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Added a signed int256 formatting function

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This commit is contained in:
Alexandre Paillier
2022-06-06 18:36:20 +02:00
parent 59d8ace99e
commit f99804de08
4 changed files with 87 additions and 0 deletions
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39
src_common/uint256.c
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@@ -248,3 +248,42 @@ bool tostring256(const uint256_t *const number,
reverseString(out, offset);
return true;
}
/**
* Format a uint256_t into a string as a signed integer
*
* @param[in] number the number to format
* @param[in] base the radix used in formatting
* @param[out] out the output buffer
* @param[in] out_length the length of the output buffer
* @return whether the formatting was successful or not
*/
bool tostring256_signed(const uint256_t *const number,
uint32_t base,
char *const out,
uint32_t out_length) {
uint256_t max_unsigned_val;
uint256_t max_signed_val;
uint256_t one_val;
uint256_t two_val;
uint256_t tmp;
// showing negative numbers only really makes sense in base 10
if (base == 10) {
explicit_bzero(&one_val, sizeof(one_val));
LOWER(LOWER(one_val)) = 1;
explicit_bzero(&two_val, sizeof(two_val));
LOWER(LOWER(two_val)) = 2;
memset(&max_unsigned_val, 0xFF, sizeof(max_unsigned_val));
divmod256(&max_unsigned_val, &two_val, &max_signed_val, &tmp);
if (gt256(number, &max_signed_val)) // negative value
{
sub256(&max_unsigned_val, number, &tmp);
add256(&tmp, &one_val, &tmp);
out[0] = '-';
return tostring256(&tmp, base, out + 1, out_length - 1);
}
}
return tostring256(number, base, out, out_length); // positive value
}