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crypto: make bn_format faster

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This commit is contained in:
Ondřej Vejpustek 2020-06-01 18:21:24 +02:00
parent 015c294857
commit 9598d17f10
1 changed files with 23 additions and 8 deletions
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31
crypto/bignum.c
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@ -1715,23 +1715,33 @@ size_t bn_format(const bignum256 *amount, const char *prefix, const char *suffix
BN_FORMAT_ADD_OUTPUT_CHAR(suffix[i])
// amount //= 10**exponent
if (exponent < 0) {
for (; exponent < 0; ++exponent) {
bn_divmod10(&temp, &digit);
for (; exponent < 0; ++exponent) {
// if temp == 0, there is no need to divide it by 10 anymore
if (bn_is_zero(&temp)) {
exponent = 0;
break;
}
bn_divmod10(&temp, &digit);
}
// exponent >= 0 && decimals >= 0
bool fractional_part = false; // is fractional-part of amount present
{ // Add fractional-part digits of amount
// Add trailing zeroes
for (; exponent > 0 && decimals > 0; --exponent, --decimals) {
if (trailing) {
BN_FORMAT_ADD_OUTPUT_CHAR('0')
fractional_part = true;
}
unsigned int trailing_zeros = decimals < (unsigned int) exponent ? decimals : (unsigned int) exponent;
// When casting a negative int to unsigned int, UINT_MAX is added to the int before
// Since exponent >= 0, the value remains unchanged
decimals -= trailing_zeros;
exponent -= trailing_zeros;
if (trailing && trailing_zeros) {
fractional_part = true;
for (; trailing_zeros > 0; --trailing_zeros)
BN_FORMAT_ADD_OUTPUT_CHAR('0')
}
// exponent == 0 || decimals == 0
// Add significant digits and leading zeroes
@ -1742,6 +1752,11 @@ size_t bn_format(const bignum256 *amount, const char *prefix, const char *suffix
fractional_part = true;
BN_FORMAT_ADD_OUTPUT_CHAR('0' + digit)
}
else if (bn_is_zero(&temp)) {
// We break since the remaining digits are zeroes and fractional_part == trailing == false
decimals = 0;
break;
}
}
// decimals == 0
}