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ifd_enumerate.go: Eliminate unnecessary buffering 

A simplification prior to some upcoming data-access changes.
dustin/master
Dustin Oprea 2020-07-08 02:16:45 -04:00
parent 5a15f40e78
commit 4692087c1a
1 changed files with 7 additions and 19 deletions
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26
v2/ifd_enumerate.go
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@ -77,7 +77,6 @@ type byteParser struct {
byteOrder binary.ByteOrder
addressableData []byte
ifdOffset uint32
buffer *bytes.Buffer
currentOffset uint32
}
@ -91,7 +90,6 @@ func newByteParser(addressableData []byte, byteOrder binary.ByteOrder, ifdOffset
bp = &byteParser{
addressableData: addressableData,
byteOrder: byteOrder,
buffer: bytes.NewBuffer(addressableData[ifdOffset:]),
currentOffset: ifdOffset,
}
@ -111,16 +109,12 @@ func (bp *byteParser) getUint16() (value uint16, raw []byte, err error) {
// TODO(dustin): Add test
needBytes := 2
offset := 0
raw = make([]byte, needBytes)
for offset < needBytes {
n, err := bp.buffer.Read(raw[offset:])
log.PanicIf(err)
offset += n
if bp.currentOffset+needBytes >= len(bp.addressableData) {
return 0, nil, io.EOF
}
raw = addressableData[bp.currentOffset : bp.currentOffset+needBytes]
value = bp.byteOrder.Uint16(raw)
bp.currentOffset += uint32(needBytes)
@ -141,17 +135,13 @@ func (bp *byteParser) getUint32() (value uint32, raw []byte, err error) {
// TODO(dustin): Add test
needBytes := 4
offset := 0
raw = make([]byte, needBytes)
for offset < needBytes {
n, err := bp.buffer.Read(raw[offset:])
log.PanicIf(err)
offset += n
if bp.currentOffset+needBytes >= len(bp.addressableData) {
return 0, nil, io.EOF
}
value = bp.byteOrder.Uint32(raw)
raw = addressableData[bp.currentOffset : bp.currentOffset+needBytes]
value = bp.byteOrder.Uint16(raw)
bp.currentOffset += uint32(needBytes)
@ -168,7 +158,6 @@ func (bp *byteParser) CurrentOffset() uint32 {
// containers in the EXIF blob.
type IfdEnumerate struct {
exifData []byte
buffer *bytes.Buffer
byteOrder binary.ByteOrder
tagIndex *TagIndex
ifdMapping *exifcommon.IfdMapping
@ -179,7 +168,6 @@ type IfdEnumerate struct {
func NewIfdEnumerate(ifdMapping *exifcommon.IfdMapping, tagIndex *TagIndex, exifData []byte, byteOrder binary.ByteOrder) *IfdEnumerate {
return &IfdEnumerate{
exifData: exifData,
buffer: bytes.NewBuffer(exifData),
byteOrder: byteOrder,
ifdMapping: ifdMapping,
tagIndex: tagIndex,