mirror of
https://github.com/wader/fq.git
synced 2024-11-25 23:13:19 +03:00
2fc0a71a47
Move scalar into own package. Split scalar code into decode related scalar code (that reads etc) and scalar code that just transform the scalar value. Use a scalar.Mapper interface instead of just a function. Make mappers, assert and validat impement the interface.
64 lines
2.0 KiB
Go
64 lines
2.0 KiB
Go
package ogg
|
|
|
|
import (
|
|
"bytes"
|
|
|
|
"github.com/wader/fq/format"
|
|
"github.com/wader/fq/format/registry"
|
|
"github.com/wader/fq/pkg/checksum"
|
|
"github.com/wader/fq/pkg/decode"
|
|
"github.com/wader/fq/pkg/scalar"
|
|
)
|
|
|
|
func init() {
|
|
registry.MustRegister(decode.Format{
|
|
Name: format.OGG_PAGE,
|
|
Description: "OGG page",
|
|
DecodeFn: pageDecode,
|
|
})
|
|
}
|
|
|
|
func pageDecode(d *decode.D, in interface{}) interface{} {
|
|
p := format.OggPageOut{}
|
|
startPos := d.Pos()
|
|
|
|
d.Endian = decode.LittleEndian
|
|
|
|
d.FieldUTF8("capture_pattern", 4, d.AssertStr("OggS"))
|
|
d.FieldU8("version", d.AssertU(0))
|
|
d.FieldU5("unused_flags")
|
|
p.IsLastPage = d.FieldBool("last_page")
|
|
p.IsFirstPage = d.FieldBool("first_page")
|
|
p.IsContinuedPacket = d.FieldBool("continued_packet")
|
|
d.FieldU64("granule_position")
|
|
p.StreamSerialNumber = uint32(d.FieldU32("bitstream_serial_number"))
|
|
p.SequenceNo = uint32(d.FieldU32("page_sequence_no"))
|
|
d.FieldU32("crc", scalar.Hex)
|
|
pageSegments := d.FieldU8("page_segments")
|
|
var segmentTable []uint64
|
|
d.FieldArray("segment_table", func(d *decode.D) {
|
|
for i := uint64(0); i < pageSegments; i++ {
|
|
segmentTable = append(segmentTable, d.FieldU8("segment_size"))
|
|
}
|
|
})
|
|
d.FieldArray("segments", func(d *decode.D) {
|
|
for _, ss := range segmentTable {
|
|
bs, err := d.FieldRawLen("segment", int64(ss)*8).Bytes()
|
|
if err != nil {
|
|
d.IOPanic(err, "d.BitBufRange segment")
|
|
}
|
|
p.Segments = append(p.Segments, bs)
|
|
}
|
|
})
|
|
endPos := d.Pos()
|
|
|
|
pageChecksumValue := d.FieldGet("crc")
|
|
pageCRC := &checksum.CRC{Bits: 32, Table: checksum.Poly04c11db7Table}
|
|
d.MustCopy(pageCRC, d.BitBufRange(startPos, pageChecksumValue.Range.Start-startPos)) // header before checksum
|
|
d.MustCopy(pageCRC, bytes.NewReader([]byte{0, 0, 0, 0})) // zero checksum bits
|
|
d.MustCopy(pageCRC, d.BitBufRange(pageChecksumValue.Range.Stop(), endPos-pageChecksumValue.Range.Stop())) // rest of page
|
|
_ = pageChecksumValue.TryScalarFn(d.ValidateUBytes(pageCRC.Sum(nil)))
|
|
|
|
return p
|
|
}
|