add port setup code

src/image.zig

@@ -1,4 +1,6 @@
 const std = @import("std");
+const lv2 = @import("lv2_helpers.zig");
+
 const c = @cImport({
     @cInclude("sndfile.h");
 
@@ -101,8 +103,13 @@ pub const Image = struct {
         pos: plugins.Position,
         params: plugins.ParamList,
     ) !void {
-        const context = try plugins.makeContext(self.allocator, plugin_uri);
+        var context = try plugins.makeContext(self.allocator, plugin_uri);
         std.debug.warn("world: {}\n", context.world);
         std.debug.warn("plugin: {}\n", context.plugin);
+
+        var ports = try lv2.setupPorts(&context);
+        for (ports) |port| {
+            std.debug.warn("port: {}\n", port.*);
+        }
     }
 };

src/lv2_helpers.zig

@@ -1,4 +1,7 @@
-const c = @cImport({
+const std = @import("std");
+const plugin = @import("plugin.zig");
+
+pub const c = @cImport({
     @cInclude("lilv/lilv.h");
     @cInclude("lv2/core/lv2.h");
 });
@@ -37,3 +40,111 @@ pub fn lilv_instance_deactivate(instance: [*c]c.LilvInstance) void {
         instance.?.*.lv2_descriptor.?.*.deactivate.?(instance.?.*.lv2_handle);
     }
 }
+
+pub const PortType = enum {
+    Control,
+    Audio,
+};
+
+pub const Port = struct {
+    lilv_port: ?*const c.LilvPort,
+    ptype: PortType,
+    index: u32,
+    value: f32,
+    is_input: bool,
+    optional: bool,
+};
+
+/// Setup ports for a given plugin. Gives an array to pointers of Port structs.
+/// This setup is required so we link the plugin to the ports later on, and
+/// also link our buffers, and control values.
+pub fn setupPorts(ctx: *plugin.Context) ![]*Port {
+    var world = ctx.world;
+    const n_ports: u32 = c.lilv_plugin_get_num_ports(ctx.plugin);
+
+    var ports = try ctx.allocator.alloc(*Port, n_ports);
+
+    for (ports) |port_ptr, idx| {
+        var port = try ctx.allocator.create(Port);
+        port.* = Port{
+            .lilv_port = null,
+            .ptype = .Control,
+            .index = f32(0),
+            .value = f32(0),
+            .is_input = false,
+            .optional = false,
+        };
+
+        ports[idx] = port;
+    }
+
+    var values: []f32 = try ctx.allocator.alloc(f32, n_ports);
+    defer ctx.allocator.free(values);
+
+    c.lilv_plugin_get_port_ranges_float(ctx.plugin, null, null, values.ptr);
+
+    // bad solution, but it really do be like that
+    const LV2_CORE__InputPort = try Lv2Core("#InputPort");
+    const LV2_CORE__OutputPort = try Lv2Core("#OutputPort");
+    const LV2_CORE__AudioPort = try Lv2Core("#AudioPort");
+    const LV2_CORE__ControlPort = try Lv2Core("#ControlPort");
+    const LV2_CORE__connectionOptional = try Lv2Core("#connectionOptional");
+
+    var lv2_InputPort = c.lilv_new_uri(world, LV2_CORE__InputPort.ptr);
+    defer std.heap.c_allocator.destroy(lv2_InputPort);
+
+    var lv2_OutputPort = c.lilv_new_uri(world, LV2_CORE__OutputPort.ptr);
+    defer std.heap.c_allocator.destroy(lv2_OutputPort);
+
+    var lv2_AudioPort = c.lilv_new_uri(world, LV2_CORE__AudioPort.ptr);
+    defer std.heap.c_allocator.destroy(lv2_AudioPort);
+
+    var lv2_ControlPort = c.lilv_new_uri(world, LV2_CORE__ControlPort.ptr);
+    defer std.heap.c_allocator.destroy(lv2_ControlPort);
+
+    var lv2_connectionOptional = c.lilv_new_uri(world, LV2_CORE__connectionOptional.ptr);
+    defer std.heap.c_allocator.destroy(lv2_connectionOptional);
+
+    var i: u32 = 0;
+    while (i < n_ports) : (i += 1) {
+        var port: *Port = ports[i];
+
+        const lport = c.lilv_plugin_get_port_by_index(ctx.plugin, i).?;
+
+        port.lilv_port = lport;
+        port.index = i;
+
+        if (std.math.isNan(values[i])) {
+            port.value = f32(0);
+        } else {
+            port.value = values[i];
+        }
+
+        port.optional = c.lilv_port_has_property(ctx.plugin, lport, lv2_connectionOptional);
+
+        if (c.lilv_port_is_a(ctx.plugin, lport, lv2_InputPort)) {
+            port.is_input = true;
+        } else if (!c.lilv_port_is_a(ctx.plugin, lport, lv2_OutputPort) and !port.optional) {
+            std.debug.warn("Port {} is neither input or output\n", i);
+            return error.UnassignedIOPort;
+        }
+
+        // check if port is an audio or control port
+        if (c.lilv_port_is_a(ctx.plugin, lport, lv2_ControlPort)) {
+            port.ptype = .Control;
+        } else if (c.lilv_port_is_a(ctx.plugin, lport, lv2_AudioPort)) {
+            port.ptype = .Audio;
+
+            if (port.is_input) {
+                ctx.n_audio_in += 1;
+            } else {
+                ctx.n_audio_out += 1;
+            }
+        } else if (!port.optional) {
+            std.debug.warn("Port {} has unsupported type\n", i);
+            return error.UnsupportedPortType;
+        }
+    }
+
+    return ports;
+}

src/plugin.zig

@@ -1,9 +1,6 @@
 const std = @import("std");
 
-const c = @cImport({
+const c = @import("lv2_helpers.zig").c;
-    @cInclude("lilv/lilv.h");
-    @cInclude("lv2/core/lv2.h");
-});
 
 const ImageError = @import("image.zig").ImageError;
 
@@ -27,8 +24,13 @@ pub const Position = struct {
 
 /// Represents the starting context for a single plugin run.
 pub const Context = struct {
+    allocator: *std.mem.Allocator,
     world: *c.LilvWorld,
-    plugin: *const c.LilvPlugin,
+    plugin: ?*const c.LilvPlugin,
+
+    // they should both be 1.
+    n_audio_in: usize = 0,
+    n_audio_out: usize = 0,
 };
 
 pub fn makeContext(allocator: *std.mem.Allocator, plugin_uri: []const u8) !Context {
@@ -50,5 +52,5 @@ pub fn makeContext(allocator: *std.mem.Allocator, plugin_uri: []const u8) !Conte
 
     c.lilv_node_free(uri);
 
-    return Context{ .world = world, .plugin = plugin };
+    return Context{ .allocator = allocator, .world = world, .plugin = plugin };
 }