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Diffstat (limited to 'common/kernel/bits.cc')
-rw-r--r-- | common/kernel/bits.cc | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/common/kernel/bits.cc b/common/kernel/bits.cc new file mode 100644 index 00000000..b20c2e86 --- /dev/null +++ b/common/kernel/bits.cc @@ -0,0 +1,56 @@ +/* + * nextpnr -- Next Generation Place and Route + * + * Copyright (c) 2013 Mike Pedersen + * Copyright (C) 2021 Symbiflow Authors + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + * + */ + +#include "bits.h" + +#include <limits> +#include <stdexcept> + +#include "log.h" + +NEXTPNR_NAMESPACE_BEGIN + +int Bits::generic_popcount(unsigned int v) +{ + unsigned int c; // c accumulates the total bits set in v + for (c = 0; v; c++) { + v &= v - 1; // clear the least significant bit set + } + + return c; +} + +int Bits::generic_ctz(unsigned int x) +{ + if (x == 0) { + log_error("Cannot call ctz with arg = 0"); + } + + for (size_t i = 0; i < std::numeric_limits<unsigned int>::digits; ++i) { + if ((x & (1 << i)) != 0) { + return i; + } + } + + // Unreachable! + log_error("Unreachable!"); +} + +NEXTPNR_NAMESPACE_END |