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/**
* libgamma — Display server abstraction layer for gamma ramp adjustments
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* This library 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 library 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 library. If not, see <http://www.gnu.org/licenses/>.
*/
#include "edid.h"
#include "libgamma-method.h"
#include "libgamma-error.h"
#include <stdint.h>
/**
* Parse the EDID of a monitor.
*
* @param this Instance of a data structure to fill with the information about the EDID.
* It must contain the EDID and its length.
* @param feilds OR:ed identifiers for the information about the EDID that should be parsed.
* Fields that do not have to do with EDID are ignored.
* @return Non-zero on error.
*/
int libgamma_parse_edid(libgamma_crtc_information_t* restrict this, int32_t fields)
{
#define __test_version(edid, major, minor) (((edid)[18] == major) && ((edid)[19] == minor))
int error = 0;
int checksum = 0;
size_t i;
if (this->edid_length != 128)
error = LIBGAMMA_EDID_LENGTH_UNSUPPORTED;
else if ((this->edid[0] != 0x00) || (this->edid[1] != 0xFF) || (this->edid[2] != 0xFF) || (this->edid[3] != 0xFF) ||
(this->edid[4] != 0xFF) || (this->edid[5] != 0xFF) || (this->edid[6] != 0xFF) || (this->edid[7] != 0x00))
error = LIBGAMMA_EDID_WRONG_MAGIC_NUMBER;
else if (__test_version(this->edid, 1, 3) == 0)
error = LIBGAMMA_EDID_REVISION_UNSUPPORTED;
this->width_mm_edid_error = this->height_mm_edid_error = this->gamma_error = error;
this->width_mm_edid = (size_t)(this->edid[21]) * 10;
this->height_mm_edid = (size_t)(this->edid[22]) * 10;
if ((fields & CRTC_INFO_GAMMA) && (error == 0))
{
if (this->edid[23] == 0xFF)
this->gamma_error = LIBGAMMA_GAMMA_NOT_SPECIFIED;
else
this->gamma_red = this->gamma_green = this->gamma_blue = (float)((int)(this->edid[23]) + 100) / 100.f;
}
if (error == 0)
for (i = 0; i < this->edid_length; i++)
checksum += (int)(this->edid[i]);
if ((checksum & 255))
{
error = LIBGAMMA_EDID_CHECKSUM_ERROR;
this->edid_error = this->width_mm_edid_error = this->height_mm_edid_error = error;
this->gamma_error = this->gamma_error == LIBGAMMA_GAMMA_NOT_SPECIFIED
? LIBGAMMA_GAMMA_NOT_SPECIFIED_AND_EDID_CHECKSUM_ERROR : 0;
}
return error | this->gamma_error;
#undef __test_version
}
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