Cleanup delta compression

This commit is contained in:
Andrew Gutekanst
2020-03-08 19:07:02 -04:00
parent 8e53b6cc63
commit 343333217f
4 changed files with 2 additions and 85 deletions

View File

@@ -1,11 +1,10 @@
package deltacomp
import (
"io"
"bytes"
"io"
)
func checkReadUint8(r *bytes.Reader) (uint8, error) {
b, err := r.ReadByte()
if err != nil {
@@ -73,7 +72,7 @@ func ApplyDataDiff(diff []byte, baseData []byte) []byte {
// No more data
break
}
differentCount -= 1
differentCount--
// Apply the patch bytes.
for i := 0; i < differentCount; i++ {
@@ -90,85 +89,3 @@ func ApplyDataDiff(diff []byte, baseData []byte) []byte {
return baseCopy
}
/*
func checkReadUint8(bf *byteframe.ByteFrame) (uint8, error) {
if len(bf.DataFromCurrent()) >= 1 {
return bf.ReadUint8(), nil
}
return 0, errors.New("Not enough data")
}
func checkReadUint16(bf *byteframe.ByteFrame) (uint16, error) {
if len(bf.DataFromCurrent()) >= 2 {
return bf.ReadUint16(), nil
}
return 0, errors.New("Not enough data")
}
func readCount(bf *byteframe.ByteFrame) (int, error) {
var count int
count8, err := checkReadUint8(bf)
if err != nil {
return 0, err
}
count = int(count8)
if count == 0 {
count16, err := checkReadUint16(bf)
if err != nil {
return 0, err
}
count = int(count16)
}
return int(count), nil
}
// ApplyDataDiff applies a delta data diff patch onto given base data.
func ApplyDataDiff(diff []byte, baseData []byte) []byte {
// Make a copy of the base data to return,
// (probably just make this modify the given slice in the future).
baseCopy := make([]byte, len(baseData))
copy(baseCopy, baseData)
patch := byteframe.NewByteFrameFromBytes(diff)
// The very first matchCount is +1 more than it should be, so we start at -1.
dataOffset := -1
for {
// Read the amount of matching bytes.
matchCount, err := readCount(patch)
if err != nil {
// No more data
break
}
dataOffset += matchCount
// Read the amount of differing bytes.
differentCount, err := readCount(patch)
if err != nil {
// No more data
break
}
differentCount -= 1
// Apply the patch bytes.
for i := 0; i < differentCount; i++ {
b, err := checkReadUint8(patch)
if err != nil {
panic("Invalid or misunderstood patch format!")
}
baseCopy[dataOffset+i] = b
}
dataOffset += differentCount - 1
}
return baseCopy
}
*/