PcmBuffer: move code to new class ReusableBuffer

ReusableBuffer is more generic.

src/pcm/PcmBuffer.cxx

@@ -21,16 +21,6 @@
 #include "PcmBuffer.hxx"
 #include "poison.h"
 
-/**
- * Align the specified size to the next 8k boundary.
- */
-constexpr
-static size_t
-align_8k(size_t size)
-{
-	return ((size - 1) | 0x1fff) + 1;
-}
-
 void *
 PcmBuffer::Get(size_t new_size)
 {
@@ -39,18 +29,5 @@ PcmBuffer::Get(size_t new_size)
 		   be an error condition */
 		new_size = 1;
 
-	if (size < new_size) {
-		/* free the old buffer */
-		g_free(buffer);
-
-		size = align_8k(new_size);
-		buffer = g_malloc(size);
-	} else {
-		/* discard old buffer contents */
-		poison_undefined(buffer, size);
-	}
-
-	assert(size >= new_size);
-
-	return buffer;
+	return buffer.Get(new_size);
 }

src/pcm/PcmBuffer.hxx

@@ -20,33 +20,22 @@
 #ifndef PCM_BUFFER_HXX
 #define PCM_BUFFER_HXX
 
-#include "check.h"
+#include "util/ReusableArray.hxx"
 #include "gcc.h"
 
-#include <glib.h>
-
-#include <assert.h>
+#include <stdint.h>
 
 /**
  * Manager for a temporary buffer which grows as needed.  We could
  * allocate a new buffer every time pcm_convert() is called, but that
  * would put too much stress on the allocator.
  */
-struct PcmBuffer {
-	void *buffer;
-
-	size_t size;
-
-	PcmBuffer():buffer(nullptr), size(0) {}
-
-	~PcmBuffer() {
-		g_free(buffer);
-	}
+class PcmBuffer {
+	ReusableArray<uint8_t, 8192> buffer;
 
+public:
 	void Clear() {
-		g_free(buffer);
-		buffer = nullptr;
-		size = 0;
+		buffer.Clear();
 	}
 
 	/**

src/pcm/PcmChannels.hxx

@@ -23,7 +23,7 @@
 #include <stdint.h>
 #include <stddef.h>
 
-struct PcmBuffer;
+class PcmBuffer;
 
 /**
  * Changes the number of channels in 16 bit PCM data.

src/pcm/PcmDsdUsb.hxx

@@ -25,7 +25,7 @@
 #include <stdint.h>
 #include <stddef.h>
 
-struct PcmBuffer;
+class PcmBuffer;
 
 /**
  * Pack DSD 1 bit samples into (padded) 24 bit PCM samples for

src/pcm/PcmFormat.hxx

@@ -25,7 +25,7 @@
 #include <stdint.h>
 #include <stddef.h>
 
-struct PcmBuffer;
+class PcmBuffer;
 class PcmDither;
 
 /**