Source file src/pkg/cmd/compile/internal/gc/bitset.go

     1	// Copyright 2017 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	package gc
     6	
     7	type bitset8 uint8
     8	
     9	func (f *bitset8) set(mask uint8, b bool) {
    10		if b {
    11			*(*uint8)(f) |= mask
    12		} else {
    13			*(*uint8)(f) &^= mask
    14		}
    15	}
    16	
    17	type bitset16 uint16
    18	
    19	func (f *bitset16) set(mask uint16, b bool) {
    20		if b {
    21			*(*uint16)(f) |= mask
    22		} else {
    23			*(*uint16)(f) &^= mask
    24		}
    25	}
    26	
    27	type bitset32 uint32
    28	
    29	func (f *bitset32) set(mask uint32, b bool) {
    30		if b {
    31			*(*uint32)(f) |= mask
    32		} else {
    33			*(*uint32)(f) &^= mask
    34		}
    35	}
    36	
    37	func (f bitset32) get2(shift uint8) uint8 {
    38		return uint8(f>>shift) & 3
    39	}
    40	
    41	// set2 sets two bits in f using the bottom two bits of b.
    42	func (f *bitset32) set2(shift uint8, b uint8) {
    43		// Clear old bits.
    44		*(*uint32)(f) &^= 3 << shift
    45		// Set new bits.
    46		*(*uint32)(f) |= uint32(b&3) << shift
    47	}
    48	
    49	func (f bitset32) get3(shift uint8) uint8 {
    50		return uint8(f>>shift) & 7
    51	}
    52	
    53	// set3 sets three bits in f using the bottom three bits of b.
    54	func (f *bitset32) set3(shift uint8, b uint8) {
    55		// Clear old bits.
    56		*(*uint32)(f) &^= 7 << shift
    57		// Set new bits.
    58		*(*uint32)(f) |= uint32(b&7) << shift
    59	}
    60	

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