pcm/Dsd2Pcm: convert to class

src/pcm/Dsd2Pcm.cxx

@@ -43,13 +43,7 @@ static constexpr size_t HTAPS = 48;
 /** number of "8 MACs" lookup tables */
 static constexpr int CTABLES = (HTAPS + 7) / 8;
 
-/* must be a power of two */
-static constexpr int FIFOSIZE = 16;
-
-/** bit mask for FIFO offsets */
-static constexpr size_t FIFOMASK = FIFOSIZE - 1;
-
-static_assert(FIFOSIZE*8 >= HTAPS*2, "FIFOSIZE too small");
+static_assert(Dsd2Pcm::FIFOSIZE * 8 >= HTAPS * 2, "FIFOSIZE too small");
 
 /*
  * Properties of this 96-tap lowpass filter when applied on a signal
@@ -154,34 +148,13 @@ GenerateCtable(int t) noexcept
 
 static constexpr auto ctables = GenerateArray<CTABLES>(GenerateCtable);
 
-struct dsd2pcm_ctx_s
-{
-	unsigned char fifo[FIFOSIZE];
-	unsigned fifopos;
-};
-
-dsd2pcm_ctx *
-dsd2pcm_init() noexcept
-{
-	dsd2pcm_ctx* ptr;
-	ptr = (dsd2pcm_ctx*) malloc(sizeof(dsd2pcm_ctx));
-	if (ptr) dsd2pcm_reset(ptr);
-	return ptr;
-}
-
-void
-dsd2pcm_destroy(dsd2pcm_ctx *ptr) noexcept
-{
-	free(ptr);
-}
-
 void
-dsd2pcm_reset(dsd2pcm_ctx *ptr) noexcept
+Dsd2Pcm::Reset() noexcept
 {
 	int i;
 	for (i=0; i<FIFOSIZE; ++i)
-		ptr->fifo[i] = 0x69; /* my favorite silence pattern */
-	ptr->fifopos = 0;
+		fifo[i] = 0x69; /* my favorite silence pattern */
+	fifopos = 0;
 	/* 0x69 = 01101001
 	 * This pattern "on repeat" makes a low energy 352.8 kHz tone
 	 * and a high energy 1.0584 MHz tone which should be filtered
@@ -190,32 +163,31 @@ dsd2pcm_reset(dsd2pcm_ctx *ptr) noexcept
 }
 
 void
-dsd2pcm_translate(dsd2pcm_ctx *ptr,
-		  size_t samples,
-		  const unsigned char *src, ptrdiff_t src_stride,
-		  bool lsbf,
-		  float *dst, ptrdiff_t dst_stride) noexcept
+Dsd2Pcm::Translate(size_t samples,
+		   const unsigned char *src, ptrdiff_t src_stride,
+		   bool lsbf,
+		   float *dst, ptrdiff_t dst_stride) noexcept
 {
 	unsigned ffp;
 	unsigned i;
 	unsigned bite1, bite2;
 	unsigned char* p;
 	double acc;
-	ffp = ptr->fifopos;
+	ffp = fifopos;
 	while (samples-- > 0) {
 		bite1 = *src & 0xFFu;
 		if (lsbf) bite1 = bit_reverse(bite1);
-		ptr->fifo[ffp] = bite1; src += src_stride;
-		p = ptr->fifo + ((ffp-CTABLES) & FIFOMASK);
+		fifo[ffp] = bite1; src += src_stride;
+		p = fifo + ((ffp-CTABLES) & FIFOMASK);
 		*p = bit_reverse(*p);
 		acc = 0;
 		for (i=0; i<CTABLES; ++i) {
-			bite1 = ptr->fifo[(ffp              -i) & FIFOMASK] & 0xFF;
-			bite2 = ptr->fifo[(ffp-(CTABLES*2-1)+i) & FIFOMASK] & 0xFF;
+			bite1 = fifo[(ffp              -i) & FIFOMASK] & 0xFF;
+			bite2 = fifo[(ffp-(CTABLES*2-1)+i) & FIFOMASK] & 0xFF;
 			acc += ctables[i][bite1] + ctables[i][bite2];
 		}
 		*dst = (float)acc; dst += dst_stride;
 		ffp = (ffp + 1) & FIFOMASK;
 	}
-	ptr->fifopos = ffp;
+	fifopos = ffp;
 }

src/pcm/Dsd2Pcm.hxx

@@ -33,58 +33,47 @@ or implied, of Sebastian Gesemann.
 
 #include <stddef.h>
 
-struct dsd2pcm_ctx_s;
-
-typedef struct dsd2pcm_ctx_s dsd2pcm_ctx;
-
-/**
- * initializes a "dsd2pcm engine" for one channel
- * (precomputes tables and allocates memory)
- *
- * This is the only function that is not thread-safe in terms of the
- * POSIX thread-safety definition because it modifies global state
- * (lookup tables are computed during the first call)
- */
-dsd2pcm_ctx *
-dsd2pcm_init() noexcept;
-
-/**
- * deinitializes a "dsd2pcm engine"
- * (releases memory, don't forget!)
- */
-void
-dsd2pcm_destroy(dsd2pcm_ctx *ctx) noexcept;
-
-/**
- * clones the context and returns a pointer to the
- * newly allocated copy
- */
-dsd2pcm_ctx *
-dsd2pcm_clone(dsd2pcm_ctx *ctx) noexcept;
-
-/**
- * resets the internal state for a fresh new stream
- */
-void
-dsd2pcm_reset(dsd2pcm_ctx *ctx) noexcept;
-
 /**
- * "translates" a stream of octets to a stream of floats
- * (8:1 decimation)
- * @param ctx -- pointer to abstract context (buffers)
- * @param samples -- number of octets/samples to "translate"
- * @param src -- pointer to first octet (input)
- * @param src_stride -- src pointer increment
- * @param lsbitfirst -- bitorder, 0=msb first, 1=lsbfirst
- * @param dst -- pointer to first float (output)
- * @param dst_stride -- dst pointer increment
+ * A "dsd2pcm engine" for one channel.
  */
-void
-dsd2pcm_translate(dsd2pcm_ctx *ctx,
-		  size_t samples,
-		  const unsigned char *src, ptrdiff_t src_stride,
-		  bool lsbitfirst,
-		  float *dst, ptrdiff_t dst_stride) noexcept;
+class Dsd2Pcm {
+public:
+	/* must be a power of two */
+	static constexpr int FIFOSIZE = 16;
+
+private:
+	/** bit mask for FIFO offsets */
+	static constexpr size_t FIFOMASK = FIFOSIZE - 1;
+
+	unsigned char fifo[FIFOSIZE];
+	unsigned fifopos;
+
+public:
+	Dsd2Pcm() noexcept {
+		Reset();
+	}
+
+	/**
+	 * resets the internal state for a fresh new stream
+	 */
+	void Reset() noexcept;
+
+	/**
+	 * "translates" a stream of octets to a stream of floats
+	 * (8:1 decimation)
+	 * @param ctx -- pointer to abstract context (buffers)
+	 * @param samples -- number of octets/samples to "translate"
+	 * @param src -- pointer to first octet (input)
+	 * @param src_stride -- src pointer increment
+	 * @param lsbitfirst -- bitorder, 0=msb first, 1=lsbfirst
+	 * @param dst -- pointer to first float (output)
+	 * @param dst_stride -- dst pointer increment
+	 */
+	void Translate(size_t samples,
+		       const unsigned char *src, ptrdiff_t src_stride,
+		       bool lsbitfirst,
+		       float *dst, ptrdiff_t dst_stride) noexcept;
+};
 
 #endif /* include guard DSD2PCM_H_INCLUDED */
 

src/pcm/PcmDsd.cxx

@@ -31,8 +31,7 @@ PcmDsd::PcmDsd() noexcept
 PcmDsd::~PcmDsd() noexcept
 {
 	for (auto i : dsd2pcm)
-		if (i != nullptr)
-			dsd2pcm_destroy(i);
+		delete i;
 }
 
 void
@@ -40,7 +39,7 @@ PcmDsd::Reset() noexcept
 {
 	for (auto i : dsd2pcm)
 		if (i != nullptr)
-			dsd2pcm_reset(i);
+			i->Reset();
 }
 
 ConstBuffer<float>
@@ -57,15 +56,12 @@ PcmDsd::ToFloat(unsigned channels, ConstBuffer<uint8_t> src) noexcept
 	float *dest = buffer.GetT<float>(num_samples);
 
 	for (unsigned c = 0; c < channels; ++c) {
-		if (dsd2pcm[c] == nullptr) {
-			dsd2pcm[c] = dsd2pcm_init();
-			if (dsd2pcm[c] == nullptr)
-				return nullptr;
-		}
+		if (dsd2pcm[c] == nullptr)
+			dsd2pcm[c] = new Dsd2Pcm();
 
-		dsd2pcm_translate(dsd2pcm[c], num_frames,
-				  src.data + c, channels,
-				  false, dest + c, channels);
+		dsd2pcm[c]->Translate(num_frames,
+				      src.data + c, channels,
+				      false, dest + c, channels);
 	}
 
 	return { dest, num_samples };

src/pcm/PcmDsd.hxx

@@ -28,6 +28,7 @@
 #include <stdint.h>
 
 template<typename T> struct ConstBuffer;
+class Dsd2Pcm;
 
 /**
  * Wrapper for the dsd2pcm library.
@@ -35,7 +36,7 @@ template<typename T> struct ConstBuffer;
 class PcmDsd {
 	PcmBuffer buffer;
 
-	std::array<struct dsd2pcm_ctx_s *, MAX_CHANNELS> dsd2pcm;
+	std::array<Dsd2Pcm *, MAX_CHANNELS> dsd2pcm;
 
 public:
 	PcmDsd() noexcept;