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/* See LICENSE file for copyright and license details. */
#include "common.h"
/**
* Convert an hexadecimal representation of an EDID to a raw representation
*
* @param edid The EDID in hexadecimal representation
* @return The EDID in raw representation, it will be half the length
* of `edid` (the input value); `NULL` on allocation error or
* if the EDID is malformated, `errno` will be set accordingly
*/
unsigned char *
libgamma_unhex_edid(const char *restrict edid)
{
unsigned char *restrict out;
size_t i, n = strlen(edid);
char a, b;
/* Check that the length of the strings is even,
* otherwise it cannot represent bytes */
if (n & 1) {
errno = EINVAL;
return NULL;
}
/* Allocate memory area for output octet array */
n /= 2 * sizeof(unsigned char);
out = malloc(n);
if (!out)
return NULL;
/* Convert to raw octet array */
for (i = 0; i < n; i++) {
/* Get the next character pair that, it represents an octet. */
a = edid[i * 2 + 0];
b = edid[i * 2 + 1];
/* Verify that the input is in hexadecimal */
if (!isxdigit(a) || !isxdigit(b)) {
free(out);
errno = EINVAL;
return NULL;
}
/* Convert each chararacter to raw format */
a = (char)((a & 15) + (a > '9' ? 9 : 0));
b = (char)((b & 15) + (b > '9' ? 9 : 0));
/* Combine the two characters into one octet */
out[i] = (unsigned char)((a << 4) | b);
}
return out;
}
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