/* LabQ2Lab
 *
 * Copyright Kirk Martinez 2/5/1993
 *
 * Modified: 16/6/93
 * 7/6/93 JC
 *	- adapted for partial v2
 * 16/11/94 JC
 *	- adapted to new im_wrap_oneonebuf() function.
 * 9/2/95 JC
 *	- new im_wrapone function
 * 22/5/95 JC
 *	- changed char to unsigned char for RS/6000
 * 	- small tidies and speed-ups
 * 4/9/97 JC
 *	- L* = 100.0 now handled correctly
 * 2/11/09
 * 	- gtkdoc
 * 20/9/12
 * 	- redo as a class
 */

/*

	This file is part of VIPS.

	VIPS is free software; you can redistribute it and/or modify
	it under the terms of the GNU Lesser 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 Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
	02110-1301  USA

 */

/*

	These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk

 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>

#include <stdio.h>

#include <vips/vips.h>
#include <vips/internal.h>

#include "pcolour.h"

typedef VipsColourCode VipsLabQ2Lab;
typedef VipsColourCodeClass VipsLabQ2LabClass;

G_DEFINE_TYPE(VipsLabQ2Lab, vips_LabQ2Lab, VIPS_TYPE_COLOUR_CODE);

/* imb_LabQ2Lab: CONVERT n pels from packed 32bit Lab to float values
 * in a buffer
 * ARGS:   VipsPel *inp       pointer to first byte of Lab32 buffer
 * float *outbuf   destination buffer
 *	int n           number of pels to process
 * (C) K.Martinez 2/5/93
 */
static void
vips_LabQ2Lab_line(VipsColour *colour, VipsPel *out, VipsPel **in, int width)
{
	signed char *restrict p = (signed char *) in[0];
	float *restrict q = (float *) out;

	int l;
	int lsbs; /* for lsbs byte */
	int i;	  /* counter      */

	/* Read input with a signed pointer to get signed ab easily.
	 */
	for (i = 0; i < width; i++) {
		/* Get extra bits.
		 */
		lsbs = ((unsigned char *) p)[3];

		/* Build L.
		 */
		l = ((unsigned char *) p)[0];
		l = (l << 2) | (lsbs >> 6);
		q[0] = (float) l * (100.0 / 1023.0);

		/* Build a.
		 */
		l = VIPS_LSHIFT_INT(p[1], 3) | ((lsbs >> 3) & 0x7);
		q[1] = (float) l * 0.125;

		/* And b.
		 */
		l = VIPS_LSHIFT_INT(p[2], 3) | (lsbs & 0x7);
		q[2] = (float) l * 0.125;

		p += 4;
		q += 3;
	}
}

void
vips__LabQ2Lab_vec(float *out, VipsPel *in, int width)
{
	vips_LabQ2Lab_line(NULL, (VipsPel *) out, &in, width);
}

static void
vips_LabQ2Lab_class_init(VipsLabQ2LabClass *class)
{
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsColourClass *colour_class = VIPS_COLOUR_CLASS(class);

	object_class->nickname = "LabQ2Lab";
	object_class->description = _("unpack a LabQ image to float Lab");

	colour_class->process_line = vips_LabQ2Lab_line;
}

static void
vips_LabQ2Lab_init(VipsLabQ2Lab *LabQ2Lab)
{
	VipsColour *colour = VIPS_COLOUR(LabQ2Lab);
	VipsColourCode *code = VIPS_COLOUR_CODE(LabQ2Lab);

	colour->coding = VIPS_CODING_NONE;
	colour->interpretation = VIPS_INTERPRETATION_LAB;
	colour->format = VIPS_FORMAT_FLOAT;
	colour->bands = 3;

	code->input_coding = VIPS_CODING_LABQ;
}

/**
 * vips_LabQ2Lab: (method)
 * @in: input image
 * @out: (out): output image
 * @...: %NULL-terminated list of optional named arguments
 *
 * Unpack a LabQ (#VIPS_CODING_LABQ) image to a three-band float image.
 *
 * See also: vips_LabQ2Lab(), vips_LabQ2LabS(), vips_rad2float().
 *
 * Returns: 0 on success, -1 on error.
 */
int
vips_LabQ2Lab(VipsImage *in, VipsImage **out, ...)
{
	va_list ap;
	int result;

	va_start(ap, out);
	result = vips_call_split("LabQ2Lab", ap, in, out);
	va_end(ap);

	return result;
}
