From 45af4a4acf6d3bc1f83b65f1cd103c0226f30b8b Mon Sep 17 00:00:00 2001 From: Clifford Wolf Date: Mon, 15 Feb 2016 23:06:18 +0100 Subject: [PATCH] Use easyer-to-read unoptimized ceil_log2() see here for details on the optimized version: http://svn.clifford.at/handicraft/2016/esbmc/ceilog2.c --- kernel/yosys.cc | 23 +++++------------------ 1 file changed, 5 insertions(+), 18 deletions(-) diff --git a/kernel/yosys.cc b/kernel/yosys.cc index 8590242dc..eba1aef11 100644 --- a/kernel/yosys.cc +++ b/kernel/yosys.cc @@ -129,24 +129,11 @@ int ceil_log2(int x) if (x <= 0) return 0; - 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; + for (int i = 0; i < 32; i++) + if (((x-1) >> i) == 0) + return i; + + log_abort(); } std::string stringf(const char *fmt, ...) -- 2.30.2