Documentation
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Index ¶
- Variables
- func BitIsNotSet(buf []byte, i int) bool
- func BitIsSet(buf []byte, i int) bool
- func BytesForBits(bits int64) int64
- func CeilByte(size int) int
- func CeilByte64(size int64) int64
- func ClearBit(buf []byte, i int)
- func CopyBitmap(src []byte, srcOffset, length int, dst []byte, dstOffset int)
- func CountSetBits(buf []byte, offset, n int) int
- func IsMultipleOf64(v int64) bool
- func IsMultipleOf8(v int64) bool
- func NextPowerOf2(x int) int
- func SetBit(buf []byte, i int)
- func SetBitTo(buf []byte, i int, val bool)
- func SetBitsTo(bits []byte, startOffset, length int64, areSet bool)
- type BitmapReader
- type BitmapWordReader
- type BitmapWordWriter
- type BitmapWriter
Constants ¶
This section is empty.
Variables ¶
var ( BitMask = [8]byte{1, 2, 4, 8, 16, 32, 64, 128} FlippedBitMask = [8]byte{254, 253, 251, 247, 239, 223, 191, 127} )
var ( // PrecedingBitmask is a convenience set of values as bitmasks for checking // prefix bits of a byte PrecedingBitmask = [8]byte{0, 1, 3, 7, 15, 31, 63, 127} // TrailingBitmask is the bitwise complement version of kPrecedingBitmask TrailingBitmask = [8]byte{255, 254, 252, 248, 240, 224, 192, 128} )
Functions ¶
func BitIsNotSet ¶
BitIsNotSet returns true if the bit at index i in buf is not set (0).
func BytesForBits ¶
func CeilByte64 ¶
CeilByte64 rounds size to the next multiple of 8.
func CopyBitmap ¶
CopyBitmap copies the bitmap indicated by src, starting at bit offset srcOffset, and copying length bits into dst, starting at bit offset dstOffset.
func CountSetBits ¶
CountSetBits counts the number of 1's in buf up to n bits.
func IsMultipleOf64 ¶
IsMultipleOf64 returns whether v is a multiple of 64
func IsMultipleOf8 ¶
IsMultipleOf8 returns whether v is a multiple of 8.
Types ¶
type BitmapReader ¶
type BitmapReader struct {
// contains filtered or unexported fields
}
BitmapReader is a simple bitmap reader for a byte slice.
func NewBitmapReader ¶
func NewBitmapReader(bitmap []byte, offset, length int) *BitmapReader
NewBitmapReader creates and returns a new bitmap reader for the given bitmap
func (*BitmapReader) Len ¶
func (b *BitmapReader) Len() int
Len returns the total number of bits in the bitmap
func (*BitmapReader) Next ¶
func (b *BitmapReader) Next()
Next advances the reader to the next bit in the bitmap.
func (*BitmapReader) NotSet ¶
func (b *BitmapReader) NotSet() bool
NotSet returns true if the current bit is not set
func (*BitmapReader) Pos ¶
func (b *BitmapReader) Pos() int
Pos returns the current bit position in the bitmap that the reader is looking at
func (*BitmapReader) Set ¶
func (b *BitmapReader) Set() bool
Set returns true if the current bit is set
type BitmapWordReader ¶
type BitmapWordReader struct {
// contains filtered or unexported fields
}
BitmapWordReader is a reader for bitmaps that reads a word at a time (a word being an 8 byte uint64) and then provides functions to grab the individual trailing bytes after the last word
func NewBitmapWordReader ¶
func NewBitmapWordReader(bitmap []byte, offset, length int) *BitmapWordReader
NewBitmapWordReader sets up a word reader, calculates the number of trailing bits and number of trailing bytes, along with the number of words.
func (*BitmapWordReader) NextTrailingByte ¶
func (bm *BitmapWordReader) NextTrailingByte() (val byte, validBits int)
NextTrailingByte returns the next trailing byte of the bitmap after the last word along with the number of valid bits in that byte. When validBits < 8, that is the last byte.
If the bitmap ends on a byte alignment, then the last byte can also return 8 valid bits. Thus the TrailingBytes function should be used to know how many trailing bytes to read.
func (*BitmapWordReader) NextWord ¶
func (bm *BitmapWordReader) NextWord() uint64
NextWord returns the next full word read from the bitmap, should not be called if Words() is 0 as it will step outside of the bounds of the bitmap slice and panic.
We don't perform the bounds checking in order to improve performance.
func (*BitmapWordReader) TrailingBytes ¶
func (bm *BitmapWordReader) TrailingBytes() int
func (*BitmapWordReader) Words ¶
func (bm *BitmapWordReader) Words() int
type BitmapWordWriter ¶
type BitmapWordWriter struct {
// contains filtered or unexported fields
}
BitmapWordWriter is a bitmap writer for writing a full word at a time (a word being a uint64). After the last full word is written, PutNextTrailingByte can be used to write the remaining trailing bytes.
func NewBitmapWordWriter ¶
func NewBitmapWordWriter(bitmap []byte, start, len int) *BitmapWordWriter
NewBitmapWordWriter initializes a new bitmap word writer which will start writing into the byte slice at bit offset start, expecting to write len bits.
func (*BitmapWordWriter) PutNextTrailingByte ¶
func (bm *BitmapWordWriter) PutNextTrailingByte(b byte, validBits int)
PutNextTrailingByte writes the number of bits indicated by validBits from b to the bitmap.
func (*BitmapWordWriter) PutNextWord ¶
func (bm *BitmapWordWriter) PutNextWord(word uint64)
PutNextWord writes the given word to the bitmap, potentially splitting across two adjacent words.
type BitmapWriter ¶
type BitmapWriter struct {
// contains filtered or unexported fields
}
BitmapWriter is a simple writer for writing bitmaps to byte slices
func NewBitmapWriter ¶
func NewBitmapWriter(bitmap []byte, start, length int) *BitmapWriter
NewBitmapWriter returns a sequential bitwise writer that preserves surrounding bit values as it writes.
func (*BitmapWriter) AppendBools ¶
func (b *BitmapWriter) AppendBools(in []bool) int
AppendBools writes a series of booleans to the bitmapwriter and returns the number of remaining bytes left in the buffer for writing.
func (*BitmapWriter) Clear ¶
func (b *BitmapWriter) Clear()
func (*BitmapWriter) Finish ¶
func (b *BitmapWriter) Finish()
Finish flushes the final byte out to the byteslice in case it was not already on a byte aligned boundary.
func (*BitmapWriter) Next ¶
func (b *BitmapWriter) Next()
Next increments the writer to the next bit for writing.
func (*BitmapWriter) Pos ¶
func (b *BitmapWriter) Pos() int
func (*BitmapWriter) Reset ¶
func (b *BitmapWriter) Reset(start, length int)
Reset resets the position and view of the slice to restart writing a bitmap to the same byte slice.
func (*BitmapWriter) Set ¶
func (b *BitmapWriter) Set()
Source Files