78 lines
1.7 KiB
Go
78 lines
1.7 KiB
Go
package tsm1
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import (
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"encoding/binary"
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"fmt"
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)
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// BooleanArrayEncodeAll encodes src into b, returning b and any error encountered.
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// The returned slice may be of a different length and capacity to b.
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func BooleanArrayEncodeAll(src []bool, b []byte) ([]byte, error) {
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sz := 1 + 8 + ((len(src) + 7) / 8) // Header + Num bools + bool data.
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if len(b) < sz && cap(b) > sz {
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b = b[:sz]
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} else if len(b) < sz {
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b = append(b, make([]byte, sz)...)
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}
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// Store the encoding type in the 4 high bits of the first byte
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b[0] = byte(booleanCompressedBitPacked) << 4
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n := uint64(8) // Current bit in current byte.
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// Encode the number of booleans written.
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i := binary.PutUvarint(b[n>>3:], uint64(len(src)))
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n += uint64(i * 8)
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for _, v := range src {
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if v {
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b[n>>3] |= 128 >> (n & 7) // Set current bit on current byte.
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} else {
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b[n>>3] &^= 128 >> (n & 7) // Clear current bit on current byte.
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}
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n++
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}
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length := n >> 3
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if n&7 > 0 {
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length++ // Add an extra byte to capture overflowing bits.
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}
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return b[:length], nil
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}
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func BooleanArrayDecodeAll(b []byte, dst []bool) ([]bool, error) {
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if len(b) == 0 {
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return nil, nil
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}
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// First byte stores the encoding type, only have 1 bit-packet format
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// currently ignore for now.
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b = b[1:]
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val, n := binary.Uvarint(b)
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if n <= 0 {
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return nil, fmt.Errorf("BooleanBatchDecoder: invalid count")
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}
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count := int(val)
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b = b[n:]
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if min := len(b) * 8; min < count {
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// Shouldn't happen - TSM file was truncated/corrupted
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count = min
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}
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if cap(dst) < count {
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dst = make([]bool, count)
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} else {
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dst = dst[:count]
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}
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j := 0
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for _, v := range b {
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for i := byte(128); i > 0 && j < len(dst); i >>= 1 {
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dst[j] = v&i != 0
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j++
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}
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}
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return dst, nil
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}
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