/* Lab2LabQ: quantise FLOAT Lab image into 10 11 11 format
 *
 * 4 bytes per pel: l a b lsbs
 * this is an image wrapper which calls line-wise packing
 * Copyright K.Martinez 3/5/93
 * Modified:
 * 7/6/93 JC
 *	- adapted for partial v2
 * 5/5/94 JC
 *	- some nint->+0.5, for speed and to ease portability
 *	- other nint->rint
 *	- now includes <math.h>!
 * 15/11/94 JC
 *	- all nint(), rint() removed for speed
 *	- now -128 rather than -127 for a, b
 *	- checks input type properly
 * 16/11/94 JC
 *	- uses new im_wrap_oneonebuf()
 * 22/5/95 JC
 *	- changed L to scale by 10.24, not 10.23
 * 11/7/95 JC
 *	- now uses IM_RINT() for rounding
 * 4/9/97 JC
 *	- L* = 100.0 now allowed
 * 5/11/00 JC
 *	- go int earlier for speed up
 * 20/6/02 JC
 *	- oops, were not clipping a/b range correctly
 * 1/11/09
 *	- gtkdoc
 *	- cleanups
 * 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 <math.h>

#include <vips/vips.h>

#include "pcolour.h"

typedef VipsColourCode VipsLab2LabQ;
typedef VipsColourCodeClass VipsLab2LabQClass;

G_DEFINE_TYPE(VipsLab2LabQ, vips_Lab2LabQ, VIPS_TYPE_COLOUR_CODE);

/* @(#) convert float Lab to packed Lab32 format 10 11 11 bits
 * works only on buffers, not IMAGEs
 * Copyright 1993 K.Martinez
 * Modified: 3/5/93, 16/6/93
 */
static void
vips_Lab2LabQ_line(VipsColour *colour, VipsPel *out, VipsPel **in, int width)
{
	float *restrict p = (float *) in[0];
	VipsPel *restrict q = out;

	int i;

	for (i = 0; i < width; i++) {
		float fval;
		int lsbs;
		int intv;

		/* Scale L up to 10 bits.
		 */
		intv = VIPS_ROUND_UINT(10.23 * p[0]);
		intv = VIPS_CLIP(0, intv, 1023);
		lsbs = (intv & 0x3) << 6; /* 00000011 -> 11000000 */
		q[0] = intv >> 2;		  /* drop bot 2 bits and store */

		fval = 8.0 * p[1]; /* do a */
		intv = VIPS_RINT(fval);
		intv = VIPS_CLIP(-1024, intv, 1023);
		lsbs |= (intv & 0x7) << 3; /* 00000111 -> 00111000 */
		q[1] = intv >> 3;		   /* drop bot 3 bits & store */

		fval = 8.0 * p[2]; /* do b */
		intv = VIPS_RINT(fval);
		intv = VIPS_CLIP(-1024, intv, 1023);
		lsbs |= (intv & 0x7);
		q[2] = intv >> 3;

		q[3] = lsbs; /* store lsb band */

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

void
vips__Lab2LabQ_vec(VipsPel *out, float *in, int width)
{
	vips_Lab2LabQ_line(NULL, out, (VipsPel **) &in, width);
}

static void
vips_Lab2LabQ_class_init(VipsLab2LabQClass *class)
{
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsColourClass *colour_class = VIPS_COLOUR_CLASS(class);

	object_class->nickname = "Lab2LabQ";
	object_class->description = _("transform float Lab to LabQ coding");

	colour_class->process_line = vips_Lab2LabQ_line;
}

static void
vips_Lab2LabQ_init(VipsLab2LabQ *Lab2LabQ)
{
	VipsColour *colour = VIPS_COLOUR(Lab2LabQ);
	VipsColourCode *code = VIPS_COLOUR_CODE(Lab2LabQ);

	colour->coding = VIPS_CODING_LABQ;
	colour->interpretation = VIPS_INTERPRETATION_LABQ;
	colour->format = VIPS_FORMAT_UCHAR;
	colour->input_bands = 3;
	colour->bands = 4;

	code->input_coding = VIPS_CODING_NONE;
	code->input_format = VIPS_FORMAT_FLOAT;
}

/**
 * vips_Lab2LabQ: (method)
 * @in: input image
 * @out: (out): output image
 * @...: %NULL-terminated list of optional named arguments
 *
 * Convert a Lab three-band float image to LabQ (#VIPS_CODING_LABQ).
 *
 * See also: vips_LabQ2Lab().
 *
 * Returns: 0 on success, -1 on error.
 */
int
vips_Lab2LabQ(VipsImage *in, VipsImage **out, ...)
{
	va_list ap;
	int result;

	va_start(ap, out);
	result = vips_call_split("Lab2LabQ", ap, in, out);
	va_end(ap);

	return result;
}
