added WAV file writer

README.md

@@ -25,3 +25,11 @@ Implemented are the follwing [Window functions](https://en.wikipedia.org/wiki/Wi
 
 Some constants we need
 
+### [pcm.hh](pcm.hh)
+
+Interface for reading and writing [PCM](https://en.wikipedia.org/wiki/Pulse-code_modulation) data
+
+### [wav.hh](wav.hh)
+
+Read and write [WAV](https://en.wikipedia.org/wiki/WAV) files
+

pcm.hh

@@ -0,0 +1,28 @@
+/*
+Interface for reading and writing PCM data
+
+Copyright 2018 Ahmet Inan <inan@aicodix.de>
+*/
+
+#ifndef PCM_HH
+#define PCM_HH
+
+namespace DSP {
+
+template <typename TYPE>
+struct WritePCM
+{
+	virtual void write(TYPE *, int, int) = 0;
+	virtual void silence(int) = 0;
+};
+
+template <typename TYPE>
+struct ReadPCM
+{
+	virtual void read(TYPE *, int, int) = 0;
+};
+
+}
+
+#endif
+

wav.hh

@@ -0,0 +1,84 @@
+/*
+Read and write WAV files
+
+Copyright 2018 Ahmet Inan <inan@aicodix.de>
+*/
+
+#ifndef WAV_HH
+#define WAV_HH
+
+#include <fstream>
+#include "pcm.hh"
+
+namespace DSP {
+
+template <typename TYPE>
+class WriteWAV : public WritePCM<TYPE>
+{
+	std::ofstream os;
+	int bytes, channels;
+	int offset, factor, min, max;
+	void writeLE(int v, int b)
+	{
+		for (int i = 0; i < b; ++i)
+			os.put(255 & (v >> (8 * i)));
+	}
+public:
+	WriteWAV(const char *name, int rate, int bytes, int channels) : os(name, std::ios::binary | std::ios::trunc), bytes(bytes), channels(channels)
+	{
+		switch (bytes) {
+			case 1:
+				offset = 128;
+				factor = 127;
+				min = 0;
+				max = 255;
+				break;
+			default:
+				bytes = 2;
+				offset = 0;
+				factor = 32767;
+				min = -32768;
+				max = 32767;
+		}
+		os.write("RIFF", 4); // ChunkID
+		writeLE(36, 4); // ChunkSize
+		os.write("WAVE", 4); // Format
+		os.write("fmt ", 4); // Subchunk1ID
+		writeLE(16, 4); // Subchunk1Size
+		writeLE(1, 2); // AudioFormat
+		writeLE(channels, 2); // NumChannels
+		writeLE(rate, 4); // SampleRate
+		writeLE(rate * channels * bytes, 4); // ByteRate
+		writeLE(channels * bytes, 2); // BlockAlign
+		writeLE(8 * bytes, 2); // BitsPerSample
+		os.write("data", 4); // Subchunk2ID
+		writeLE(0, 4); // Subchunk2Size
+	}
+	~WriteWAV()
+	{
+		int size = int(os.tellp()) - 44;
+		os.seekp(4);
+		writeLE(36 + size, 4); // ChunkSize
+		os.seekp(40);
+		writeLE(size, 4); // Subchunk2Size
+	}
+	void write(TYPE *buf, int num, int stride = 1)
+	{
+		for (int n = 0; n < num; ++n) {
+			for (int c = 0; c < channels; ++c) {
+				TYPE v = TYPE(offset) + TYPE(factor) * buf[stride * n + c];
+				writeLE(std::nearbyint(std::clamp(v, TYPE(min), TYPE(max))), bytes);
+			}
+		}
+	}
+	void silence(int num)
+	{
+		for (int i = 0; i < num * channels; ++i)
+			writeLE(offset, bytes);
+	}
+};
+
+}
+
+#endif
+