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/**
* Copyright © 2016 Mattias Andrée <maandree@member.fsf.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 3 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 <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <unistd.h>
#include <math.h>
#include <sys/stat.h>
#define HIGHEST 40000
#define LOWEST 1000
#define DELTA 100
#define EXPECTED_ELEMENTS ((HIGHEST - LOWEST) / DELTA + 1)
static void
ciexyy_to_srgb(double x, double y, double Y, double *r, double *g, double *b)
{
#define SRGB(C) (((C) <= 0.0031308) ? (12.92 * (C)) : ((1.0 + 0.055) * pow((C), 1.0 / 2.4) - 0.055))
double X, Z;
/* Convert CIE xyY to CIE XYZ. */
X = Y * (y == 0 ? 0 : (x / y));
Z = Y * (y == 0 ? 0 : ((1 - x - y) / y));
/* Convert CIE XYZ to [0, 1] linear RGB. (ciexyz_to_linear) */
*r = ( 3.240450 * X) + (-1.537140 * Y) + (-0.4985320 * Z);
*g = (-0.969266 * X) + ( 1.876010 * Y) + ( 0.0415561 * Z);
*b = (0.0556434 * X) + (-0.204026 * Y) + ( 1.0572300 * Z);
/* Convert [0, 1] linear RGB to [0, 1] sRGB. */
SRGB(*r), SRGB(*g), SRGB(*b);
}
int main(void)
{
double xyrgb[5];
struct stat attr;
while (fscanf(stdin, "%lf %lf\n", xyrgb + 0, xyrgb + 1) == 2) {
ciexyy_to_srgb(xyrgb[0], xyrgb[1], 1.0, xyrgb + 2, xyrgb + 3, xyrgb + 4);
if (write(1, xyrgb, sizeof(xyrgb)) < (ssize_t)sizeof(xyrgb))
return perror(""), 1;
}
if (write(1, xyrgb, sizeof(xyrgb)) < (ssize_t)sizeof(xyrgb)) /* sugar */
return perror(""), 1;
if (fstat(1, &attr))
return perror(""), 1;
if ((size_t)(attr.st_size) != (EXPECTED_ELEMENTS + 1) * 5 * sizeof(double))
return 1;
return 0;
}
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