libdvb 0.5.0

Interface for DVB-API v5 devices in Linux
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# DiSEqC DSL

libdvb accepts SEC/DiSEqC control sequences written as a short text DSL. A
sequence is a list of single-letter commands, optionally separated by
whitespace. Pass it through `DiseqcConfig::Dsl` to apply it to a frontend.

```text
t V W200 [E0 10 38 F3] W15 T
```

## Origin

The command language is derived from VDR's `diseqc.conf` format:

<https://github.com/vdr-projects/vdr/blob/master/diseqc.conf>

## Commands

| Token       | Meaning                                                |
|-------------|--------------------------------------------------------|
| `t`         | Tone off (22kHz continuous tone off)                   |
| `T`         | Tone on (22kHz continuous tone on)                     |
| `v`         | Voltage low — 13V (vertical / right circular)          |
| `V`         | Voltage high — 18V (horizontal / left circular)        |
| `A`         | Mini-DiSEqC tone burst A                               |
| `B`         | Mini-DiSEqC tone burst B                               |
| `W<number>` | Wait `<number>` milliseconds before the next command   |
| `[hex ...]` | DiSEqC master command, 3 to 6 bytes                    |

Whitespace between commands is ignored, so `tVW200` and `t V W200` parse
identically.

## Master command hex syntax

A DiSEqC master command is written as hex bytes inside square brackets:

```text
[E0 10 38 F3]
[E01038F3]
```

Rules:

- Each byte is exactly **two** adjacent hex digits (`0-9`, `a-f`, `A-F`).
- Whitespace may appear **between** bytes.
- The command must be **3 to 6 bytes** long, matching the valid Linux DVB
  `FE_DISEQC_SEND_MASTER_CMD` range.

A typical committed-switch command looks like `[E0 10 38 Fx]`:

- byte 1 `E0` — framing (master command, no response expected)
- byte 2 `10` — address (any LNB / switch / positioner)
- byte 3 `38` — command (write to port group 0, "committed")
- byte 4 `Fx` — data, where the low nibble encodes port, voltage and tone

## Using DSL

```rust
use libdvb::{DiseqcConfig, FeDevice};

let fe = FeDevice::open_rw(0, 0)?;
let frontend_frequency_khz = fe.use_diseqc(12_320, DiseqcConfig::Dsl(
    "t V W200 [E0 10 38 F3] W15 T".to_owned(),
))?;
```

`FeDevice::use_diseqc` parses and validates the DSL internally. Its first
argument is the requested transponder frequency in MHz, and it returns the
frontend frequency in kHz. DSL, switching, and toneburst configurations retain
the requested frequency; Unicable configurations return the user-band
frequency.

## Built-in configurations

`DiseqcConfig` also provides typed configurations for common commands:

- `Switch1_0(DiseqcSwitchConfig)` - DiSEqC 1.0 committed switch, ports
  `1..=4`.
- `Switch1_1(DiseqcSwitchConfig)` - DiSEqC 1.1 uncommitted switch, ports
  `1..=16`.
- `Toneburst(ToneburstConfig)` - mini A/B tone burst.
- `Unicable1(UnicableConfig)` - EN 50494.
- `Unicable2(UnicableConfig)` - EN 50607.

```rust
use libdvb::{
    DiseqcConfig,
    DiseqcSwitchConfig,
    FeDevice,
};
use libdvb::fe::sys::{SecTone, SecVoltage};

let fe = FeDevice::open_rw(0, 0)?;
let frontend_frequency_khz = fe.use_diseqc(12_320, DiseqcConfig::Switch1_0(DiseqcSwitchConfig {
    port: 4,
    voltage: SecVoltage::V18,
    tone: SecTone::On,
}))?;
```