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math.big: fix Integer.bit_len() when there are no digits in the number

master
Delyan Angelov 2022-05-18 08:29:08 +03:00
parent ebac3bebb1
commit ed17779434
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2 changed files with 10 additions and 5 deletions
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11
vlib/math/big/big_test.v
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@ -433,7 +433,7 @@ fn test_set_bit() {
assert a == b assert a == b
} }
fn test_bit_len() { fn test_bit_len() ? {
assert big.zero_int.bit_len() == 0 assert big.zero_int.bit_len() == 0
assert big.one_int.bit_len() == 1 assert big.one_int.bit_len() == 1
@ -441,7 +441,10 @@ fn test_bit_len() {
assert big.one_int.lshift(1239).bit_len() == 1240 assert big.one_int.lshift(1239).bit_len() == 1240
assert big.integer_from_string('4338476092346017364013796407961305761039463198075691378460917856') or { mut num := big.integer_from_string('4338476092346017364013796407961305761039463198075691378460917856')?
panic('Could not read from decimal') assert num.bit_len() == 212
}.bit_len() == 212 for num.bit_len() > 0 {
num = num.rshift(8)
assert true
}
} }

4
vlib/math/big/integer.v
View File

@ -960,6 +960,8 @@ pub fn (x Integer) bit_len() int {
if x.signum == 0 { if x.signum == 0 {
return 0 return 0
} }
if x.digits.len == 0 {
return 0
}
return x.digits.len * 32 - bits.leading_zeros_32(x.digits.last()) return x.digits.len * 32 - bits.leading_zeros_32(x.digits.last())
} }