feat: wrap LV2_Lib_Descriptor

Use lv2_lib_descriptor in amp example plugin to improve lib memory handling

Signed-off-by: Christopher Arndt <chris@chrisarndt.de>

examples/amp_plugin.nim

@@ -60,7 +60,7 @@ proc connectPort(instance: Lv2Handle; port: cuint;
 
 proc activate(instance: Lv2Handle) {.cdecl.} =
     let plug = cast[ptr AmpPlugin](instance)
-    plug.log.note("nymph amp plugin activated.")
+    plug.log.note("nymph amp LV2 plugin activated.")
 
 
 proc run(instance: Lv2Handle; nSamples: cuint) {.cdecl.} =
@@ -71,12 +71,12 @@ proc run(instance: Lv2Handle; nSamples: cuint) {.cdecl.} =
 
 proc deactivate(instance: Lv2Handle) {.cdecl.} =
     let plug = cast[ptr AmpPlugin](instance)
-    plug.log.note("nymph amp plugin deactivated.")
+    plug.log.note("nymph amp LV2 plugin deactivated.")
 
 
-proc cleanup(instance: Lv2Handle) {.cdecl.} =
+proc cleanupInstance(instance: Lv2Handle) {.cdecl.} =
     let plug = cast[ptr AmpPlugin](instance)
-    plug.log.note("De-allocating nymph amp plugin instance.")
+    plug.log.note("nymph amp LV2 plugin instance will be de-allocated.")
     freeShared(cast[ptr AmpPlugin](instance))
 
 
@@ -85,26 +85,44 @@ proc extensionData(uri: cstring): pointer {.cdecl.} =
 
 
 proc NimMain() {.cdecl, importc.}
+proc NimDestroyGlobals() {.cdecl, importc.}
 
 
-let descriptor = Lv2Descriptor(
+let pluginDescriptor = Lv2Descriptor(
     uri: cstring(PluginUri),
     instantiate: instantiate,
     connectPort: connectPort,
     activate: activate,
     run: run,
     deactivate: deactivate,
-    cleanup: cleanup,
+    cleanup: cleanupInstance,
     extensionData: extensionData,
 )
 
-proc lv2Descriptor(index: cuint): ptr Lv2Descriptor {.
-                   cdecl, exportc, dynlib, extern: "lv2_descriptor".} =
 
-    echo fmt"nymph am plugin descriptor #{index} requested"
+proc cleanupLib(handle: Lv2LibHandle) {.cdecl.} =
+    echo "Cleaning up nymph amp library globals."
+    NimDestroyGlobals()
 
+
+proc getPlugin(handle: Lv2Libhandle, index: cuint): ptr Lv2Descriptor {.cdecl.} =
     if index == 0:
-        NimMain()
-        return addr(descriptor)
+        echo &"Providing nymph amp LV2 plugin descriptor #{index} to host."
+        return addr(pluginDescriptor)
 
     return nil
+
+
+let libDescriptor = Lv2LibDescriptor(
+    handle: cast[Lv2LibHandle](nil),
+    size: sizeof(Lv2LibDescriptor).cuint,
+    cleanup: cleanupLib,
+    getPlugin: getPlugin,
+)
+
+
+proc lv2LibDescriptor(bundlePath: cstring, features: ptr UncheckedArray[ptr Lv2Feature]): ptr Lv2LibDescriptor {.
+                      cdecl, dynlib, exportc: "lv2_lib_descriptor".} =
+    NimMain()
+    echo "Providing nymph amp LV2 library descriptor to host."
+    return addr(libDescriptor)

nymph.nimble

@@ -11,7 +11,7 @@ srcDir        = "src"
 
 # Dependencies
 
-requires "nim >= 2.0"
+requires "nim >= 2.2.2"
 
 # Custom tasks
 
@@ -89,7 +89,7 @@ task lv2lint, "Run lv2lint check on given example plugin":
     let ex = getExample("lv2lint")
 
     if fileExists(ex.dll):
-        exec(&"lv2lint -s NimMain -s NimDestroyGlobals -I \"{ex.bundle}\" \"{ex.uri}\"")
+        exec(&"lv2lint -s NimMain -s NimDestroyGlobals -s lv2_lib_descriptor -I \"{ex.bundle}\" \"{ex.uri}\"")
     else:
         echo &"Example '{ex.name}' shared library not found. Use task 'build_ex' to build it."
 

src/nymph/core.nim

@@ -95,27 +95,29 @@ const
 type
     Lv2Handle* = distinct pointer
 
-type Lv2Feature* = object
+    Lv2LibHandle* = distinct pointer
+
+    Lv2Feature* = object
         uri*: cstring
         data*: pointer
 
-type Lv2Descriptor* = object
+    Lv2Descriptor* = object
         uri*: cstring
-
         instantiate*: proc(descriptor: ptr Lv2Descriptor, sampleRate: cdouble, bundlePath: cstring,
                            features: ptr UncheckedArray[ptr Lv2Feature]): Lv2Handle {.cdecl.}
-
         connectPort*: proc(instance: Lv2Handle, port: cuint, dataLocation: pointer) {.cdecl.}
-
         activate*: proc(instance: Lv2Handle) {.cdecl.}
-
         run*: proc(instance: Lv2Handle, sampleCount: cuint) {.cdecl.}
-
         deactivate*: proc(instance: Lv2Handle) {.cdecl.}
-
         cleanup*: proc(instance: Lv2Handle) {.cdecl.}
-
         extensionData*: proc(uri: cstring): pointer {.cdecl.}
 
-type lv2Descriptor* = proc(index: cuint): ptr Lv2Descriptor {.cdecl.}
+    Lv2LibDescriptor* = object
+        handle*: Lv2LibHandle
+        size*: cuint
+        cleanup*: proc(handle: Lv2LibHandle) {.cdecl.}
+        getPlugin*: proc(handle: Lv2LibHandle, index: cuint): ptr Lv2Descriptor {.cdecl.}
 
+    lv2Descriptor* = proc(index: cuint): ptr Lv2Descriptor {.cdecl.}
+
+    lv2LibDescriptor* = proc(bundle_path: cstring, features: ptr UncheckedArray[ptr Lv2Feature]): LV2_Lib_Descriptor {.cdecl.}