WAVFileWriter saves WAV files!

firmware/application/capture_thread.hpp

@@ -57,6 +57,91 @@ private:
 	File file;
 };
 
+class WAVFileWriter : public Writer {
+public:
+	WAVFileWriter(
+		const std::string& filename,
+		size_t sampling_rate
+	) : file { filename, File::openmode::out | File::openmode::binary | File::openmode::trunc },
+		header { sampling_rate }
+	{
+		update_header();
+	}
+
+	~WAVFileWriter() {
+		update_header();
+	}
+
+	bool write(const void* const buffer, const size_t bytes) override {
+		const auto success = file.write(buffer, bytes) ;
+		if( success ) {
+			bytes_written += bytes;
+		}
+		return success;
+	}
+
+private:
+	struct fmt_pcm_t {
+		constexpr fmt_pcm_t(
+			const uint32_t sampling_rate
+		) : nSamplesPerSec { sampling_rate },
+			nAvgBytesPerSec { nSamplesPerSec * nBlockAlign }
+		{
+		}
+
+	private:
+		const uint8_t ckID[4] { 'f', 'm', 't', ' ' };
+		const uint32_t cksize { 16 };
+		const uint16_t wFormatTag { 0x0001 };
+		const uint16_t nChannels { 1 };
+		const uint32_t nSamplesPerSec;
+		const uint32_t nAvgBytesPerSec;
+		const uint16_t nBlockAlign { 2 };
+		const uint16_t wBitsPerSample { 16 };
+	};
+
+	struct data_t {
+		void set_size(const uint32_t value) {
+			cksize = value;
+		}
+
+	private:
+		const uint8_t ckID[4] { 'd', 'a', 't', 'a' };
+		uint32_t cksize { 0 };
+	};
+
+	struct header_t {
+		constexpr header_t(
+			const uint32_t sampling_rate
+		) : fmt { sampling_rate }
+		{
+		}
+
+		void set_data_size(const uint32_t value) {
+			data.set_size(value);
+			cksize = sizeof(header_t) + value - 8;
+		}
+
+	private:
+		const uint8_t riff_id[4] { 'R', 'I', 'F', 'F' };
+		uint32_t cksize { 0 };
+		const uint8_t wave_id[4] { 'W', 'A', 'V', 'E' };
+		fmt_pcm_t fmt;
+		data_t data;
+	};
+
+	File file;
+	header_t header;
+	uint64_t bytes_written { 0 };
+
+	void update_header() {
+		header.set_data_size(bytes_written);
+		const auto old_position = file.seek(0);
+		file.write(&header, sizeof(header));
+		file.seek(old_position);
+	}
+};
+
 class StreamOutput {
 public:
 	StreamOutput(