133 lines
1.7 KiB
C++
133 lines
1.7 KiB
C++
// Copyright (c) 1997-1999 Microsoft Corporation
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//
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// bit twiddling stuff
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//
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// 8-5-98 sburns
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// One would think that after n decades of C, these would be builtin
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// keywords...
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// Returns state of bit n: true if it is set, false if not
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//
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// bits - set of bits
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//
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// n - bit to test
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inline
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bool
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getbit(ULONG bits, unsigned int n)
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{
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if (bits & (1 << n))
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{
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return true;
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}
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return false;
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}
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// flips bit n (sets it to the opposite state), returns new state of bit n
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//
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// bits - set of bits.
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//
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// n - bit to flip
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inline
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bool
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flipbit(ULONG& bits, unsigned int n)
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{
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return getbit((bits ^= (1 << n)), n);
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}
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// sets bit n to 1
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//
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// bits - set of bits
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//
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// n - bit to set
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inline
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void
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setbit(ULONG& bits, unsigned int n)
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{
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bits |= (1 << n);
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}
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// sets bit n to 0
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//
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// bits - set of bits
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//
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// n - bit to clear
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inline
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void
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clearbit(ULONG& bits, unsigned int n)
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{
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ULONG mask = (1 << n);
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bits &= ~mask;
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}
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// Sets all bits in mask. Returns result
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//
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// bits - holds bits to be set
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//
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// mask - mask of bits to set
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inline
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DWORD
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setbits(ULONG& bits, ULONG mask)
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{
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ASSERT(mask);
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bits |= mask;
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return bits;
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}
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// Clears all bits in mask. Returns result.
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//
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// bits - holds bits to be cleared
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//
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// mask - mask of bits to clear
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inline
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DWORD
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clearbits(ULONG& bits, ULONG mask)
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{
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ASSERT(mask);
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bits &= ~mask;
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return bits;
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}
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// Toggles all bits in mask. bits that were set are cleared, and vice-
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// versa. Returns result.
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//
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// bits - holds bits to be toggled
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//
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// mask - mask of bits to toggled
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inline
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DWORD
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flipbits(ULONG& bits, ULONG mask)
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{
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bits ^= mask;
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return bits;
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}
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