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87 lines
3.0 KiB
Go
87 lines
3.0 KiB
Go
// Package dmr contains generic message structures for the Digital Mobile Radio standard
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package dmr
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import (
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"fmt"
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"github.com/pd0mz/go-dmr/bit"
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)
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const (
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InfoPartBits = 98
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InfoBits = InfoPartBits * 2
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SlotPartBits = 10
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SlotBits = SlotPartBits * 2
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PayloadPartBits = InfoPartBits + SlotPartBits
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PayloadBits = PayloadPartBits * 2
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SignalBits = 48
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BurstBits = PayloadBits + SignalBits
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)
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// Table 9.2: SYNC Patterns
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var SYNCPatterns = map[string]struct {
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ControlMode string
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PDU string
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}{
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"\x07\x05\x05\x0f\x0d\x07\x0d\x0f\x07\x05\x0f\x07": {"BS sourced", "voice"},
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"\x0d\x0f\x0f\x05\x07\x0d\x07\x05\x0d\x0f\x05\x0d": {"BS sourced", "data"},
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"\x07\x0f\x07\x0d\x05\x0d\x0d\x05\x07\x0d\x0f\x0d": {"MS sourced", "voice"},
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"\x0d\x05\x0d\x07\x0f\x07\x07\x0f\x0d\x07\x05\x07": {"MS sourced", "data"},
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"\x07\x07\x0d\x05\x05\x0f\x07\x0d\x0f\x0d\x07\x07": {"MS sourced", "rc sync"},
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"\x05\x0d\x05\x07\x07\x0f\x07\x07\x05\x07\x0f\x0f": {"TDMA direct mode time slot 1", "voice"},
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"\x0f\x07\x0f\x0d\x0d\x05\x0d\x0d\x0f\x0d\x05\x05": {"TDMA direct mode time slot 1", "data"},
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"\x07\x0d\x0f\x0f\x0d\x05\x0f\x05\x05\x0d\x05\x0f": {"TDMA direct mode time slot 2", "voice"},
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"\x0d\x07\x05\x05\x07\x0f\x05\x0f\x0f\x07\x0f\x05": {"TDMA direct mode time slot 2", "data"},
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"\x0d\x0d\x07\x0f\x0f\x05\x0d\x07\x05\x07\x0d\x0d": {"Reserved SYNC pattern", "reserved"},
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}
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// Burst contains data from a single burst, see 4.2.2 Burst and frame structure
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type Burst struct {
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bits bit.Bits
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}
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func NewBurst(raw []byte) (*Burst, error) {
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if len(raw)*8 != BurstBits {
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return nil, fmt.Errorf("dmr: expected %d bits, got %d", BurstBits, len(raw)*8)
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}
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b := &Burst{}
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b.bits = bit.NewBits(raw)
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return b, nil
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}
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// Info returns the 196 bits of info in the burst. The data is usually BPTC(196, 96) encoded.
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func (b *Burst) Info() bit.Bits {
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// The info is contained in bits 0..98 and 166..216 for a total of 196 bits
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var n = make(bit.Bits, InfoBits)
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copy(n[0:InfoPartBits], b.bits[0:InfoPartBits])
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copy(n[InfoPartBits:InfoBits], b.bits[InfoPartBits+SignalBits+SlotBits:BurstBits])
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return n
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}
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// Payload returns the 216 bits of payload in the burst.
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func (b *Burst) Payload() bit.Bits {
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// The payload is contained in bits 0..108 and 156..264 for a total of 216 bits
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var p = make(bit.Bits, PayloadBits)
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copy(p[0:PayloadPartBits], b.bits[0:PayloadPartBits])
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copy(p[PayloadPartBits:PayloadBits], b.bits[PayloadPartBits+SignalBits:BurstBits])
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return p
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}
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// Signal returns the 48 bits of signal or SYNC information in the burst.
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func (b *Burst) Signal() bit.Bits {
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// The signal bits are contained in bits 108..156 for a total of 48 bits
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var s = make(bit.Bits, SignalBits)
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copy(s, b.bits[PayloadPartBits:PayloadPartBits+SignalBits])
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return s
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}
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func (b *Burst) SlotType() uint32 {
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/* The slottype is 20 bits, starting after the payload info */
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var s uint32
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for i := InfoPartBits; i < InfoPartBits+SlotBits; i++ {
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var shift = uint32(20 - (i - InfoPartBits))
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s = s | uint32(b.bits[i]<<shift)
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}
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return s
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}
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