There we go, a dedicated byte swapping class for endian adjustment.

I even throw in a piece of premature optimization.


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@3589 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/media/media-add-ons/mixer/ByteSwap.cpp

@@ -0,0 +1,132 @@
+/* Copyright (C) 2003 Marcus Overhagen
+ * Released under terms of the MIT license.
+ *
+ * A simple byte order swapping class for the audio mixer.
+ */
+
+#include <MediaDefs.h>
+#include <ByteOrder.h>
+#include "ByteSwap.h"
+#include "debug.h"
+
+static void swap_float(void *buffer, size_t bytecount);
+static void swap_int32(void *buffer, size_t bytecount);
+static void swap_int16(void *buffer, size_t bytecount);
+static void do_nothing(void *buffer, size_t bytecount);
+
+ByteSwap::ByteSwap(uint32 format)
+{
+	switch (format) {
+		case media_raw_audio_format::B_AUDIO_FLOAT:
+			fFunc = &swap_float;
+			break;
+		case media_raw_audio_format::B_AUDIO_INT:
+			fFunc = &swap_int32;
+			break;
+		case media_raw_audio_format::B_AUDIO_SHORT:
+			fFunc = &swap_int16;
+			break;
+		default:
+			fFunc = &do_nothing;
+			break;
+	}
+}
+
+ByteSwap::~ByteSwap()
+{
+}
+
+void
+do_nothing(void *buffer, size_t bytecount)
+{
+}
+
+#ifdef __INTEL__
+
+// optimized for IA32 platform
+
+void
+swap_float(void *buffer, size_t bytecount)
+{
+	swap_data(B_FLOAT_TYPE, buffer, bytecount, B_SWAP_ALWAYS); // XXX should be optimized
+}
+
+void
+swap_int32(void *buffer, size_t bytecount)
+{
+	swap_data(B_INT32_TYPE, buffer, bytecount, B_SWAP_ALWAYS); // XXX should be optimized
+}
+
+void
+swap_int16(void *buffer, size_t bytecount)
+{
+	// GCC FAQ: To write an asm which modifies an input operand but does
+	//          not output anything usable, specify that operand as an
+	//          output operand outputting to an unused dummy variable.
+	uint32 dummy1;
+	uint32 dummy2;
+	asm (
+	"pushl	%%ebx	\n\t"
+	"movl	%%eax, %%ebx	\n\t"
+	"movl	%%edx, %%eax	\n\t"
+	"andl   $0xFFFFFFE0,%%eax	\n\t"
+	"pushl	%%eax	\n\t"
+	"swap_int16_swap: \n\t"
+		"rolw	$8,-32(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-30(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-28(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-26(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-24(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-22(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-20(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-18(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-16(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-14(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-12(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-10(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-8(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-6(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-4(%%ebx,%%eax)	\n\t"
+		"rolw	$8,-2(%%ebx,%%eax)	\n\t"
+		"subl	$32,%%eax	\n\t"
+		"jnz	swap_int16_swap	\n\t"
+	"popl	%%eax	\n\t"
+	"addl	%%eax,%%ebx	\n\t"
+	"andl	$0x1F,%%edx	\n\t"
+	"jz		swap_int16_end	\n\t"
+	"addl	%%ebx, %%edx	\n\t"
+	"swap_int16_swap2: \n\t"
+		"rolw	$8,(%%ebx)	\n\t"
+		"addl	$2,%%ebx	\n\t"
+		"cmpl	%%edx,%%ebx	\n\t"
+		"jne	swap_int16_swap2 \n\t"
+	"swap_int16_end:	\n\t"
+	"popl	%%ebx \n\t"
+	: "=a" (dummy1), "=d" (dummy2)
+	: "d" (bytecount), "a" (buffer)
+	: "cc", "memory");
+}
+
+#else
+
+// non optimized default versions, do not remove
+
+void
+swap_float(void *buffer, size_t bytecount)
+{
+	swap_data(B_FLOAT_TYPE, buffer, bytecount, B_SWAP_ALWAYS);
+}
+
+void
+swap_int32(void *buffer, size_t bytecount)
+{
+	swap_data(B_INT32_TYPE, buffer, bytecount, B_SWAP_ALWAYS);
+}
+
+void
+swap_int16(void *buffer, size_t bytecount)
+{
+	swap_data(B_INT16_TYPE, buffer, bytecount, B_SWAP_ALWAYS);
+}
+
+#endif

src/add-ons/media/media-add-ons/mixer/ByteSwap.h

@@ -0,0 +1,28 @@
+#ifndef _BYTE_SWAP_H
+#define _BYTE_SWAP_H
+
+/* Copyright (C) 2003 Marcus Overhagen
+ * Released under terms of the MIT license.
+ *
+ * A simple byte order swapping class for the audio mixer.
+ */
+
+class ByteSwap
+{
+public:
+	ByteSwap(uint32 format);
+	~ByteSwap();
+	
+	void Swap(void *buffer, size_t bytecount);
+
+private:
+	void (*fFunc)(void *, size_t);
+};
+
+inline void
+ByteSwap::Swap(void *buffer, size_t bytecount)
+{
+	(*fFunc)(buffer, bytecount);
+}
+
+#endif

src/add-ons/media/media-add-ons/mixer/Jamfile

@@ -4,6 +4,7 @@ UsePrivateHeaders media ;
 
 Addon mixer.media_addon : media :
 	AudioMixer.cpp
+	ByteSwap.cpp
 	MixerAddOn.cpp
 	MixerCore.cpp
 	MixerInput.cpp