mirror of
https://bitbucket.org/s_l_teichmann/mtsatellite
synced 2024-09-06 04:40:18 +02:00
317 lines
6.1 KiB
Go
317 lines
6.1 KiB
Go
// Copyright 2014 by Sascha L. Teichmann
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// Use of this source code is governed by the MIT license
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// that can be found in the LICENSE file.
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package common
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import (
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"encoding/binary"
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"fmt"
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"strconv"
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)
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const (
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numBitsPerComponent = 12
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modulo = 1 << numBitsPerComponent
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maxPositive = modulo / 2
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minValue = -1 << (numBitsPerComponent - 1)
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maxValue = 1<<(numBitsPerComponent-1) - 1
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)
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type (
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Coord struct {
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X, Y, Z int16
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}
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Cuboid struct {
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P1, P2 Coord
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}
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KeyTransformer func(int64) int64
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KeyEncoder func(int64) ([]byte, error)
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KeyDecoder func([]byte) (int64, error)
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KeyTranscoder func([]byte) ([]byte, error)
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KeySplitter func(int64) Coord
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KeyJoiner func(Coord) int64
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)
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func (cub Cuboid) Contains(c Coord) bool {
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return c.X >= cub.P1.X && c.X <= cub.P2.X &&
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c.Y >= cub.P1.Y && c.Y <= cub.P2.Y &&
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c.Z >= cub.P1.Z && c.Z <= cub.P2.Z
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}
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func (c Coord) String() string {
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return fmt.Sprintf("(%d, %d, %d)", c.X, c.Y, c.Z)
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}
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func minComponent(a, b int16) int16 {
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if a < b {
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return a
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}
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return b
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}
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func maxComponent(a, b int16) int16 {
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if a > b {
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return a
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}
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return b
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}
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func clipComponent(x int16) int16 {
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if x < minValue {
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return minValue
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}
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if x > maxValue {
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return maxValue
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}
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return x
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}
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func ClipCoord(c Coord) Coord {
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return Coord{
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X: clipComponent(c.X),
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Y: clipComponent(c.Y),
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Z: clipComponent(c.Z)}
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}
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func MinCoord(a, b Coord) Coord {
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return Coord{
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X: minComponent(a.X, b.X),
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Y: minComponent(a.Y, b.Y),
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Z: minComponent(a.Z, b.Z)}
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}
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func MaxCoord(a, b Coord) Coord {
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return Coord{
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X: maxComponent(a.X, b.X),
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Y: maxComponent(a.Y, b.Y),
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Z: maxComponent(a.Z, b.Z)}
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}
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// Constructs a database key out of byte slice.
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func DecodeStringFromBytes(key []byte) (pos int64, err error) {
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return strconv.ParseInt(string(key), 10, 64)
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}
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func StringToBytes(key int64) []byte {
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return []byte(strconv.FormatInt(key, 10))
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}
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// Encode a block pos to byte slice.
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func EncodeStringToBytes(key int64) ([]byte, error) {
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return StringToBytes(key), nil
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}
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func ToBigEndian(key int64) []byte {
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enc := make([]byte, 8)
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binary.BigEndian.PutUint64(enc, uint64(key))
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return enc
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}
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func EncodeToBigEndian(key int64) ([]byte, error) {
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return ToBigEndian(key), nil
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}
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func FromBigEndian(key []byte) int64 {
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return int64(binary.BigEndian.Uint64(key))
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}
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func DecodeFromBigEndian(key []byte) (int64, error) {
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return FromBigEndian(key), nil
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}
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func CoordToInterleaved(c Coord) (result int64) {
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const end = 1 << (numBitsPerComponent + 1)
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x := c.X - minValue
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y := c.Y - minValue
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z := c.Z - minValue
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setmask := int64(1)
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for mask := int16(1); mask != end; mask <<= 1 {
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if x&mask != 0 {
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result |= setmask
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}
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setmask <<= 1
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if y&mask != 0 {
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result |= setmask
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}
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setmask <<= 1
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if z&mask != 0 {
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result |= setmask
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}
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setmask <<= 1
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}
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return
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}
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func invert16(x int16) int16 {
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return -x - 1
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}
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func InterleavedToCoord(pos int64) Coord {
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const end = 1 << (numBitsPerComponent + 1)
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var x, y, z int16
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for mask := int16(1); mask != end; mask <<= 1 {
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if pos&1 == 1 {
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x |= mask
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}
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pos >>= 1
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if pos&1 == 1 {
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y |= mask
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}
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pos >>= 1
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if pos&1 == 1 {
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z |= mask
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}
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pos >>= 1
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}
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return Coord{X: x + minValue, Y: y + minValue, Z: z + minValue}
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}
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func CoordToPlain(c Coord) int64 {
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return int64(c.Z)<<(2*numBitsPerComponent) +
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int64(c.Y)<<numBitsPerComponent +
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int64(c.X)
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}
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func unsignedToSigned(i int16) int16 {
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if i < maxPositive {
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return i
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}
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return i - maxPositive*2
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}
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// To match C++ code.
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func pythonModulo(i int16) int16 {
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const mask = modulo - 1
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if i >= 0 {
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return i & mask
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}
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return modulo - -i&mask
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}
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func PlainToCoord(i int64) (c Coord) {
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c.X = unsignedToSigned(pythonModulo(int16(i)))
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i = (i - int64(c.X)) >> numBitsPerComponent
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c.Y = unsignedToSigned(pythonModulo(int16(i)))
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i = (i - int64(c.Y)) >> numBitsPerComponent
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c.Z = unsignedToSigned(pythonModulo(int16(i)))
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return
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}
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func TransformPlainToInterleaved(pos int64) int64 {
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return CoordToInterleaved(PlainToCoord(pos))
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}
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func TransformInterleavedToPlain(pos int64) int64 {
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return CoordToPlain(InterleavedToCoord(pos))
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}
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func DecodeStringFromBytesToInterleaved(key []byte) (v int64, err error) {
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if v, err = DecodeStringFromBytes(key); err != nil {
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return
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}
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v = TransformPlainToInterleaved(v)
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return
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}
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func EncodeStringToBytesFromInterleaved(key int64) ([]byte, error) {
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return EncodeStringToBytes(TransformInterleavedToPlain(key))
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}
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func IdentityTranscoder(key []byte) ([]byte, error) {
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return key, nil
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}
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func TranscodePlainToInterleaved(key []byte) ([]byte, error) {
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if pos, err := DecodeStringFromBytesToInterleaved(key); err != nil {
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return nil, err
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} else {
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return EncodeToBigEndian(pos)
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}
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}
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func TranscodeInterleavedToPlain(key []byte) ([]byte, error) {
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if pos, err := DecodeFromBigEndian(key); err != nil {
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return nil, err
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} else {
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return EncodeStringToBytes(TransformInterleavedToPlain(pos))
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}
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}
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// For correctness checks only.
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func NaiveBigMin(minz, maxz, zcode int64) int64 {
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var (
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c1 = InterleavedToCoord(minz)
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c2 = InterleavedToCoord(maxz)
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cand = maxz
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c Coord
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)
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for c.X = c1.X; c.X <= c2.X; c.X++ {
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for c.Y = c1.Y; c.Y <= c2.Y; c.Y++ {
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for c.Z = c1.Z; c.Z <= c2.Z; c.Z++ {
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if z := CoordToInterleaved(c); z > zcode && z < cand {
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cand = z
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}
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}
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}
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}
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return cand
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}
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const (
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msb = uint8(3*numBitsPerComponent - 1)
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mask = int64(0x924924924)
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full = int64(0xfffffffff)
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)
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func setbits(p uint8, v int64) int64 {
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m := (mask >> (msb - p)) & (^(full << p) & full)
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return (v | m) & ^(1 << p) & full
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}
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func unsetbits(p uint8, v int64) int64 {
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m := ^(mask >> (msb - p)) & full
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return (v & m) | (int64(1) << p)
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}
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func BigMin(minz, maxz, zcode int64) int64 {
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const (
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_001_ = 1
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_010_ = 2
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_011_ = 2 | 1
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_100_ = 4
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_101_ = 4 | 1
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)
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bigmin := maxz
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pos := msb
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for m := int64(1) << msb; m != 0; m >>= 1 {
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var v uint8
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if zcode&m == m {
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v = _100_
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}
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if minz&m == m {
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v |= _010_
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}
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if maxz&m == m {
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v |= _001_
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}
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switch v {
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case _001_:
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bigmin = unsetbits(pos, minz)
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maxz = setbits(pos, maxz)
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case _011_:
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return minz
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case _100_:
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return bigmin
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case _101_:
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minz = unsetbits(pos, minz)
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}
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pos--
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}
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return bigmin
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}
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