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109 lines
2.3 KiB
Go
109 lines
2.3 KiB
Go
package repeater
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import (
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"errors"
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"fmt"
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"github.com/tehmaze/go-dmr/bit"
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"github.com/tehmaze/go-dmr/bptc"
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"github.com/tehmaze/go-dmr/dmr"
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"github.com/tehmaze/go-dmr/fec"
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"github.com/tehmaze/go-dmr/ipsc"
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)
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type LC struct {
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CallType uint8
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DstID, SrcID uint32
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}
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func (r *Repeater) HandleTerminatorWithLC(p *ipsc.Packet) error {
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r.DataCallEnd(p)
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var (
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err error
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payload = make([]byte, 12)
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)
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if err = bptc.Process(dmr.ExtractInfoBits(p.PayloadBits), payload); err != nil {
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return err
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}
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// CRC mask to the checksum. See DMR AI. spec. page 143.
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payload[9] ^= 0x99
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payload[10] ^= 0x99
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payload[11] ^= 0x99
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var lc *LC
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if lc, err = r.lcDecodeFullLC(payload); err != nil {
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return err
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}
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fmt.Printf(" lc: %d -> %d\n", lc.SrcID, lc.DstID)
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return nil
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}
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func (r *Repeater) HandleVoiceLCHeader(p *ipsc.Packet) error {
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r.DataCallEnd(p)
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var (
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err error
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payload = make([]byte, 12)
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)
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if err = bptc.Process(dmr.ExtractInfoBits(p.PayloadBits), payload); err != nil {
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return err
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}
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// CRC mask to the checksum. See DMR AI. spec. page 143
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for i := 9; i < 12; i++ {
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payload[i] ^= 0x99
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}
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var lc *LC
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if lc, err = r.lcDecodeFullLC(payload); err != nil {
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return err
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}
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fmt.Printf(" lc: %d -> %d\n", lc.SrcID, lc.DstID)
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return nil
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}
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func (r *Repeater) lcDecode(payload []byte) (*LC, error) {
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if payload[0]&bit.B10000000 > 0 {
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return nil, errors.New("dmr/lc: protect flag is not 0")
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}
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if payload[1] != 0 {
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return nil, errors.New("dmr/lc: feature set ID is not 0")
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}
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lc := &LC{}
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switch payload[0] & bit.B00111111 {
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case 3:
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lc.CallType = ipsc.CallTypePrivate
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case 0:
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lc.CallType = ipsc.CallTypeGroup
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default:
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return nil, fmt.Errorf("dmr/lc: invalid FCLO; unknown call type %#02x", payload[0]&bit.B00111111)
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}
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lc.DstID = uint32(payload[3])<<16 | uint32(payload[4])<<8 | uint32(payload[5])
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lc.SrcID = uint32(payload[6])<<16 | uint32(payload[7])<<8 | uint32(payload[8])
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return lc, nil
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}
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func (r *Repeater) lcDecodeFullLC(payload []byte) (*LC, error) {
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var (
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err error
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syndrome = fec.RS_12_9_Poly{}
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)
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if err = fec.RS_12_9_CalcSyndrome(payload, &syndrome); err != nil {
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return nil, err
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}
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if fec.RS_12_9_CheckSyndrome(&syndrome) {
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if _, err = fec.RS_12_9_Correct(payload, &syndrome); err != nil {
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return nil, err
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}
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}
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return r.lcDecode(payload)
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}
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