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/* See LICENSE file for copyright and license details. */
#include "common.h"
enum libsyscalls_error
libsyscalls_parse_signed_integer(unsigned long long int value_in, enum libsyscalls_datatype_sign_representation representation,
size_t bits, unsigned long long int *value_out, int *negative_out)
{
unsigned long long int value = value_in, mask;
int negative = 0;
if (!bits || bits > sizeof(value) / sizeof(char) * CHAR_BIT)
return LIBSYSCALLS_E_INVAL;
switch (representation) {
case LIBSYSCALLS_SIGN_UNDETERMINED:
break;
case LIBSYSCALLS_SIGN_TWOS_COMPLEMENT:
if (value >> (bits - 1U)) {
mask = (1ULL << (bits - 1U)) - 1ULL;
value = ~value & mask;
value += 1ULL;
negative = 1;
}
break;
case LIBSYSCALLS_SIGN_ONES_COMPLEMENT:
if (value >> (bits - 1U)) {
mask = (1ULL << (bits - 1U)) - 1ULL;
value = ~value & mask;
negative = 1;
}
break;
case LIBSYSCALLS_SIGN_SIGN_MAGNITUDE:
if (value >> (bits - 1U)) {
value ^= 1ULL << (bits - 1U);
negative = 1;
}
break;
case LIBSYSCALLS_SIGN_EXCESS_HALF:
if (value >> (bits - 1U)) {
value ^= 1ULL << (bits - 1U);
} else {
value = (1ULL << (bits - 1U)) - value;
negative = 1;
}
break;
default:
return LIBSYSCALLS_E_INVAL;
}
if (value_out)
*value_out = value;
if (negative_out)
*negative_out = negative;
return LIBSYSCALLS_E_OK;
}
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