feat: add simple sine wave generator client example

examples/jacket_simple_client.nim

@@ -0,0 +1,104 @@
+import std/[logging, math, os]
+import signal
+import jacket
+
+var jclient: ClientTPtr
+var out1: PortTPtr
+var status: cint
+var log = newConsoleLogger(when defined(release): lvlInfo else: lvlDebug)
+
+type
+    SampleT = DefaultAudioSampleT
+    JackBufferPtr = ptr UncheckedArray[SampleT]
+const
+    tableSize = 4096
+    sineFreq = 440.0
+    twoPi = Pi * 2.0
+
+type
+    SineOsc = object
+        waveform: array[0..tableSize, float]
+        phase: float
+        idxInc: float
+    SineOscPtr = ref SineOsc
+
+proc initSineOsc(sr: float, freq: float): SineOsc =
+    let phsInc = twoPi / tableSize
+    var phase = 0.0
+    
+    for i in 0 ..< tableSize:
+        result.waveform[i] = sin(phase)
+        phase += phsInc
+
+    result.phase = 0.0
+    result.idxInc = tableSize / sr * freq
+
+proc tick(osc: SineOscPtr): float =
+    result = osc.waveform[int(osc.phase)]
+    osc.phase += osc.idxInc;
+    
+    if osc.phase >= tableSize:
+        osc.phase -= tableSize
+
+proc errorCb(msg: cstring) {.cdecl.} =
+    # Suppress verbose JACK error messages when server is not available by
+    # default. Pass ``lvlAll`` when creating the logger to enable them.
+    debug "JACK error: " & $msg
+
+proc cleanup(sig: cint = 0) {.noconv.} =
+    debug "Cleaning up..."
+    
+    if jclient != nil:
+        discard jclient.deactivate()
+        discard jclient.clientClose()
+        jclient = nil
+
+    quit QuitSuccess
+
+proc shutdownCb(arg: pointer = nil) {.cdecl.} =
+    debug "Server has shut down"
+    cleanup()
+
+proc process(nFrames: NFramesT, arg: pointer): cint {.cdecl.} = 
+    var outbuf = cast[JackBufferPtr](portGetBuffer(out1, nFrames))
+    let osc = cast[SineOscPtr](arg)
+
+    for i in 0 ..< nFrames:
+        outbuf[i] = osc.tick() * 0.2
+
+    return 0
+
+addHandler(log)
+
+# create JACK client
+setErrorFunction(errorCb)
+jclient = clientOpen("jacket_port_register", NoStartServer.ord or UseExactName.ord, status.addr)
+debug "Server status: " & $status
+
+if jclient == nil:
+    error getJackStatusErrorString(status)
+    quit 1
+
+let sampleRate =(float) jclient.getSampleRate()
+var osc = initSineOsc(sampleRate, sineFreq)
+
+
+when defined(windows):
+    setSignalProc(cleanup, SIGABRT, SIGINT, SIGTERM)
+else:
+    setSignalProc(cleanup, SIGABRT, SIGHUP, SIGINT, SIGQUIT, SIGTERM)
+
+if jclient.setProcessCallback(process, osc.addr) != 0:
+    error "Could not set process callback function."
+    cleanup()
+
+jclient.onShutdown(shutdownCb, nil)
+
+out1 = jclient.portRegister("out_1", JACK_DEFAULT_AUDIO_TYPE, PortIsOutput.ord, 0)
+
+if jclient.activate() == 0:
+    #  keep running until the Ctrl+C
+    while true:
+        sleep(50)
+
+cleanup() # normally not reached