TEST(BitopsTest, findFirst1) {
std::bitset<64> bitset(1);
for (int i = 0; i < 63; i++) {
size_t out = findFirst1(bitset);
EXPECT_EQ(i, out);
out = findFirst1(bitset, i, bitset.size());
EXPECT_EQ(i, out);
out = findFirst1(bitset, i+1, bitset.size());
EXPECT_EQ(bitset.size(), out);
bitset <<= 1;
}
}
TEST(BitopsTest, cornercase) {
std::bitset<64> bitset;
bitset.set(0);
size_t out = findLast1(bitset, 0, 1);
EXPECT_EQ(0, out);
out = findFirst0(bitset, 0, 0);
EXPECT_EQ(0, out);
out = findFirst1(bitset, 1, 1);
EXPECT_EQ(1, out);
out = findLast0(bitset, 2, 2);
EXPECT_EQ(2, out);
}
int squareMultiply(int number,int exp,int mod)
{
int i,retval,first1;
first1=findFirst1(exp);
if(DEBUG)
printf("Num=%d\tExp=%d\tMod=%d\tfirst1=%d\r\n",number,exp,mod,first1);
retval=number;//the first bit
for(i=first1-1;i>=0;i--)//the rest of the bits
{
retval = (int)pow(retval,2);//always square
retval%=mod;
if(DEBUG)
printf("AfterSquare=%d\r\n",retval);
if((exp&(1<<i)) > 0)//only multiply if the bit is a 1
{
retval*=number;
retval%=mod;
if(DEBUG)
printf("AfterMultiply=%d\r\n",retval);
}
}
return retval;
}
