From 9bb9321dcb2113dbdd1b594f33d37c8435e15a64 Mon Sep 17 00:00:00 2001
From: Christopher Arndt <chris@chrisarndt.de>
Date: Tue, 21 May 2024 18:09:40 +0200
Subject: [PATCH] Make MIDI transpose example functional

Signed-off-by: Christopher Arndt <chris@chrisarndt.de>
---
 examples/miditranspose.nim | 47 ++++++++++++++++-------------
 src/nymph/atom.nim         | 61 ++++++++++++++------------------------
 src/nymph/atom/util.nim    | 11 ++-----
 src/nymph/ptrmath.nim      |  6 ++++
 src/nymph/urid.nim         | 14 +++------
 src/nymph/util.nim         |  2 +-
 6 files changed, 63 insertions(+), 78 deletions(-)
 create mode 100644 src/nymph/ptrmath.nim

diff --git a/examples/miditranspose.nim b/examples/miditranspose.nim
index eec3ba5..df5c14c 100644
--- a/examples/miditranspose.nim
+++ b/examples/miditranspose.nim
@@ -1,6 +1,8 @@
-## A simple MIDI event processor LV2 plugin
+## A simple MIDI transpose LV2 plugin
 
-import std/[math, strformat, strutils]
+import std/math
+#import std/strformat
+#import std/strutils
 import nymph/[atom, core, midi, util, urid]
 import nymph/atom/util
 
@@ -18,27 +20,17 @@ type
         midi_urid: Urid
 
 
-proc printFeatures(features: ptr UncheckedArray[ptr Lv2Feature]) =
-    if features != nil:
-        var i = 0
-        while true:
-            let feature = features[i]
-            if feature == nil:
-                break
-            echo &"URI: {feature[].uri}"
-            echo &"Data: {cast[int](feature[].data)}"
-            inc i
-
-
 proc instantiate(descriptor: ptr Lv2Descriptor; sampleRate: cdouble;
                  bundlePath: cstring; features: ptr UncheckedArray[ptr Lv2Feature]):
                  Lv2Handle {.cdecl.} =
-    printFeatures(features)
     let amp: ptr MidiTransposePlugin = createShared(MidiTransposePlugin)
     amp.map = cast[ptr UridMap](lv2FeaturesData(features, lv2UridMap))
-    assert amp.map != nil
+
+    if amp.map == nil:
+        return nil
+
     amp.midi_urid = amp.map[].map(amp.map[].handle, lv2MidiMidiEvent)
-    echo &"{lv2MidiMidiEvent} = {amp.midi_urid.int}"
+
     return cast[Lv2Handle](amp)
 
 
@@ -53,18 +45,33 @@ proc connectPort(instance: Lv2Handle; port: cuint;
     of PluginPort.Transposition:
         amp.transposition = cast[ptr cfloat](dataLocation)
 
+
 proc activate(instance: Lv2Handle) {.cdecl.} =
     discard
 
 
 proc run(instance: Lv2Handle; nSamples: cuint) {.cdecl.} =
     let amp = cast[ptr MidiTransposePlugin](instance)
+    let outCapacity = amp.output.atom.size
+    atomSequenceClear(amp.output)
+    amp.output.atom.type = amp.input.atom.type
+
     if amp.input.atom.size > 8:
+        #echo &"Event sequence size: {amp.input.atom.size}"
+
         for ev in items(amp.input):
             if Urid(ev.body.`type`) == amp.midi_urid:
-                # TODO
-                var msg = cast[ptr UncheckedArray[uint8]](ev.body.addr + 1)
-                echo &"0x{toHex(msg[0], 2)} 0x{toHex(msg[1], 2)} 0x{toHex(msg[2], 2)}"
+                var msg = cast[ptr UncheckedArray[uint8]](atomContents(AtomEvent, ev))
+                #echo &"0x{toHex(msg[0], 2)} 0x{toHex(msg[1], 2)} 0x{toHex(msg[2], 2)}"
+
+                case midiGetMessageType(msg[]):
+                of midiMsgNoteOff, midiMsgNoteOn, midiMsgNotePressure:
+                    let noteOffset = clamp(floor(amp.transposition[] + 0.5), -12, 12).uint8
+                    msg[1] = clamp(msg[1] + noteOffset, 0, 127).uint8
+                else:
+                    discard
+
+                discard atomSequenceAppendEvent(amp.output, outCapacity, ev)
 
 
 proc deactivate(instance: Lv2Handle) {.cdecl.} =
diff --git a/src/nymph/atom.nim b/src/nymph/atom.nim
index 4a19e19..be316f0 100644
--- a/src/nymph/atom.nim
+++ b/src/nymph/atom.nim
@@ -6,6 +6,8 @@
 ## See <http://lv2plug.in/ns/ext/atom> for details.
 ##
 
+import ptrmath
+
 const
     lv2AtomBaseUri ="http://lv2plug.in/ns/ext/atom"
     lv2AtomPrefix = lv2AtomBaseUri & "#"
@@ -51,29 +53,12 @@ const
 template atomContents*(`type`, atom: untyped): pointer =
     cast[ptr uint8](atom) + sizeof(`type`)
 
-#[
-{.push header: "lv2/atom/atom.h".}
-
-var atomReferenceType* {.importc: "LV2_ATOM_REFERENCE_TYPE".}: int
-
-##
-## Const version of LV2_ATOM_CONTENTS.
-##
-proc atomContentsConst*(`type`: untyped; atom: untyped) {.importc: "LV2_ATOM_CONTENTS_CONST".}
-
 ##
 ## Return a pointer to the body of an Atom.  The "body" of an atom is the
-## data just past the LV2_Atom head (i.e. the same offset for all types).
+## data just past the Atom head (i.e. the same offset for all types).
 ##
-proc atomBody*(atom: untyped) {.importc: "LV2_ATOM_BODY".}
-
-##
-## Const version of LV2_ATOM_BODY.
-##
-proc atomBodyConst*(atom: untyped) {.importc: "LV2_ATOM_BODY_CONST".}
-
-{.pop.}
-]#
+template atomBody*(atom: untyped): pointer =
+    atomContents(Atom, atom)
 
 type
     ## The header of an atom:Atom.
@@ -81,35 +66,35 @@ type
         size*: uint32  ## Size in bytes, not including type and size.
         `type`*: uint32  ## of this atom (mapped URI).
 
-    ## An atom:Int or atom:Bool.  May be cast to LV2_Atom.
+    ## An atom:Int or atom:Bool.  May be cast to Atom.
     AtomInt* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         body*: int32  ## Integer value.
 
-    ## An atom:Long.  May be cast to LV2_Atom.
+    ## An atom:Long.  May be cast to Atom.
     AtomLong* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         body*: int64  ## Integer value.
 
-    ## An atom:Float.  May be cast to LV2_Atom.
+    ## An atom:Float.  May be cast to Atom.
     AtomFloat* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         body*: cfloat  ## Floating point value.
 
-    ## An atom:Double.  May be cast to LV2_Atom.
+    ## An atom:Double.  May be cast to Atom.
     AtomDouble* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         body*: cdouble  ## Floating point value.
 
-    ## An atom:Bool.  May be cast to LV2_Atom.
+    ## An atom:Bool.  May be cast to Atom.
     AtomBool* = distinct AtomInt
 
-    ## An atom:URID.  May be cast to LV2_Atom.
+    ## An atom:URID.  May be cast to Atom.
     AtomUrid* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         body*: uint32  ## URID.
 
-    ## An atom:String.  May be cast to LV2_Atom.
+    ## An atom:String.  May be cast to Atom.
     AtomString* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         ## Contents (a null-terminated UTF-8 string) follow here.
@@ -120,12 +105,12 @@ type
         lang*: uint32  ## Language URID.
         ## Contents (a null-terminated UTF-8 string) follow here.
 
-    ## An atom:Literal.  May be cast to LV2_Atom.
+    ## An atom:Literal.  May be cast to Atom.
     AtomLiteral* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         body*: AtomLiteralBody  ## Body.
 
-    ## An atom:Tuple.  May be cast to LV2_Atom.
+    ## An atom:Tuple.  May be cast to Atom.
     AtomTuple* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         ## Contents (a series of complete atoms) follow here.
@@ -136,7 +121,7 @@ type
         childType*: uint32  ## The of each element in the vector.
         ## Contents (a series of packed atom bodies) follow here.
 
-    ## An atom:Vector.  May be cast to LV2_Atom.
+    ## An atom:Vector.  May be cast to Atom.
     AtomVector* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         body*: AtomVectorBody  ## Body.
@@ -148,23 +133,23 @@ type
         value*: Atom  ## Value atom header.
         ## Value atom body follows here.
 
-    ## An atom:Property.  May be cast to LV2_Atom.
+    ## An atom:Property.  May be cast to Atom.
     AtomProperty* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         body*: AtomPropertyBody  ## Body.
 
-    ## The body of an atom:Object. May be cast to LV2_Atom.
+    ## The body of an atom:Object. May be cast to Atom.
     AtomObjectBody* {.bycopy.} = object
         id*: uint32  ## URID, or 0 for blank.
         otype*: uint32  ## URID (same as rdf:type, for fast dispatch).
         ## Contents (a series of property bodies) follow here.
 
-    ## An atom:Object.  May be cast to LV2_Atom.
+    ## An atom:Object.  May be cast to Atom.
     AtomObject* {.bycopy.} = object
         atom*: Atom  ## Atom header.
         body*: AtomObjectBody  ## Body.
 
-    ## The header of an atom:Event.  Note this is NOT an LV2_Atom.
+    ## The header of an atom:Event.  Note this is NOT an Atom.
     AtomEventTime* {.bycopy, union.} = object
         frames*: int64  ## Time in audio frames.
         beats*: cdouble  ## Time in beats.
@@ -175,13 +160,13 @@ type
         ## Body atom contents follow here.
 
     ##
-    ## The body of an atom:Sequence (a sequence of events).
+    ## The body of an AtomSequence (a sequence of events).
     ##
-    ## The unit field is either a URID that described an appropriate time stamp
+    ## The unit field is either a Urid that described an appropriate time stamp
     ## type, or may be 0 where a default stamp is known.  For
-    ## LV2_Descriptor::run(), the default stamp is audio frames.
+    ## lv2Descriptor.run(), the default stamp is audio frames.
     ##
-    ## The contents of a sequence is a series of LV2_Atom_Event, each aligned
+    ## The contents of a sequence is a series of AtomEvent, each aligned
     ## to 64-bits, for example:
     ## <pre>
     ## | Event 1 (size 6)                              | Event 2
diff --git a/src/nymph/atom/util.nim b/src/nymph/atom/util.nim
index 7193666..6df4228 100644
--- a/src/nymph/atom/util.nim
+++ b/src/nymph/atom/util.nim
@@ -12,14 +12,7 @@
 
 from system/ansi_c import c_memcmp, c_memcpy
 import ../atom
-
-
-##
-## Increment pointer `p` by `offset` that jumps memory in increments of
-## the size of `T`.
-##
-proc `+`*[T](p: ptr T, offset: SomeInteger): ptr T =
-    return cast[ptr T](cast[int](p) +% (offset.int * sizeof(T)))
+import ../ptrmath
 
 ##
 ## Pad a size to 64 bits.
@@ -73,7 +66,7 @@ proc atomSequenceIsEnd*(body: ptr AtomSequenceBody; size: Natural; i: ptr AtomEv
 ## Return an iterator to the element following `i`.
 ##
 proc atomSequenceNext*(i: ptr AtomEvent): ptr AtomEvent {.inline.} =
-    return cast[ptr AtomEvent](i + sizeof(AtomEvent) + atomPadSize(i.body.size))
+    return cast[ptr AtomEvent](cast[ptr uint8](i) + sizeof(AtomEvent) + atomPadSize(i.body.size))
 
 ##
 ## An iterator for looping over all events in a Sequence.
diff --git a/src/nymph/ptrmath.nim b/src/nymph/ptrmath.nim
new file mode 100644
index 0000000..9ee7395
--- /dev/null
+++ b/src/nymph/ptrmath.nim
@@ -0,0 +1,6 @@
+##
+## Increment pointer `p` by `offset` that jumps memory in increments of
+## the size of `T`.
+##
+proc `+`*[T](p: ptr T, offset: SomeInteger): ptr T =
+    return cast[ptr T](cast[int](p) +% (offset.int * sizeof(T)))
diff --git a/src/nymph/urid.nim b/src/nymph/urid.nim
index 06c0d8c..e6e1c63 100644
--- a/src/nymph/urid.nim
+++ b/src/nymph/urid.nim
@@ -15,27 +15,23 @@ const
     lv2UridUnmap* = lv2UridPrefix & "unmap"
 
 ##
-## Opaque pointer to host data for uridMap.
+## Opaque pointer to host data for UridMap.
 ##
-
 type UridMapHandle* = pointer
 
 ##
 ## Opaque pointer to host data for uridUnmap.
 ##
-
 type UridUnmapHandle* = pointer
 
 ##
 ## URI mapped to an integer.
 ##
-
 type Urid* = distinct uint32
 
 ##
-## URID Map Feature (LV2_URID__map)
+## URID Map Feature (lv2UridMap)
 ##
-
 type UridMap* {.bycopy.} = object
     ##
     ## Opaque pointer to host data.
@@ -67,11 +63,9 @@ type UridMap* {.bycopy.} = object
     ##
     map*: proc (handle: UridMapHandle; uri: cstring): Urid
 
-
 ##
-## URI Unmap Feature (LV2_URID__unmap)
+## URI Unmap Feature (lv2UridUnmap)
 ##
-
 type UridUnmap* {.bycopy.} = object
     ##
     ## Opaque pointer to host data.
@@ -97,4 +91,4 @@ type UridUnmap* {.bycopy.} = object
     ##
     unmap*: proc (handle: UridUnmapHandle; urid: Urid): cstring
 
-proc `==`* (x: Urid, y: Urid): bool {.borrow.}
\ No newline at end of file
+proc `==`* (x: Urid, y: Urid): bool {.borrow.}
diff --git a/src/nymph/util.nim b/src/nymph/util.nim
index 38833ef..74d65b2 100644
--- a/src/nymph/util.nim
+++ b/src/nymph/util.nim
@@ -1,4 +1,4 @@
-import ../nymph
+import core
 
 ## Return the data for a feature in a features array.