxcpath.h"
#include "gximage.h"
#include "gzht.h"

/* Conditionally include statistics code. */
#ifdef DEBUG
#  define STATS
#endif

/* ------ Strategy procedure ------ */

/* Check the prototype. */
iclass_proc(gs_image_class_1_simple);

/* Use special fast logic for portrait or landscape black-and-white images. */
private irender_proc(image_render_skip);
private irender_proc(image_render_simple);
private irender_proc(image_render_landscape);
irender_proc_t
gs_image_class_1_simple(gx_image_enum * penum)
{
    irender_proc_t rproc;
    fixed ox = dda_current(penum->dda.pixel0.x);
    fixed oy = dda_current(penum->dda.pixel0.y);

    if (penum->use_rop || penum->spp != 1 || penum->bps != 1)
	return 0;
    switch (penum->posture) {
	case image_portrait:
	    {			/* Use fast portrait algorithm. */
		long dev_width =
		    fixed2long_pixround(ox + penum->x_extent.x) -
		    fixed2long_pixround(ox);

		if (dev_width != penum->rect.w) {
		    /*
		     * Add an extra align_bitmap_mod of padding so that
		     * we can align scaled rows with the device.
		     */
		    long line_size =
			bitmap_raster(any_abs(dev_width)) + align_bitmap_mod;

		    if (penum->adjust != 0 || line_size > max_uint)
			return 0;
		    /* Must buffer a scan line. */
		    penum->line_width = any_abs(dev_width);
		    penum->line_size = (uint) line_size;
		    penum->line = gs_alloc_bytes(penum->memory,
					    penum->line_size, "image line");
		    if (penum->line == 0) {
			gx_default_end_image(penum->dev,
					     (gx_image_enum_common_t *)penum,
					     false);
			return 0;
		    }
		}
		if_debug2('b', "[b]render=simple, unpack=copy; rect.w=%d, dev_width=%ld\n",
			  penum->rect.w, dev_width);
		rproc = image_render_simple;
		break;
	    }
	case image_landscape:
	    {			/* Use fast landscape algorithm. */
		long dev_width =
		    fixed2long_pixround(oy + penum->x_extent.y) -
		    fixed2long_pixround(oy);
		long line_size =
		    (dev_width = any_abs(dev_width),
		     bitmap_raster(dev_width) * 8 +
		     ROUND_UP(dev_width, 8) * align_bitmap_mod);

		if ((dev_width != penum->rect.w && penum->adjust != 0) ||
		    line_size > max_uint
		    )
		    return 0;
		/* Must buffer a group of 8N scan lines. */
		penum->line_width = dev_width;
		penum->line_size = (uint) line_size;
		penum->line = gs_alloc_bytes(penum->memory,
					     penum->line_size, "image line");
		if (penum->line == 0) {
		    gx_default_end_image(penum->dev,
					 (gx_image_enum_common_t *) penum,
					 false);
		    return 0;
		}
		penum->xi_next = penum->line_xy = fixed2int_var_rounded(ox);
		if_debug3('b', "[b]render=landscape, unpack=copy; rect.w=%d, dev_width=%ld, line_size=%ld\n",
			  penum->rect.w, dev_width, line_size);
		rproc = image_render_landscape;
		/* Precompute values needed for rasterizing. */
		penum->dxy =
		    float2fixed(penum->matrix.xy +
				fixed2float(fixed_epsilon) / 2);
		break;
	    }
	default:
	    return 0;
    }
    /* Precompute values needed for rasterizing. */
    penum->dxx =
	float2fixed(penum->matrix.xx + fixed2float(fixed_epsilon) / 2);
    /*
     * We don't want to spread the samples, but we have to reset unpack_bps
     * to prevent the buffer pointer from being incremented by 8 bytes per
     * input byte.
     */
    penum->unpack = sample_unpack_copy;
    penum->unpack_bps = 8;
    if (penum->use_mask_color) {
	/*
	 * Set the masked color as 'no_color' to make it transparent
	 *  according to the mask color range and the decoding.
	 */
	penum->masked = true;
	if (penum->mask_color.values[0] == 1) {
	    /* if v0 == 1, 1 is transparent since v1 must be == 1 to be a valid range */
	    color_set_pure(penum->map[0].inverted ? &penum->icolor0 : &penum->icolor1,
			gx_no_color_index);
	} else if (penum->mask_color.values[1] == 0) {
	    /* if v1 == 0, 0 is transparent since v0 must be == 0 to be a valid range */
	    color_set_pure(penum->map[0].inverted ? &penum->icolor1 : &penum->icolor0,
			gx_no_color_index);
	} else {
	    /*
	     * The only other possible in-range value is v0 = 0, v1 = 1.
	     * The image is completely transparent!
	     */
	    rproc = image_render_skip;
	}
	penum->map[0].decoding = sd_none;
    }
    return rproc;
}

/* ------ Rendering procedures ------ */

#define DC_IS_NULL(pdc)\
  (gx_dc_is_pure(pdc) && (pdc)->colors.pure == gx_no_color_index)

/* Skip over a completely transparent image. */
private int
image_render_skip(gx_image_enum * penum, const byte * buffer, int data_x,
		  uint w, int h, gx_device * dev)
{
    return h;
}

/*
 * Scale (and possibly reverse) one scan line of a monobit image.
 * This is used for both portrait and landscape image processing.
 * We pass in an x offset (0 <= line_x < align_bitmap_mod * 8) so that
 * we can align the result with the eventual device X.
 *
 * To be precise, the input to this routine is the w bits starting at
 * bit data_x in buffer.  These w bits expand to abs(x_extent) bits,
 * either inverted (zero = 0xff) or not (zero = 0), starting at bit
 * line_x in line which corresponds to coordinate
 * fixed2int_pixround(xcur + min(x_extent, 0)).  Note that the entire
 * bytes containing the first and last output bits are affected: the
 * other bits in those bytes are set to zero (i.e., the value of the
 * 'zero' argument).
 */
#ifdef STATS
struct stats_image_fast_s {
    long
         calls, all0s, all1s, runs, lbit0, byte00, byte01, byte02, byte03,
         byte04, rbit0, lbit1, byte1, rbit1, thin, thin2, nwide, bwide,
         nfill, bfill;
} stats_image_fast;
#  define INCS(stat) ++stats_image_fast.stat
#  define ADDS(stat, n) stats_image_fast.stat += n
#else
#  define INCS(stat) DO_NOTHING
#  define ADDS(stat, n) DO_NOTHING
#endif
inline private void
fill_row(byte *line, int line_x, uint raster, int value)
{
    memset(line + (line_x >> 3), value, raster - (line_x >> 3));
}
private void
image_simple_expand(byte * line, int line_x, uint raster,
		    const byte * buffer, int data_x, uint w,
		    fixed xcur, fixed x_extent, byte zero /* 0 or 0xff */ )
{
    int dbitx = data_x & 7;
    byte sbit = 0x80 >> dbitx;
    byte sbitmask = 0xff >> dbitx;
    uint wx = dbitx + w;
    gx_dda_fixed xl;
    gx_dda_step_fixed dxx4, dxx8, dxx16, dxx24, dxx32;
    register const byte *psrc = buffer + (data_x >> 3);

    /*
     * The following 3 variables define the end of the input data row.
     * We would put them in a struct, except that no compiler that we
     * know of will optimize individual struct members as though they
     * were simple variables (e.g., by putting them in registers).
     *
     * endp points to the byte that contains the bit just beyond the
     * end of the row.  endx gives the bit number of this bit within
     * the byte, with 0 being the *least* significant bit.  endbit is
     * a mask for this bit.
     */
    const byte *endp = psrc + (wx >> 3);
    int endx = ~wx & 7;
    byte endbit = 1 << endx;

    /*
     * The following 3 variables do the same for start of the last run
     * of the input row (think of it as a pointer to just beyond the
     * end of the next-to-last run).
     */
    const byte *stop = endp;
    int stopx;
    byte stopbit = endbit;
    byte data;
    byte one = ~zero;
    fixed xl0;

    if (w == 0)
	return;
    INCS(calls);

    /* Scan backward for the last transition. */
    if (stopbit == 0x80)
	--stop, stopbit = 1;
    else
	stopbit <<= 1;
    /* Now (stop, stopbit) give the last bit of the row. */
    {
	byte stopmask = -stopbit << 1;
	byte last = *stop;

	if (stop == psrc)	/* only 1 input byte */
	    stopmask &= sbitmask;
	if (last & stopbit) {
	    /* The last bit is a 1: look for a 0-to-1 transition. */
	    if (~last & stopmask) {	/* Transition in last byte. */
		last |= stopbit - 1;
	    } else {		/* No transition in the last byte. */
		while (stop > psrc && stop[-1] == 0xff)
		    --stop;
		if (stop == psrc ||
		    (stop == psrc + 1 && !(~*psrc & sbitmask))
		    ) {
		    /* The input is all 1s.  Clear the row and exit. */
		    INCS(all1s);
		    fill_row(line, line_x, raster, one);
		    return;
		}
		last = *--stop;
	    }
	    stopx = byte_bit_run_length_0[byte_reverse_bits[last]] - 1;
	} else {
	    /* The last bit is a 0: look for a 1-to-0 transition. */
	    if (last & stopmask) {	/* Transition in last byte. */
		last &= -stopbit;
	    } else {		/* No transition in the last byte. */
		while (stop > psrc && stop[-1] == 0)
		    --stop;
		if (stop == psrc ||
		    (stop == psrc + 1 && !(*psrc & sbitmask))
		    ) {
		    /* The input is all 0s.  Clear the row and exit. */
		    INCS(all0s);
		    fill_row(line, line_x, raster, zero);
		    return;
		}
		last = *--stop;
	    }
	    stopx = byte_bit_run_length_0[byte_reverse_bits[last ^ 0xff]] - 1;
	}
	if (stopx < 0)
	    stopx = 7, ++stop;
	stopbit = 1 << stopx;
    }

    /* Pre-clear the row. */
    fill_row(line, line_x, raster, zero);

    /* Set up the DDAs. */
    xl0 =
	(x_extent >= 0 ?
	 fixed_fraction(fixed_pre_pixround(xcur)) :
	 fixed_fraction(fixed_pre_pixround(xcur + x_extent)) - x_extent);
    xl0 += int2fixed(line_x);
    dda_init(xl, xl0, x_extent, w);
    dxx4 = xl.step;
    dda_step_add(dxx4, xl.step);
    /* egcc - 2.91.66 generates incorrect code for
     * dda_step_add(dxx4, dxx4); 
     * Using the temp variable.
     */
    dxx8 = dxx4;
    dda_step_add(dxx4, dxx8);
    dxx8 = dxx4;
    dda_step_add(dxx8, dxx4);
    dxx16 = dxx8;
    dda_step_add(dxx16, dxx8);
    dxx24 = dxx16;
    dda_step_add(dxx24, dxx8);
    dxx32 = dxx24;
    dda_step_add(dxx32, dxx8);

    /*
     * Loop invariants:
     *      data = *psrc;
     *      sbit = 1 << n, 0<=n<=7.
     */
    for (data = *psrc;;) {
	int x0, n, bit;
	byte *bp;
	static const byte lmasks[9] = {
	    0xff, 0x7f, 0x3f, 0x1f, 0xf, 7, 3, 1, 0
	};
	static const byte rmasks[9] = {
	    0, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff
	};

	INCS(runs);

	/* Scan a run of zeros. */
	data ^= 0xff;		/* invert */
	while (data & sbit) {
	    dda_next(xl);
	    sbit >>= 1;
	    INCS(lbit0);
	}
	if (!sbit) {		/* Scan a run of zero bytes. */
sw:	    if ((data = psrc[1]) != 0) {
		psrc++;
		INCS(byte00);
	    } else if ((data = psrc[2]) != 0) {
		dda_state_next(xl.state, dxx8);
		psrc += 2;
		INCS(byte01);
	    } else if ((data = psrc[3]) != 0) {
		dda_state_next(xl.state, dxx16);
		psrc += 3;
		INCS(byte02);
	    } else if ((data = psrc[4]) != 0) {
		dda_state_next(xl.state, dxx24);
		psrc += 4;
		INCS(byte03);
	    } else {
		dda_state_next(xl.state, dxx32);
		psrc += 4;
		INCS(byte04);
		goto sw;
	    }
	    if (data > 0xf)
		sbit = 0x80;
	    else {
		sbit = 0x08;
		dda_state_next(xl.state, dxx4);
	    }
	    data ^= 0xff;	/* invert */
	    while (data & sbit) {
		dda_next(xl);
		sbit >>= 1;
		INCS(rbit0);
	    }
	}
	x0 = dda_current_fixed2int(xl);
	if (psrc >= stop && sbit == stopbit) {
	    /*
	     * We've scanned the last run of 0s.
	     * Prepare to fill the final run of 1s.
	     */
	    n = fixed2int(xl0 + x_extent) - x0;
	} else {		/* Scan a run of ones. */
	    /* We know the current bit is a one. */
	    data ^= 0xff;	/* un-invert */
	    do {
		dda_next(xl);
		sbit >>= 1;
		INCS(lbit1);
	    }
	    while (data & sbit);
	    if (!sbit) {	/* Scan a run of 0xff bytes. */
		while ((data = *++psrc) == 0xff) {
		    dda_state_next(xl.state, dxx8);
		    INCS(byte1);
		}
		if (data < 0xf0)
		    sbit = 0x80;
		else {
		    sbit = 0x08;
		    dda_state_next(xl.state, dxx4);
		}
		while (data & sbit) {
		    dda_next(xl);
		    sbit >>= 1;
		    INCS(rbit1);
		}
	    }
	    n = dda_current_fixed2int(xl) - x0;
	}

	/* Fill the run in the scan line. */
	if (n < 0)
	    x0 += n, n = -n;
	bp = line + (x0 >> 3);
	bit = x0 & 7;
	if ((n += bit) <= 8) {
	    *bp ^= lmasks[bit] - lmasks[n];
	    INCS(thin);
	} else if ((n -= 8) <= 8) {
	    *bp ^= lmasks[bit];
	    bp[1] ^= rmasks[n];
	    INCS(thin2);
	} else {
	    *bp++ ^= lmasks[bit];
	    if (n >= 56) {
		int nb = n >> 3;

		memset(bp, one, nb);
		bp += nb;
		INCS(nwide);
		ADDS(bwide, nb);
	    } else {
		ADDS(bfill, n >> 3);
		while ((n -= 8) >= 0)
		    *bp++ = one;
		INCS(nfill);
	    }
	    *bp ^= rmasks[n & 7];
	}
	if (psrc >= stop && sbit == stopbit)
	    break;
    }
}

/* Copy one rendered scan line to the device. */
private int
copy_portrait(gx_image_enum * penum, const byte * data, int dx, int raster,
	      int x, int y, int w, int h, gx_device * dev)
{
    const gx_device_color *pdc0;
    const gx_device_color *pdc1;
    uint align = ALIGNMENT_MOD(data, align_bitmap_mod);

    /*
     * We know that the lookup table maps 1 bit to 1 bit,
     * so it can only have 2 states: straight-through or invert.
     */
    if (penum->map[0].table.lookup4x1to32[0])
	pdc0 = &penum->icolor1, pdc1 = &penum->icolor0;
    else
	pdc0 = &penum->icolor0, pdc1 = &penum->icolor1;
    data -= align;
    dx += align << 3;
    if (gx_dc_is_pure(pdc0) && gx_dc_is_pure(pdc1)) {
	/* Just use copy_mono. */
	dev_proc_copy_mono((*copy_mono)) =
	    (h == 1 || (raster & (align_bitmap_mod - 1)) == 0 ?
	     dev_proc(dev, copy_mono) : gx_copy_mono_unaligned);
	return (*copy_mono)
	    (dev, data, dx, raster, gx_no_bitmap_id,
	     x, y, w, h, pdc0->colors.pure, pdc1->colors.pure);
    }
    /*
     * At least one color isn't pure: if the other one is transparent, use
     * the opaque color's fill_masked procedure.  Note that we use a
     * slightly unusual representation for transparent here (per
     * gx_begin_image1): a pure color with pixel value gx_no_color_index.
     */
    {
	const gx_device_color *pdc;
	bool invert;

	if (DC_IS_NULL(pdc1)) {
	    pdc = pdc0;
	    invert = true;
	} else {
	    if (!DC_IS_NULL(pdc0)) {
		int code = gx_device_color_fill_rectangle
		    (pdc0, x, y, w, h, dev, lop_default, NULL);

		if (code < 0)
		    return code;
	    }
	    pdc = pdc1;
	    invert = false;
	}
	return (*pdc->type->fill_masked)
	    (pdc, data, dx, raster, gx_no_bitmap_id, x, y, w, h,
	     dev, lop_default, invert);

    }
}

/* Rendering procedure for a monobit image with no */
/* skew or rotation and pure colors. */
private int
image_render_simple(gx_image_enum * penum, const byte * buffer, int data_x,
		    uint w, int h, gx_device * dev)
{
    dev_proc_copy_mono((*copy_mono)) = dev_proc(dev, copy_mono);
    const fixed dxx = penum->dxx;
    const byte *line;
    uint line_width, line_size;
    int line_x;
    fixed xcur = dda_current(penum->dda.pixel0.x);
    int ix = fixed2int_pixround(xcur);
    int ixr;
    const int iy = penum->yci, ih = penum->hci;
    gx_device_color * const pdc0 = &penum->icolor0;
    gx_device_color * const pdc1 = &penum->icolor1;
    int dy;
    int code;

    if (h == 0)
	return 0;
    if ((!DC_IS_NULL(pdc0) &&
	 (code = gx_color_load(pdc0, penum->pis, dev)) < 0) ||
	(!DC_IS_NULL(pdc1) &&
	 (code = gx_color_load(pdc1, penum->pis, dev)) < 0)
	)
	return code;
    if (penum->line == 0) {	/* A direct BitBlt is possible. */
	line = buffer;
	line_size = (w + 7) >> 3;
	line_width = w;
	line_x = 0;
    } else if (copy_mono == dev_proc(&mem_mono_device, copy_mono) &&
	       dxx > 0 && gx_dc_is_pure(pdc1) && gx_dc_is_pure(pdc0) &&
	       /* We know the colors must be (0,1) or (1,0). */
	       (pdc0->colors.pure ^ pdc1->colors.pure) == 1 &&
	       !penum->clip_image &&
	       /*
		* Even if clip_image is false, the clipping rectangle
		* might lie partly outside the device coordinate space
		* if the Margins values are non-zero.
		*/
	       ix >= 0 &&
	       (ixr = fixed2int_pixround(xcur + penum->x_extent.x) - 1) <
	         dev->width &&
	       iy >= 0 && iy + ih <= dev->height
	) {
	/* Do the operation directly into the memory device bitmap. */
	int line_ix;
	int ib_left = ix >> 3, ib_right = ixr >> 3;
	byte *scan_line = scan_line_base((gx_device_memory *) dev, iy);
	byte save_left, save_right, mask;

	line_x = ix & (align_bitmap_mod * 8 - 1);
	line_ix = ix - line_x;
	line_size = (ixr >> 3) + 1 - (line_ix >> 3);
	line_width = ixr + 1 - ix;
	/* We must save and restore any unmodified bits in */
	/* the two edge bytes. */
	save_left = scan_line[ib_left];
	save_right = scan_line[ib_right];
	image_simple_expand(scan_line + (line_ix >> 3), line_x,
			    line_size, buffer, data_x, w, xcur,
			    penum->x_extent.x,
			    ((pdc0->colors.pure == 0) !=
			     (penum->map[0].table.lookup4x1to32[0] == 0) ?
			     0xff : 0));
	if (ix & 7)
	    mask = (byte) (0xff00 >> (ix & 7)),
		scan_line[ib_left] =
		(save_left & mask) + (scan_line[ib_left] & ~mask);
	if ((ixr + 1) & 7)
	    mask = (byte) (0xff00 >> ((ixr + 1) & 7)),
		scan_line[ib_right] =
		(scan_line[ib_right] & mask) + (save_right & ~mask);
	if (ih <= 1)
	    return 1;
	/****** MAY BE UNALIGNED ******/
	line = scan_line + (line_ix >> 3);
	if (dxx < 0)
	    ix -= line_width;
	for (dy = 1; dy < ih; dy++) {
	    int code = (*copy_mono)
		(dev, line, line_x, line_size, gx_no_bitmap_id,
		 ix, iy + dy, line_width, 1,
		 (gx_color_index)0, (gx_color_index)1);

	    if (code < 0)
		return code;
	}
	return 0;
    } else {
	line = penum->line;
	line_size = penum->line_size;
	line_width = penum->line_width;
	line_x = ix & (align_bitmap_mod * 8 - 1);
	image_simple_expand(penum->line, line_x, line_size,
			    buffer, data_x, w, xcur,
			    penum->x_extent.x, 0);
    }

    /* Finally, transfer the scan line to the device. */
    if (dxx < 0)
	ix -= line_width;
    for (dy = 0; dy < ih; dy++) {
	int code = copy_portrait(penum, line, line_x, line_size,
				 ix, iy + dy, line_width, 1, dev);

	if (code < 0)
	    return code;
    }

    return 1;
}

/* Rendering procedure for a 90 degree rotated monobit image */
/* with pure colors.  We buffer and then flip 8 scan lines at a time. */
private int copy_landscape(P5(gx_image_enum *, int, int, bool, gx_device *));
private int
image_render_landscape(gx_image_enum * penum, const byte * buffer, int data_x,
		       uint w, int h, gx_device * dev)
{
    byte *line = penum->line;
    uint raster = bitmap_raster(penum->line_width);
    int ix = penum->xci, iw = penum->wci;
    int xinc, xmod;
    byte *row;
    const byte *orig_row = 0;
    bool y_neg = penum->dxy < 0;

    if (is_fneg(penum->matrix.yx))
	ix += iw, iw = -iw, xinc = -1;
    else
	xinc = 1;
    /*
     * Because of clipping, there may be discontinuous jumps in the values
     * of ix (xci).  If this happens, or if we are at the end of the data or
     * a client has requested flushing, flush the flipping buffer.
     */
    if (ix != penum->xi_next || h == 0) {
	int xi = penum->xi_next;
	int code =
	    (xinc > 0 ?
	     copy_landscape(penum, penum->line_xy, xi, y_neg, dev) :
	     copy_landscape(penum, xi, penum->line_xy, y_neg, dev));

	if (code < 0)
	    return code;
	penum->line_xy = penum->xi_next = ix;
	if (h == 0)
	    return code;
    }
    for (; iw != 0; iw -= xinc) {
	if (xinc < 0)
	    --ix;
	xmod = ix & 7;
	row = line + xmod * raster;
	if (orig_row == 0) {
	    image_simple_expand(row, 0, raster,
				buffer, data_x, w,
				dda_current(penum->dda.pixel0.y),
				penum->x_extent.y, 0);
	    orig_row = row;
	} else
	    memcpy(row, orig_row, raster);
	if (xinc > 0) {
	    ++ix;
	    if (xmod == 7) {
		int code =
		    copy_landscape(penum, penum->line_xy, ix, y_neg, dev);

		if (code < 0)
		    return code;
		orig_row = 0;
		penum->line_xy = ix;
	    }
	} else {
	    if (xmod == 0) {
		int code =
		    copy_landscape(penum, ix, penum->line_xy, y_neg, dev);

		if (code < 0)
		    return code;
		orig_row = 0;
		penum->line_xy = ix;
	    }
	}
    }
    penum->xi_next = ix;
    return 0;
}

/* Flip and copy one group of scan lines. */
private int
copy_landscape(gx_image_enum * penum, int x0, int x1, bool y_neg,
	       gx_device * dev)
{
    byte *line = penum->line;
    uint line_width = penum->line_width;
    uint raster = bitmap_raster(line_width);
    byte *flipped = line + raster * 8;
    int w = x1 - x0;
    int y = fixed2int_pixround(dda_current(penum->dda.pixel0.y));

    if (w == 0 || line_width == 0)
	return 0;
    /* Flip the buffered data from raster x 8 to align_bitmap_mod x */
    /* line_width. */
    if (line_width > 0) {
	int i;

	for (i = (line_width - 1) >> 3; i >= 0; --i)
	    memflip8x8(line + i, raster,
		       flipped + (i << (log2_align_bitmap_mod + 3)),
		       align_bitmap_mod);
    }
    /* Transfer the scan lines to the device. */
    if (w < 0)
	x0 = x1, w = -w;
    if (y_neg)
	y -= line_width;
    return copy_portrait(penum, flipped, x0 & 7, align_bitmap_mod,
			 x0, y, w, line_width, dev);
}