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Update libraries.rst

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add unchecked
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GuLiPing-Hz 2021-07-22 18:37:08 +08:00 committed by hrkrshnn
parent 6d6c9e6e4f
commit 997c014971
1 changed files with 9 additions and 6 deletions
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15
docs/contracts/libraries.rst
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@ -132,7 +132,7 @@ custom types without the overhead of external function calls:
.. code-block:: solidity .. code-block:: solidity
// SPDX-License-Identifier: GPL-3.0 // SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.6.8 <0.9.0; pragma solidity >=0.8.0 <0.9.0;
struct bigint { struct bigint {
uint[] limbs; uint[] limbs;
@ -150,11 +150,14 @@ custom types without the overhead of external function calls:
for (uint i = 0; i < r.limbs.length; ++i) { for (uint i = 0; i < r.limbs.length; ++i) {
uint a = limb(_a, i); uint a = limb(_a, i);
uint b = limb(_b, i); uint b = limb(_b, i);
r.limbs[i] = a + b + carry; unchecked {
if (a + b < a || (a + b == type(uint).max && carry > 0)) r.limbs[i] = a + b + carry;
carry = 1;
else if (a + b < a || (a + b == type(uint).max && carry > 0))
carry = 0; carry = 1;
else
carry = 0;
}
} }
if (carry > 0) { if (carry > 0) {
// too bad, we have to add a limb // too bad, we have to add a limb