From 9d58904a66d76f64068fa79858d0f92328caf981 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Thu, 6 Oct 2022 15:17:46 +0300
Subject: [PATCH] Add truncate effect

---
 .../include/psemek/audio/effect/truncate.hpp  | 11 +++++
 libs/audio/source/effect/truncate.cpp         | 47 +++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 libs/audio/include/psemek/audio/effect/truncate.hpp
 create mode 100644 libs/audio/source/effect/truncate.cpp

diff --git a/libs/audio/include/psemek/audio/effect/truncate.hpp b/libs/audio/include/psemek/audio/effect/truncate.hpp
new file mode 100644
index 00000000..71275f31
--- /dev/null
+++ b/libs/audio/include/psemek/audio/effect/truncate.hpp
@@ -0,0 +1,11 @@
+#pragma once
+
+#include <psemek/audio/stream.hpp>
+#include <psemek/audio/duration.hpp>
+
+namespace psemek::audio
+{
+
+	stream_ptr truncate(stream_ptr stream, duration length);
+
+}
diff --git a/libs/audio/source/effect/truncate.cpp b/libs/audio/source/effect/truncate.cpp
new file mode 100644
index 00000000..c9e522b7
--- /dev/null
+++ b/libs/audio/source/effect/truncate.cpp
@@ -0,0 +1,47 @@
+#include <psemek/audio/effect/truncate.hpp>
+
+namespace psemek::audio
+{
+
+	namespace
+	{
+
+		struct truncate_impl
+			: stream
+		{
+			truncate_impl(stream_ptr stream, duration length)
+				: stream_(std::move(stream))
+				, length_(length)
+			{}
+
+			std::optional<std::size_t> length() const override
+			{
+				return length_.samples();
+			}
+
+			std::size_t read(float * data, std::size_t sample_count) override
+			{
+				auto played = stream_->played();
+				auto result = std::min<std::size_t>(length_.samples() - played, sample_count);
+				result = stream_->read(data, result);
+				return result;
+			}
+
+			std::size_t played() const override
+			{
+				return stream_->played();
+			}
+
+		private:
+			stream_ptr stream_;
+			duration length_;
+		};
+
+	}
+
+	stream_ptr truncate(stream_ptr stream, duration length)
+	{
+		return std::make_shared<truncate_impl>(std::move(stream), length);
+	}
+
+}