split in_buf/out_buf into RunBuffers struct

- add basics of RandomNoise custom plugin

src/custom.zig

@@ -0,0 +1,24 @@
+// Custom plugins
+const std = @import("std");
+const lv2 = @import("lv2_helpers.zig");
+const plugins = @import("plugin.zig");
+
+const c = lv2.c;
+
+const RunContext = plugins.RunContext;
+
+pub const RandomNoise = struct {
+    allocator: *std.mem.Allocator,
+
+    pub fn init(
+        allocator: *std.mem.Allocator,
+    ) RandomNoise {
+        return RandomNoise{
+            .allocator = allocator,
+        };
+    }
+
+    pub fn run(self: *RandomNoise, rctx: *RunContext) void {
+        rctx.in_buf[0] = f32(2);
+    }
+};

src/image.zig

@@ -292,15 +292,18 @@ pub const Image = struct {
         var i: usize = seek_pos.start;
         std.debug.warn("\tseek pos start: {} end: {}\n", seek_pos.start, seek_pos.end);
 
+        var inbuf = rctx.buffers.in;
+        var outbuf = rctx.buffers.out;
+
         while (i <= seek_pos.end) : (i += 1) {
-            const read_bytes = c.sf_readf_float(self.sndfile, rctx.in_buf.ptr, 1);
+            const read_bytes = c.sf_readf_float(self.sndfile, inbuf.ptr, 1);
             if (read_bytes == 0) {
                 std.debug.warn("WARN! reached EOF at idx={}\n", i);
                 break;
             }
 
             lv2.lilv_instance_run(rctx.instance, 1);
-            try swrite(out_file, rctx.out_buf.ptr, 1);
+            try swrite(out_file, outbuf.ptr, 1);
         }
 
         _ = c.sf_seek(self.sndfile, @intCast(i64, seek_pos.end), c.SEEK_SET);
@@ -326,4 +329,12 @@ pub const Image = struct {
         std.debug.warn("saved to '{}'\n", out_path);
         try std.fs.copyFile(self.curpath, out_path);
     }
+
+    pub fn runCustomPlugin(
+        self: *Image,
+        comptime Plugin: type,
+        pos: plugins.Position,
+    ) void {
+        var plugin = Plugin.init(self.allocator);
+    }
 };

src/lang.zig

@@ -26,6 +26,7 @@ pub const CommandType = enum {
     Delay,
     Vinyl,
     RevDelay,
+    Noise,
 };
 
 pub const Command = struct {
@@ -143,6 +144,9 @@ pub const Lang = struct {
         _ = try self.keywords.put("delay", .Delay);
         _ = try self.keywords.put("vinyl", .Vinyl);
         _ = try self.keywords.put("revdelay", .RevDelay);
+
+        // custom implementations (not lv2)
+        _ = try self.keywords.put("noise", .Noise);
     }
 
     pub fn parse(self: *Lang, data: []const u8) !CommandList {

src/plugin.zig

@@ -57,10 +57,36 @@ pub const Context = struct {
     }
 };
 
+/// Specific run context for non-plugins.
+pub const RunBuffers = struct {
+    allocator: *std.mem.Allocator,
+
+    in: []f32,
+    out: []f32,
+
+    pub fn init(allocator: *std.mem.Allocator) !RunBuffers {
+        // we allocate []f32 with size 2 to account for stereo plugins, however
+        // we only use &in_buf[0] and &out_buf[0], and don't use the
+        // (supposedly) right side of neither input or output.
+        var in_buf = try allocator.alloc(f32, 2);
+        std.mem.secureZero(f32, in_buf);
+
+        return RunBuffers{
+            .allocator = allocator,
+            .in = in_buf,
+            .out = try allocator.alloc(f32, 2),
+        };
+    }
+
+    pub fn deinit(self: *RunBuffers) void {
+        self.allocator.free(self.in);
+        self.allocator.free(self.out);
+    }
+};
+
 /// Represents the specific run context of plugin instantation.
 pub const RunContext = struct {
-    in_buf: []f32,
-    out_buf: []f32,
+    buffers: RunBuffers,
     instance: *c.LilvInstance,
 
     pub fn init(
@@ -79,20 +105,23 @@ pub const RunContext = struct {
         std.mem.secureZero(f32, in_buf);
 
         return RunContext{
-            .in_buf = in_buf,
-            .out_buf = try allocator.alloc(f32, 2),
+            .buffers = try RunBuffers.init(allocator),
             .instance = instance.?,
         };
     }
 
     pub fn deinit(self: *RunContext) void {
         c.lilv_instance_free(self.instance);
+        self.buffers.deinit();
     }
 
     pub fn connectPorts(self: *RunContext, ports: []*lv2.Port) void {
         var i: usize = 0;
         var o: usize = 0;
 
+        var in_buf = self.buffers.in;
+        var out_buf = self.buffers.out;
+
         for (ports) |port, p_idx| {
             var p = @intCast(u32, p_idx);
 
@@ -100,10 +129,10 @@ pub const RunContext = struct {
                 .Control => lv2.lilv_instance_connect_port(self.instance, p, &port.value),
                 .Audio => blk: {
                     if (port.is_input) {
-                        lv2.lilv_instance_connect_port(self.instance, p, &self.in_buf[i]);
+                        lv2.lilv_instance_connect_port(self.instance, p, &in_buf[i]);
                         i += 1;
                     } else {
-                        lv2.lilv_instance_connect_port(self.instance, p, &self.out_buf[o]);
+                        lv2.lilv_instance_connect_port(self.instance, p, &out_buf[o]);
                         o += 1;
                     }
                 },

src/runner.zig

@@ -2,6 +2,7 @@ const std = @import("std");
 const lang = @import("lang.zig");
 const images = @import("image.zig");
 const plugin = @import("plugin.zig");
+const custom = @import("custom.zig");
 
 const Position = plugin.Position;
 const ParamList = plugin.ParamList;
@@ -245,6 +246,11 @@ pub const Runner = struct {
         try image.runPlugin("http://plugin.org.uk/swh-plugins/revdelay", pos, params);
     }
 
+    fn noiseCmd(self: *Runner, pos: Position, params: ParamList) !void {
+        var image = try self.getImage();
+        image.runCustomPlugin(custom.RandomNoise, pos);
+    }
+
     fn runCommand(self: *Runner, cmd: *lang.Command) !void {
         var params = ParamList.init(self.allocator);
         defer params.deinit();
@@ -384,6 +390,11 @@ pub const Runner = struct {
                 try self.revDelayCmd(pos, params);
             },
 
+            .Noise => blk: {
+                const pos = try cmd.consumePosition();
+                try self.noiseCmd(pos, params);
+            },
+
             else => blk: {
                 std.debug.warn("Unsupported command: {}\n", cmd.command);
                 break :blk RunError.UnknownCommand;