112 lines
3.3 KiB
Nim
112 lines
3.3 KiB
Nim
## A simple MIDI transpose LV2 plugin
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import std/math
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#import std/strformat
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#import std/strutils
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import nymph/[atom, core, midi, util, urid]
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import nymph/atom/util
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const PluginUri = "urn:nymph:examples:miditranspose"
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type
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PluginPort {.pure.} = enum
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Input, Output, Transposition
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MidiTransposePlugin = object
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input: ptr AtomSequence
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output: ptr AtomSequence
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transposition: ptr cfloat
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map: ptr UridMap
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midi_urid: Urid
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MidiEvent = object
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size: uint32
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frames: int64
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data: ptr UncheckedArray[byte]
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proc instantiate(descriptor: ptr Lv2Descriptor; sampleRate: cdouble;
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bundlePath: cstring; features: ptr UncheckedArray[ptr Lv2Feature]):
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Lv2Handle {.cdecl.} =
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let plug: ptr MidiTransposePlugin = createShared(MidiTransposePlugin)
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plug.map = cast[ptr UridMap](lv2FeaturesData(features, lv2UridMap))
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if plug.map.isNil:
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freeShared(plug)
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return nil
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plug.midi_urid = plug.map.map(plug.map.handle, lv2MidiMidiEvent)
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return cast[Lv2Handle](plug)
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proc connectPort(instance: Lv2Handle; port: cuint;
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dataLocation: pointer) {.cdecl.} =
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let plug = cast[ptr MidiTransposePlugin](instance)
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case cast[PluginPort](port)
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of PluginPort.Input:
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plug.input = cast[ptr AtomSequence](dataLocation)
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of PluginPort.Output:
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plug.output = cast[ptr AtomSequence](dataLocation)
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of PluginPort.Transposition:
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plug.transposition = cast[ptr cfloat](dataLocation)
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proc activate(instance: Lv2Handle) {.cdecl.} =
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discard
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proc run(instance: Lv2Handle; nSamples: cuint) {.cdecl.} =
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let plug = cast[ptr MidiTransposePlugin](instance)
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let outCapacity = plug.output.atom.size
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atomSequenceClear(plug.output)
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plug.output.atom.type = plug.input.atom.type
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if not atomSequenceIsEmpty(plug.input):
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#echo &"Event sequence size: {plug.input.atom.size}"
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let noteOffset = clamp(floor(plug.transposition[] + 0.5), -12, 12).uint8
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for ev in plug.input:
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if ev.body.`type` == plug.midi_urid:
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var msg = cast[ptr UncheckedArray[uint8]](atomContents(AtomEvent, ev))
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#echo &"0x{toHex(msg[0], 2)} 0x{toHex(msg[1], 2)} 0x{toHex(msg[2], 2)}"
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case midiGetMessageType(msg[]):
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of midiMsgNoteOff, midiMsgNoteOn, midiMsgNotePressure:
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msg[1] = clamp(msg[1] + noteOffset, 0, 127).uint8
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else:
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discard
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discard atomSequenceAppendEvent(plug.output, outCapacity, ev)
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proc deactivate(instance: Lv2Handle) {.cdecl.} =
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discard
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proc cleanup(instance: Lv2Handle) {.cdecl.} =
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freeShared(cast[ptr MidiTransposePlugin](instance))
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proc extensionData(uri: cstring): pointer {.cdecl.} =
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return nil
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proc NimMain() {.cdecl, importc.}
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proc lv2Descriptor(index: cuint): ptr Lv2Descriptor {.
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cdecl, exportc, dynlib, extern: "lv2_descriptor".} =
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NimMain()
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if index == 0:
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result = createShared(Lv2Descriptor)
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result.uri = cstring(PluginUri)
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result.instantiate = instantiate
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result.connectPort = connectPort
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result.activate = activate
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result.run = run
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result.deactivate = deactivate
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result.cleanup = cleanup
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result.extensionData = extensionData
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