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Use easyer-to-read unoptimized ceil_log2() 

see here for details on the optimized version:
http://svn.clifford.at/handicraft/2016/esbmc/ceilog2.c
This commit is contained in:
Clifford Wolf 2016-02-15 23:06:18 +01:00
parent 7a9257e7b5
commit 45af4a4acf
1 changed files with 4 additions and 17 deletions
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21
kernel/yosys.cc
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@ -129,24 +129,11 @@ int ceil_log2(int x)
if (x <= 0) if (x <= 0)
return 0; return 0;
int y = (x & (x - 1)); for (int i = 0; i < 32; i++)
y = (y | -y) >> 31; if (((x-1) >> i) == 0)
return i;
x |= (x >> 1); log_abort();
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;
} }
std::string stringf(const char *fmt, ...) std::string stringf(const char *fmt, ...)