mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
synced 2024-12-22 00:16:23 +01:00
684 lines
17 KiB
Go
684 lines
17 KiB
Go
// Copyright 2018 Klaus Post. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
|
|
|
|
package fse
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
)
|
|
|
|
// Compress the input bytes. Input must be < 2GB.
|
|
// Provide a Scratch buffer to avoid memory allocations.
|
|
// Note that the output is also kept in the scratch buffer.
|
|
// If input is too hard to compress, ErrIncompressible is returned.
|
|
// If input is a single byte value repeated ErrUseRLE is returned.
|
|
func Compress(in []byte, s *Scratch) ([]byte, error) {
|
|
if len(in) <= 1 {
|
|
return nil, ErrIncompressible
|
|
}
|
|
if len(in) > (2<<30)-1 {
|
|
return nil, errors.New("input too big, must be < 2GB")
|
|
}
|
|
s, err := s.prepare(in)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Create histogram, if none was provided.
|
|
maxCount := s.maxCount
|
|
if maxCount == 0 {
|
|
maxCount = s.countSimple(in)
|
|
}
|
|
// Reset for next run.
|
|
s.clearCount = true
|
|
s.maxCount = 0
|
|
if maxCount == len(in) {
|
|
// One symbol, use RLE
|
|
return nil, ErrUseRLE
|
|
}
|
|
if maxCount == 1 || maxCount < (len(in)>>7) {
|
|
// Each symbol present maximum once or too well distributed.
|
|
return nil, ErrIncompressible
|
|
}
|
|
s.optimalTableLog()
|
|
err = s.normalizeCount()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
err = s.writeCount()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
if false {
|
|
err = s.validateNorm()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
|
|
err = s.buildCTable()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
err = s.compress(in)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
s.Out = s.bw.out
|
|
// Check if we compressed.
|
|
if len(s.Out) >= len(in) {
|
|
return nil, ErrIncompressible
|
|
}
|
|
return s.Out, nil
|
|
}
|
|
|
|
// cState contains the compression state of a stream.
|
|
type cState struct {
|
|
bw *bitWriter
|
|
stateTable []uint16
|
|
state uint16
|
|
}
|
|
|
|
// init will initialize the compression state to the first symbol of the stream.
|
|
func (c *cState) init(bw *bitWriter, ct *cTable, tableLog uint8, first symbolTransform) {
|
|
c.bw = bw
|
|
c.stateTable = ct.stateTable
|
|
|
|
nbBitsOut := (first.deltaNbBits + (1 << 15)) >> 16
|
|
im := int32((nbBitsOut << 16) - first.deltaNbBits)
|
|
lu := (im >> nbBitsOut) + first.deltaFindState
|
|
c.state = c.stateTable[lu]
|
|
}
|
|
|
|
// encode the output symbol provided and write it to the bitstream.
|
|
func (c *cState) encode(symbolTT symbolTransform) {
|
|
nbBitsOut := (uint32(c.state) + symbolTT.deltaNbBits) >> 16
|
|
dstState := int32(c.state>>(nbBitsOut&15)) + symbolTT.deltaFindState
|
|
c.bw.addBits16NC(c.state, uint8(nbBitsOut))
|
|
c.state = c.stateTable[dstState]
|
|
}
|
|
|
|
// encode the output symbol provided and write it to the bitstream.
|
|
func (c *cState) encodeZero(symbolTT symbolTransform) {
|
|
nbBitsOut := (uint32(c.state) + symbolTT.deltaNbBits) >> 16
|
|
dstState := int32(c.state>>(nbBitsOut&15)) + symbolTT.deltaFindState
|
|
c.bw.addBits16ZeroNC(c.state, uint8(nbBitsOut))
|
|
c.state = c.stateTable[dstState]
|
|
}
|
|
|
|
// flush will write the tablelog to the output and flush the remaining full bytes.
|
|
func (c *cState) flush(tableLog uint8) {
|
|
c.bw.flush32()
|
|
c.bw.addBits16NC(c.state, tableLog)
|
|
c.bw.flush()
|
|
}
|
|
|
|
// compress is the main compression loop that will encode the input from the last byte to the first.
|
|
func (s *Scratch) compress(src []byte) error {
|
|
if len(src) <= 2 {
|
|
return errors.New("compress: src too small")
|
|
}
|
|
tt := s.ct.symbolTT[:256]
|
|
s.bw.reset(s.Out)
|
|
|
|
// Our two states each encodes every second byte.
|
|
// Last byte encoded (first byte decoded) will always be encoded by c1.
|
|
var c1, c2 cState
|
|
|
|
// Encode so remaining size is divisible by 4.
|
|
ip := len(src)
|
|
if ip&1 == 1 {
|
|
c1.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-1]])
|
|
c2.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-2]])
|
|
c1.encodeZero(tt[src[ip-3]])
|
|
ip -= 3
|
|
} else {
|
|
c2.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-1]])
|
|
c1.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-2]])
|
|
ip -= 2
|
|
}
|
|
if ip&2 != 0 {
|
|
c2.encodeZero(tt[src[ip-1]])
|
|
c1.encodeZero(tt[src[ip-2]])
|
|
ip -= 2
|
|
}
|
|
src = src[:ip]
|
|
|
|
// Main compression loop.
|
|
switch {
|
|
case !s.zeroBits && s.actualTableLog <= 8:
|
|
// We can encode 4 symbols without requiring a flush.
|
|
// We do not need to check if any output is 0 bits.
|
|
for ; len(src) >= 4; src = src[:len(src)-4] {
|
|
s.bw.flush32()
|
|
v3, v2, v1, v0 := src[len(src)-4], src[len(src)-3], src[len(src)-2], src[len(src)-1]
|
|
c2.encode(tt[v0])
|
|
c1.encode(tt[v1])
|
|
c2.encode(tt[v2])
|
|
c1.encode(tt[v3])
|
|
}
|
|
case !s.zeroBits:
|
|
// We do not need to check if any output is 0 bits.
|
|
for ; len(src) >= 4; src = src[:len(src)-4] {
|
|
s.bw.flush32()
|
|
v3, v2, v1, v0 := src[len(src)-4], src[len(src)-3], src[len(src)-2], src[len(src)-1]
|
|
c2.encode(tt[v0])
|
|
c1.encode(tt[v1])
|
|
s.bw.flush32()
|
|
c2.encode(tt[v2])
|
|
c1.encode(tt[v3])
|
|
}
|
|
case s.actualTableLog <= 8:
|
|
// We can encode 4 symbols without requiring a flush
|
|
for ; len(src) >= 4; src = src[:len(src)-4] {
|
|
s.bw.flush32()
|
|
v3, v2, v1, v0 := src[len(src)-4], src[len(src)-3], src[len(src)-2], src[len(src)-1]
|
|
c2.encodeZero(tt[v0])
|
|
c1.encodeZero(tt[v1])
|
|
c2.encodeZero(tt[v2])
|
|
c1.encodeZero(tt[v3])
|
|
}
|
|
default:
|
|
for ; len(src) >= 4; src = src[:len(src)-4] {
|
|
s.bw.flush32()
|
|
v3, v2, v1, v0 := src[len(src)-4], src[len(src)-3], src[len(src)-2], src[len(src)-1]
|
|
c2.encodeZero(tt[v0])
|
|
c1.encodeZero(tt[v1])
|
|
s.bw.flush32()
|
|
c2.encodeZero(tt[v2])
|
|
c1.encodeZero(tt[v3])
|
|
}
|
|
}
|
|
|
|
// Flush final state.
|
|
// Used to initialize state when decoding.
|
|
c2.flush(s.actualTableLog)
|
|
c1.flush(s.actualTableLog)
|
|
|
|
s.bw.close()
|
|
return nil
|
|
}
|
|
|
|
// writeCount will write the normalized histogram count to header.
|
|
// This is read back by readNCount.
|
|
func (s *Scratch) writeCount() error {
|
|
var (
|
|
tableLog = s.actualTableLog
|
|
tableSize = 1 << tableLog
|
|
previous0 bool
|
|
charnum uint16
|
|
|
|
maxHeaderSize = ((int(s.symbolLen) * int(tableLog)) >> 3) + 3
|
|
|
|
// Write Table Size
|
|
bitStream = uint32(tableLog - minTablelog)
|
|
bitCount = uint(4)
|
|
remaining = int16(tableSize + 1) /* +1 for extra accuracy */
|
|
threshold = int16(tableSize)
|
|
nbBits = uint(tableLog + 1)
|
|
)
|
|
if cap(s.Out) < maxHeaderSize {
|
|
s.Out = make([]byte, 0, s.br.remain()+maxHeaderSize)
|
|
}
|
|
outP := uint(0)
|
|
out := s.Out[:maxHeaderSize]
|
|
|
|
// stops at 1
|
|
for remaining > 1 {
|
|
if previous0 {
|
|
start := charnum
|
|
for s.norm[charnum] == 0 {
|
|
charnum++
|
|
}
|
|
for charnum >= start+24 {
|
|
start += 24
|
|
bitStream += uint32(0xFFFF) << bitCount
|
|
out[outP] = byte(bitStream)
|
|
out[outP+1] = byte(bitStream >> 8)
|
|
outP += 2
|
|
bitStream >>= 16
|
|
}
|
|
for charnum >= start+3 {
|
|
start += 3
|
|
bitStream += 3 << bitCount
|
|
bitCount += 2
|
|
}
|
|
bitStream += uint32(charnum-start) << bitCount
|
|
bitCount += 2
|
|
if bitCount > 16 {
|
|
out[outP] = byte(bitStream)
|
|
out[outP+1] = byte(bitStream >> 8)
|
|
outP += 2
|
|
bitStream >>= 16
|
|
bitCount -= 16
|
|
}
|
|
}
|
|
|
|
count := s.norm[charnum]
|
|
charnum++
|
|
max := (2*threshold - 1) - remaining
|
|
if count < 0 {
|
|
remaining += count
|
|
} else {
|
|
remaining -= count
|
|
}
|
|
count++ // +1 for extra accuracy
|
|
if count >= threshold {
|
|
count += max // [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[
|
|
}
|
|
bitStream += uint32(count) << bitCount
|
|
bitCount += nbBits
|
|
if count < max {
|
|
bitCount--
|
|
}
|
|
|
|
previous0 = count == 1
|
|
if remaining < 1 {
|
|
return errors.New("internal error: remaining<1")
|
|
}
|
|
for remaining < threshold {
|
|
nbBits--
|
|
threshold >>= 1
|
|
}
|
|
|
|
if bitCount > 16 {
|
|
out[outP] = byte(bitStream)
|
|
out[outP+1] = byte(bitStream >> 8)
|
|
outP += 2
|
|
bitStream >>= 16
|
|
bitCount -= 16
|
|
}
|
|
}
|
|
|
|
out[outP] = byte(bitStream)
|
|
out[outP+1] = byte(bitStream >> 8)
|
|
outP += (bitCount + 7) / 8
|
|
|
|
if charnum > s.symbolLen {
|
|
return errors.New("internal error: charnum > s.symbolLen")
|
|
}
|
|
s.Out = out[:outP]
|
|
return nil
|
|
}
|
|
|
|
// symbolTransform contains the state transform for a symbol.
|
|
type symbolTransform struct {
|
|
deltaFindState int32
|
|
deltaNbBits uint32
|
|
}
|
|
|
|
// String prints values as a human readable string.
|
|
func (s symbolTransform) String() string {
|
|
return fmt.Sprintf("dnbits: %08x, fs:%d", s.deltaNbBits, s.deltaFindState)
|
|
}
|
|
|
|
// cTable contains tables used for compression.
|
|
type cTable struct {
|
|
tableSymbol []byte
|
|
stateTable []uint16
|
|
symbolTT []symbolTransform
|
|
}
|
|
|
|
// allocCtable will allocate tables needed for compression.
|
|
// If existing tables a re big enough, they are simply re-used.
|
|
func (s *Scratch) allocCtable() {
|
|
tableSize := 1 << s.actualTableLog
|
|
// get tableSymbol that is big enough.
|
|
if cap(s.ct.tableSymbol) < tableSize {
|
|
s.ct.tableSymbol = make([]byte, tableSize)
|
|
}
|
|
s.ct.tableSymbol = s.ct.tableSymbol[:tableSize]
|
|
|
|
ctSize := tableSize
|
|
if cap(s.ct.stateTable) < ctSize {
|
|
s.ct.stateTable = make([]uint16, ctSize)
|
|
}
|
|
s.ct.stateTable = s.ct.stateTable[:ctSize]
|
|
|
|
if cap(s.ct.symbolTT) < 256 {
|
|
s.ct.symbolTT = make([]symbolTransform, 256)
|
|
}
|
|
s.ct.symbolTT = s.ct.symbolTT[:256]
|
|
}
|
|
|
|
// buildCTable will populate the compression table so it is ready to be used.
|
|
func (s *Scratch) buildCTable() error {
|
|
tableSize := uint32(1 << s.actualTableLog)
|
|
highThreshold := tableSize - 1
|
|
var cumul [maxSymbolValue + 2]int16
|
|
|
|
s.allocCtable()
|
|
tableSymbol := s.ct.tableSymbol[:tableSize]
|
|
// symbol start positions
|
|
{
|
|
cumul[0] = 0
|
|
for ui, v := range s.norm[:s.symbolLen-1] {
|
|
u := byte(ui) // one less than reference
|
|
if v == -1 {
|
|
// Low proba symbol
|
|
cumul[u+1] = cumul[u] + 1
|
|
tableSymbol[highThreshold] = u
|
|
highThreshold--
|
|
} else {
|
|
cumul[u+1] = cumul[u] + v
|
|
}
|
|
}
|
|
// Encode last symbol separately to avoid overflowing u
|
|
u := int(s.symbolLen - 1)
|
|
v := s.norm[s.symbolLen-1]
|
|
if v == -1 {
|
|
// Low proba symbol
|
|
cumul[u+1] = cumul[u] + 1
|
|
tableSymbol[highThreshold] = byte(u)
|
|
highThreshold--
|
|
} else {
|
|
cumul[u+1] = cumul[u] + v
|
|
}
|
|
if uint32(cumul[s.symbolLen]) != tableSize {
|
|
return fmt.Errorf("internal error: expected cumul[s.symbolLen] (%d) == tableSize (%d)", cumul[s.symbolLen], tableSize)
|
|
}
|
|
cumul[s.symbolLen] = int16(tableSize) + 1
|
|
}
|
|
// Spread symbols
|
|
s.zeroBits = false
|
|
{
|
|
step := tableStep(tableSize)
|
|
tableMask := tableSize - 1
|
|
var position uint32
|
|
// if any symbol > largeLimit, we may have 0 bits output.
|
|
largeLimit := int16(1 << (s.actualTableLog - 1))
|
|
for ui, v := range s.norm[:s.symbolLen] {
|
|
symbol := byte(ui)
|
|
if v > largeLimit {
|
|
s.zeroBits = true
|
|
}
|
|
for nbOccurrences := int16(0); nbOccurrences < v; nbOccurrences++ {
|
|
tableSymbol[position] = symbol
|
|
position = (position + step) & tableMask
|
|
for position > highThreshold {
|
|
position = (position + step) & tableMask
|
|
} /* Low proba area */
|
|
}
|
|
}
|
|
|
|
// Check if we have gone through all positions
|
|
if position != 0 {
|
|
return errors.New("position!=0")
|
|
}
|
|
}
|
|
|
|
// Build table
|
|
table := s.ct.stateTable
|
|
{
|
|
tsi := int(tableSize)
|
|
for u, v := range tableSymbol {
|
|
// TableU16 : sorted by symbol order; gives next state value
|
|
table[cumul[v]] = uint16(tsi + u)
|
|
cumul[v]++
|
|
}
|
|
}
|
|
|
|
// Build Symbol Transformation Table
|
|
{
|
|
total := int16(0)
|
|
symbolTT := s.ct.symbolTT[:s.symbolLen]
|
|
tableLog := s.actualTableLog
|
|
tl := (uint32(tableLog) << 16) - (1 << tableLog)
|
|
for i, v := range s.norm[:s.symbolLen] {
|
|
switch v {
|
|
case 0:
|
|
case -1, 1:
|
|
symbolTT[i].deltaNbBits = tl
|
|
symbolTT[i].deltaFindState = int32(total - 1)
|
|
total++
|
|
default:
|
|
maxBitsOut := uint32(tableLog) - highBits(uint32(v-1))
|
|
minStatePlus := uint32(v) << maxBitsOut
|
|
symbolTT[i].deltaNbBits = (maxBitsOut << 16) - minStatePlus
|
|
symbolTT[i].deltaFindState = int32(total - v)
|
|
total += v
|
|
}
|
|
}
|
|
if total != int16(tableSize) {
|
|
return fmt.Errorf("total mismatch %d (got) != %d (want)", total, tableSize)
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// countSimple will create a simple histogram in s.count.
|
|
// Returns the biggest count.
|
|
// Does not update s.clearCount.
|
|
func (s *Scratch) countSimple(in []byte) (max int) {
|
|
for _, v := range in {
|
|
s.count[v]++
|
|
}
|
|
m, symlen := uint32(0), s.symbolLen
|
|
for i, v := range s.count[:] {
|
|
if v == 0 {
|
|
continue
|
|
}
|
|
if v > m {
|
|
m = v
|
|
}
|
|
symlen = uint16(i) + 1
|
|
}
|
|
s.symbolLen = symlen
|
|
return int(m)
|
|
}
|
|
|
|
// minTableLog provides the minimum logSize to safely represent a distribution.
|
|
func (s *Scratch) minTableLog() uint8 {
|
|
minBitsSrc := highBits(uint32(s.br.remain()-1)) + 1
|
|
minBitsSymbols := highBits(uint32(s.symbolLen-1)) + 2
|
|
if minBitsSrc < minBitsSymbols {
|
|
return uint8(minBitsSrc)
|
|
}
|
|
return uint8(minBitsSymbols)
|
|
}
|
|
|
|
// optimalTableLog calculates and sets the optimal tableLog in s.actualTableLog
|
|
func (s *Scratch) optimalTableLog() {
|
|
tableLog := s.TableLog
|
|
minBits := s.minTableLog()
|
|
maxBitsSrc := uint8(highBits(uint32(s.br.remain()-1))) - 2
|
|
if maxBitsSrc < tableLog {
|
|
// Accuracy can be reduced
|
|
tableLog = maxBitsSrc
|
|
}
|
|
if minBits > tableLog {
|
|
tableLog = minBits
|
|
}
|
|
// Need a minimum to safely represent all symbol values
|
|
if tableLog < minTablelog {
|
|
tableLog = minTablelog
|
|
}
|
|
if tableLog > maxTableLog {
|
|
tableLog = maxTableLog
|
|
}
|
|
s.actualTableLog = tableLog
|
|
}
|
|
|
|
var rtbTable = [...]uint32{0, 473195, 504333, 520860, 550000, 700000, 750000, 830000}
|
|
|
|
// normalizeCount will normalize the count of the symbols so
|
|
// the total is equal to the table size.
|
|
func (s *Scratch) normalizeCount() error {
|
|
var (
|
|
tableLog = s.actualTableLog
|
|
scale = 62 - uint64(tableLog)
|
|
step = (1 << 62) / uint64(s.br.remain())
|
|
vStep = uint64(1) << (scale - 20)
|
|
stillToDistribute = int16(1 << tableLog)
|
|
largest int
|
|
largestP int16
|
|
lowThreshold = (uint32)(s.br.remain() >> tableLog)
|
|
)
|
|
|
|
for i, cnt := range s.count[:s.symbolLen] {
|
|
// already handled
|
|
// if (count[s] == s.length) return 0; /* rle special case */
|
|
|
|
if cnt == 0 {
|
|
s.norm[i] = 0
|
|
continue
|
|
}
|
|
if cnt <= lowThreshold {
|
|
s.norm[i] = -1
|
|
stillToDistribute--
|
|
} else {
|
|
proba := (int16)((uint64(cnt) * step) >> scale)
|
|
if proba < 8 {
|
|
restToBeat := vStep * uint64(rtbTable[proba])
|
|
v := uint64(cnt)*step - (uint64(proba) << scale)
|
|
if v > restToBeat {
|
|
proba++
|
|
}
|
|
}
|
|
if proba > largestP {
|
|
largestP = proba
|
|
largest = i
|
|
}
|
|
s.norm[i] = proba
|
|
stillToDistribute -= proba
|
|
}
|
|
}
|
|
|
|
if -stillToDistribute >= (s.norm[largest] >> 1) {
|
|
// corner case, need another normalization method
|
|
return s.normalizeCount2()
|
|
}
|
|
s.norm[largest] += stillToDistribute
|
|
return nil
|
|
}
|
|
|
|
// Secondary normalization method.
|
|
// To be used when primary method fails.
|
|
func (s *Scratch) normalizeCount2() error {
|
|
const notYetAssigned = -2
|
|
var (
|
|
distributed uint32
|
|
total = uint32(s.br.remain())
|
|
tableLog = s.actualTableLog
|
|
lowThreshold = total >> tableLog
|
|
lowOne = (total * 3) >> (tableLog + 1)
|
|
)
|
|
for i, cnt := range s.count[:s.symbolLen] {
|
|
if cnt == 0 {
|
|
s.norm[i] = 0
|
|
continue
|
|
}
|
|
if cnt <= lowThreshold {
|
|
s.norm[i] = -1
|
|
distributed++
|
|
total -= cnt
|
|
continue
|
|
}
|
|
if cnt <= lowOne {
|
|
s.norm[i] = 1
|
|
distributed++
|
|
total -= cnt
|
|
continue
|
|
}
|
|
s.norm[i] = notYetAssigned
|
|
}
|
|
toDistribute := (1 << tableLog) - distributed
|
|
|
|
if (total / toDistribute) > lowOne {
|
|
// risk of rounding to zero
|
|
lowOne = (total * 3) / (toDistribute * 2)
|
|
for i, cnt := range s.count[:s.symbolLen] {
|
|
if (s.norm[i] == notYetAssigned) && (cnt <= lowOne) {
|
|
s.norm[i] = 1
|
|
distributed++
|
|
total -= cnt
|
|
continue
|
|
}
|
|
}
|
|
toDistribute = (1 << tableLog) - distributed
|
|
}
|
|
if distributed == uint32(s.symbolLen)+1 {
|
|
// all values are pretty poor;
|
|
// probably incompressible data (should have already been detected);
|
|
// find max, then give all remaining points to max
|
|
var maxV int
|
|
var maxC uint32
|
|
for i, cnt := range s.count[:s.symbolLen] {
|
|
if cnt > maxC {
|
|
maxV = i
|
|
maxC = cnt
|
|
}
|
|
}
|
|
s.norm[maxV] += int16(toDistribute)
|
|
return nil
|
|
}
|
|
|
|
if total == 0 {
|
|
// all of the symbols were low enough for the lowOne or lowThreshold
|
|
for i := uint32(0); toDistribute > 0; i = (i + 1) % (uint32(s.symbolLen)) {
|
|
if s.norm[i] > 0 {
|
|
toDistribute--
|
|
s.norm[i]++
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
var (
|
|
vStepLog = 62 - uint64(tableLog)
|
|
mid = uint64((1 << (vStepLog - 1)) - 1)
|
|
rStep = (((1 << vStepLog) * uint64(toDistribute)) + mid) / uint64(total) // scale on remaining
|
|
tmpTotal = mid
|
|
)
|
|
for i, cnt := range s.count[:s.symbolLen] {
|
|
if s.norm[i] == notYetAssigned {
|
|
var (
|
|
end = tmpTotal + uint64(cnt)*rStep
|
|
sStart = uint32(tmpTotal >> vStepLog)
|
|
sEnd = uint32(end >> vStepLog)
|
|
weight = sEnd - sStart
|
|
)
|
|
if weight < 1 {
|
|
return errors.New("weight < 1")
|
|
}
|
|
s.norm[i] = int16(weight)
|
|
tmpTotal = end
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// validateNorm validates the normalized histogram table.
|
|
func (s *Scratch) validateNorm() (err error) {
|
|
var total int
|
|
for _, v := range s.norm[:s.symbolLen] {
|
|
if v >= 0 {
|
|
total += int(v)
|
|
} else {
|
|
total -= int(v)
|
|
}
|
|
}
|
|
defer func() {
|
|
if err == nil {
|
|
return
|
|
}
|
|
fmt.Printf("selected TableLog: %d, Symbol length: %d\n", s.actualTableLog, s.symbolLen)
|
|
for i, v := range s.norm[:s.symbolLen] {
|
|
fmt.Printf("%3d: %5d -> %4d \n", i, s.count[i], v)
|
|
}
|
|
}()
|
|
if total != (1 << s.actualTableLog) {
|
|
return fmt.Errorf("warning: Total == %d != %d", total, 1<<s.actualTableLog)
|
|
}
|
|
for i, v := range s.count[s.symbolLen:] {
|
|
if v != 0 {
|
|
return fmt.Errorf("warning: Found symbol out of range, %d after cut", i)
|
|
}
|
|
}
|
|
return nil
|
|
}
|