119 lines
2.2 KiB
Go
119 lines
2.2 KiB
Go
package bitmask
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import (
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"bytes"
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"errors"
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"encoding/binary"
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"math/bits"
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)
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// MaskBit is a flag container.
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type MaskBit uint
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/*
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NewMaskBit is a convenience function.
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It will return a MaskBit with a (referenced) value of 0, so set your consts up accordingly.
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It is highly recommended to set this default as a "None" flag (separate from your iotas!)
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as shown in the example.
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*/
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func NewMaskBit() (m *MaskBit) {
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m = new(MaskBit)
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return
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}
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// NewMaskBitExplicit is like NewMaskBit, but allows you to specify a non-zero (0x0) value.
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func NewMaskBitExplicit(value uint) (m *MaskBit) {
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var v MaskBit = MaskBit(value)
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m = &v
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return
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}
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// HasFlag is true if m has MaskBit flag set/enabled.
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func (m *MaskBit) HasFlag(flag MaskBit) (r bool) {
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var b MaskBit = *m
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if b&flag != 0 {
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r = true
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}
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return
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}
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// AddFlag adds MaskBit flag to m.
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func (m *MaskBit) AddFlag(flag MaskBit) {
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*m |= flag
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return
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}
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// ClearFlag removes MaskBit flag from m.
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func (m *MaskBit) ClearFlag(flag MaskBit) {
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*m &= flag
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return
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}
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// ToggleFlag switches MaskBit flag in m to its inverse; if true, it is now false and vice versa.
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func (m *MaskBit) ToggleFlag(flag MaskBit) {
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*m ^= flag
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return
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}
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/*
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Bytes returns the current value of a MasBit as a byte slice (big-endian).
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If trim is false, b will (probably) be 4 bytes long if you're on a 32-bit size system,
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and b will (probably) be 8 bytes long if you're on a 64-bit size system. You can determine
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the size of the resulting slice via (math/)bits.UintSize / 8.
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If trim is true, it will trim leading null bytes (if any). This will lead to an unpredictable
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byte slice length in b, but is most likely preferred for byte operations.
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*/
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func (m *MaskBit) Bytes(trim bool) (b []byte) {
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var b2 []byte
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var size int = bits.UintSize / 8
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var err error
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b2 = make([]byte, size)
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switch s := bits.UintSize; s {
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case 32:
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binary.BigEndian.PutUint32(b2[:], uint32(*m))
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case 64:
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binary.BigEndian.PutUint64(b2[:], uint64(*m))
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default:
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err = errors.New("unsupported Uint/system bit size")
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panic(err)
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}
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if trim {
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b = bytes.TrimLeft(b2, "\x00")
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return
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} else {
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b = b2
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return
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}
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return
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}
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// Value returns the current raw uint value of a MaskBit.
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func (m *MaskBit) Value() (v uint) {
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v = uint(*m)
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return
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}
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