mirrors/yosys
3
0
Fork 0
mirror of https://github.com/YosysHQ/yosys synced 2025-04-22 16:45:32 +00:00
Code Activity

Added "int ceil_log2(int)" function

Browse source
This commit is contained in:
Clifford Wolf 2016-02-13 16:52:16 +01:00
parent a75f94ec4a
commit 0d7fd2585e
5 changed files with 58 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

24
libs/ezsat/ezsat.cc
View file

@ -1337,6 +1337,28 @@ void ezSAT::printInternalState(FILE *f) const
fprintf(f, "--8<-- snap --8<--\n");
}
static int clog2(int x)
{
int y = (x & (x - 1));
y = (y | -y) >> 31;
x |= (x >> 1);
x |= (x >> 2);
x |= (x >> 4);
x |= (x >> 8);
x |= (x >> 16);
x >>= 1;
x -= ((x >> 1) & 0x55555555);
x = (((x >> 2) & 0x33333333) + (x & 0x33333333));
x = (((x >> 4) + x) & 0x0f0f0f0f);
x += (x >> 8);
x += (x >> 16);
x = x & 0x0000003f;
return x - y;
}
int ezSAT::onehot(const std::vector<int> &vec, bool max_only)
{
// Mixed one-hot/binary encoding as described by Claessen in Sec. 4.2 of
@ -1350,7 +1372,7 @@ int ezSAT::onehot(const std::vector<int> &vec, bool max_only)
formula.push_back(expression(OpOr, vec));
// create binary vector
int num_bits = ceil(log2(vec.size()));
int num_bits = clog2(vec.size());
std::vector<int> bits;
for (int k = 0; k < num_bits; k++)
bits.push_back(literal());