99 lines
3.0 KiB
Nim
99 lines
3.0 KiB
Nim
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## A simple MIDI event processor LV2 plugin
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import std/[math, strformat, 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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proc printFeatures(features: ptr UncheckedArray[ptr Lv2Feature]) =
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if features != nil:
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var i = 0
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while true:
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let feature = features[i]
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if feature == nil:
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break
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echo &"URI: {feature[].uri}"
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echo &"Data: {cast[int](feature[].data)}"
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inc i
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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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printFeatures(features)
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let amp: ptr MidiTransposePlugin = createShared(MidiTransposePlugin)
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amp.map = cast[ptr UridMap](lv2FeaturesData(features, lv2UridMap))
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assert amp.map != nil
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amp.midi_urid = amp.map[].map(amp.map[].handle, lv2MidiMidiEvent)
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echo &"{lv2MidiMidiEvent} = {amp.midi_urid.int}"
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return cast[Lv2Handle](amp)
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proc connectPort(instance: Lv2Handle; port: cuint;
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dataLocation: pointer) {.cdecl.} =
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let amp = cast[ptr MidiTransposePlugin](instance)
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case cast[PluginPort](port)
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of PluginPort.Input:
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amp.input = cast[ptr AtomSequence](dataLocation)
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of PluginPort.Output:
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amp.output = cast[ptr AtomSequence](dataLocation)
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of PluginPort.Transposition:
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amp.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 amp = cast[ptr MidiTransposePlugin](instance)
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if amp.input.atom.size > 8:
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for ev in items(amp.input):
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if Urid(ev.body.`type`) == amp.midi_urid:
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# TODO
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var msg = cast[ptr UncheckedArray[uint8]](ev.body.addr + 1)
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echo &"0x{toHex(msg[0], 2)} 0x{toHex(msg[1], 2)} 0x{toHex(msg[2], 2)}"
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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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