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uint128: Check for large shift count before truncating in << and >>

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- Correctly handle very large shift counts
- uint128(1) << (uint64_t(1) << 32) should now be 0 as expected
This commit is contained in:
theoretical 2015-01-30 12:54:30 -05:00
parent ac197311ca
commit 4b8c211629
1 changed files with 9 additions and 8 deletions
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15
src/uint128.cpp
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@ -150,15 +150,14 @@ namespace fc
uint128& uint128::operator<<=(const uint128& rhs) uint128& uint128::operator<<=(const uint128& rhs)
{ {
unsigned int n = rhs.to_integer(); if(rhs >= 128)
if(n >= 128)
{ {
hi = 0; hi = 0;
lo = 0; lo = 0;
} }
else else
{ {
unsigned int n = rhs.to_integer();
const unsigned int halfsize = 128 / 2; const unsigned int halfsize = 128 / 2;
if(n >= halfsize){ if(n >= halfsize){
@ -186,12 +185,14 @@ namespace fc
uint128 & uint128::operator>>=(const uint128& rhs) uint128 & uint128::operator>>=(const uint128& rhs)
{ {
unsigned int n = rhs.to_integer(); if(rhs >= 128)
{
if(n >= 128) {
hi = 0; hi = 0;
lo = 0; lo = 0;
} else { }
else
{
unsigned int n = rhs.to_integer();
const unsigned int halfsize = 128 / 2; const unsigned int halfsize = 128 / 2;
if(n >= halfsize) { if(n >= halfsize) {