Update RageSoundMixBuffer

1) Set a buffer of 2MB instead of setting the buffer to nullptr and depend on it being grown by assets being loaded at the game launch

2) Update some C style code to C++ style

3) Improve Extend feature to support handling a larger number of samples, and error handling in case of a memory allocation failure

src/RageSoundMixBuffer.cpp

@@ -4,17 +4,28 @@
 
 #include <cmath>
 #include <cstdint>
+#include <cstdlib>
 
 RageSoundMixBuffer::RageSoundMixBuffer()
 {
-	m_iBufSize = m_iBufUsed = 0;
+	// See how many samples we can stuff into 2MB.
-	m_pMixbuf = nullptr;
+	size_t BUF_SIZE = 2 * 1024 * 1024 / sizeof(float);
+	
+	m_pMixbuf = static_cast<float*>(std::malloc(BUF_SIZE * sizeof(float)));
+	if (m_pMixbuf == nullptr) {
+		ASSERT_M(false, "Failed to allocate memory for the sound mixing buffer");
+	}
+	
+	m_iBufSize = BUF_SIZE;
+	std::memset(m_pMixbuf, 0, m_iBufSize * sizeof(float));
+	m_iBufUsed = 0;
 	m_iOffset = 0;
 }
 
+
 RageSoundMixBuffer::~RageSoundMixBuffer()
 {
-	free( m_pMixbuf );
+	std::free(m_pMixbuf);
 }
 
 /* write() will start mixing iOffset samples into the buffer.  Be careful; this is
@@ -26,16 +37,20 @@ void RageSoundMixBuffer::SetWriteOffset( int iOffset )
 
 void RageSoundMixBuffer::Extend(unsigned iSamples)
 {
-	const unsigned realsize = iSamples+m_iOffset;
+	const std::uint64_t realsize = static_cast<std::uint64_t>(iSamples) + static_cast<std::uint64_t>(m_iOffset);
 	if( m_iBufSize < realsize )
 	{
-		m_pMixbuf = (float *) realloc( m_pMixbuf, sizeof(float) * realsize );
+		m_pMixbuf = static_cast<float*>(std::realloc(m_pMixbuf, sizeof(float) * realsize));
+		if (m_pMixbuf == nullptr)
+		{
+			ASSERT_M(false, "Failed to re-allocate memory for the sound mixing buffer.");
+		}
 		m_iBufSize = realsize;
 	}
 
 	if( m_iBufUsed < realsize )
 	{
-		memset( m_pMixbuf + m_iBufUsed, 0, (realsize - m_iBufUsed) * sizeof(float) );
+		std::memset(m_pMixbuf + m_iBufUsed, 0, (realsize - m_iBufUsed) * sizeof(float));
 		m_iBufUsed = realsize;
 	}
 }
@@ -73,7 +88,7 @@ void RageSoundMixBuffer::read( std::int16_t *pBuf )
 
 void RageSoundMixBuffer::read( float *pBuf )
 {
-	memcpy( pBuf, m_pMixbuf, m_iBufUsed*sizeof(float) );
+	std::memcpy( pBuf, m_pMixbuf, m_iBufUsed * sizeof(float) );
 	m_iBufUsed = 0;
 }
 

src/RageSoundMixBuffer.h

@@ -11,10 +11,10 @@ public:
 	RageSoundMixBuffer();
 	~RageSoundMixBuffer();
 
-	/* Mix the given buffer of samples. */
+	// Mix the given buffer of samples.
 	void write( const float *pBuf, unsigned iSize, int iSourceStride = 1, int iDestStride = 1 );
 
-	/* Extend the buffer as if write() was called with a buffer of silence. */
+	// Extend the buffer as if write() was called with a buffer of silence.
 	void Extend( unsigned iSamples );
 
 	void read( std::int16_t *pBuf );
@@ -26,8 +26,8 @@ public:
 
 private:
 	float *m_pMixbuf;
-	unsigned m_iBufSize; /* actual allocated samples */
+	std::uint64_t m_iBufSize; // actual allocated samples
-	unsigned m_iBufUsed; /* used samples */
+	std::uint64_t m_iBufUsed; // used samples
 	int m_iOffset;
 };