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https://github.com/Z3Prover/z3
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133 lines
2.8 KiB
C
133 lines
2.8 KiB
C
/*++
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Copyright (c) 2012 Microsoft Corporation
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Module Name:
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bit_util.h
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Abstract:
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Bit hacking utilities.
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Author:
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Leonardo de Moura (leonardo) 2012-09-11.
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Revision History:
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--*/
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#ifndef _BIT_UTIL_H_
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#define _BIT_UTIL_H_
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/**
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\brief Return the position of the most significant (set) bit of a
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nonzero unsigned integer.
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*/
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unsigned msb_pos(unsigned v);
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/**
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\brief Return the number of leading zeros bits in a nonzero unsigned integer.
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*/
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unsigned nlz_core(unsigned x);
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/**
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\brief Return the number of leading zero bits in data (a number of sz words).
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*/
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unsigned nlz(unsigned sz, unsigned const * data);
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/**
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\brief Return the number of trailing zeros in a nonzero unsigned number.
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*/
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unsigned ntz_core(unsigned x);
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/**
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\brief Return the number of trailing zero bits in data (a number of sz words).
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*/
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unsigned ntz(unsigned sz, unsigned const * data);
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/**
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\brief dst <- src
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Trucate if src_sz > dst_sz.
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Fill range [src_sz, dst_sz) of dst with zeros if dst_sz > src_sz.
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*/
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void copy(unsigned src_sz, unsigned const * src, unsigned dst_sz, unsigned * dst);
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/**
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\brief Return true if all words of data are zero.
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*/
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bool is_zero(unsigned sz, unsigned const * data);
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/**
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\brief Set all words of data to zero.
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*/
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void reset(unsigned sz, unsigned * data);
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/**
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\brief dst <- src << k
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Store in dst the result of shifting src k bits to the left.
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The result is truncated by dst_sz.
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\pre src_sz != 0
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\pre dst_sz != 0
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*/
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void shl(unsigned src_sz, unsigned const * src, unsigned k, unsigned dst_sz, unsigned * dst);
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/**
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\brief dst <- src >> k
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Store in dst the result of shifting src k bits to the right.
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\pre dst must have size sz.
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\pre src_sz != 0
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\pre dst_sz != 0
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*/
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void shr(unsigned sz, unsigned const * src, unsigned k, unsigned * dst);
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/**
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\brief dst <- src >> k
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Store in dst the result of shifting src k bits to the right.
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Trucate if src_sz > dst_sz.
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Fill range [src_sz, dst_sz) of dst with zeros if dst_sz > src_sz.
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\pre src_sz != 0
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\pre dst_sz != 0
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*/
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void shr(unsigned src_sz, unsigned const * src, unsigned k, unsigned dst_sz, unsigned * dst);
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/**
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\brief Return true if one of the first k bits of src is not zero.
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*/
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bool has_one_at_first_k_bits(unsigned sz, unsigned const * data, unsigned k);
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/**
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\brief data <- data + 1
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Return true if no overflow occurred.
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*/
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bool inc(unsigned sz, unsigned * data);
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/**
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\brief data <- data - 1
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Return true if no underflow occurred.
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*/
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bool dec(unsigned sz, unsigned * data);
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/**
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\brief Return true if data1 < data2.
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Both must have the same size.
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*/
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bool lt(unsigned sz, unsigned * data1, unsigned * data2);
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/**
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\brief Store in c the a+b. This procedure assumes that a,b,c are vectors of size sz.
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Return false if a+b overflows.
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*/
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bool add(unsigned sz, unsigned const * a, unsigned const * b, unsigned * c);
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#endif
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