Better detection of Big-Endian and PowerPC CPU

LZ4Demo : correction : produces compatible streams on both big-endian and little-endian systems

git-svn-id: https://lz4.googlecode.com/svn/trunk@52 650e7d94-2a16-8b24-b05c-7c0b3f6821cd

1 files changed, 43 insertions, 27 deletions

diff --git a/lz4.c b/lz4.c
index 8591110..4bc306c 100644
--- a/lz4.c
+++ b/lz4.c
@@ -28,16 +28,30 @@
 */

 

 //**************************************

-// Compilation Directives

+// Tuning parameters

 //**************************************

-#if __STDC_VERSION__ >= 199901L

+// Increasing this value improves compression ratio

+// Lowering this value reduces memory usage

+// Reduced memory usage typically improves speed, due to cache effect (ex : L1 32KB for Intel, L1 64KB for AMD)

+// Memory usage formula : N->2^(N+2) Bytes (examples : 12 -> 16KB ; 17 -> 512KB)

+#define COMPRESSIONLEVEL 12

+

+// Uncomment this parameter if your target system does not support hardware bit count

+//#define _FORCE_SW_BITCOUNT

+

+

+

+//**************************************

+// Compiler Options

+//**************************************

+#if __STDC_VERSION__ >= 199901L    // C99

   /* "restrict" is a known keyword */

 #else

 #define restrict  // Disable restrict

 #endif

 

 #ifdef _MSC_VER

-#define inline __forceinline

+#define inline __forceinline    // Visual is not C99, but supports inline

 #endif

 

 #ifdef __GNUC__

@@ -46,10 +60,10 @@
 #define _PACKED

 #endif

 

-#if (__x86_64__ || __ppc64__ || _WIN64 || __LP64__)   // Detect 64 bits mode

-#define ARCH64 1

+#ifdef _MSC_VER  // Visual Studio

+#define bswap16(i) _byteswap_ushort(i)

 #else

-#define ARCH64 0

+#define bswap16(i) (((i)>>8) | ((i)<<8))

 #endif

 

 

@@ -62,18 +76,6 @@
 

 

 //**************************************

-// Performance parameter               

-//**************************************

-// Increasing this value improves compression ratio

-// Lowering this value reduces memory usage

-// Lowering may also improve speed, typically on reaching cache size limits (L1 32KB for Intel, 64KB for AMD)

-// Memory usage formula for 32 bits systems : N->2^(N+2) Bytes (examples : 17 -> 512KB ; 12 -> 16KB)

-#define HASH_LOG 12

-

-//#define _FORCE_SW_BITCOUNT   // Uncomment for better performance if target platform has no hardware support for LowBitCount

-

-

-//**************************************

 // Basic Types

 //**************************************

 #if defined(_MSC_VER)    // Visual Studio does not support 'stdint' natively

@@ -107,6 +109,7 @@
 #define MAXD_LOG 16

 #define MAX_DISTANCE ((1 << MAXD_LOG) - 1)

 

+#define HASH_LOG COMPRESSIONLEVEL

 #define HASHTABLESIZE (1 << HASH_LOG)

 #define HASH_MASK (HASHTABLESIZE - 1)

 

@@ -147,6 +150,19 @@ typedef struct _U16_S
 //**************************************

 // Architecture-specific macros

 //**************************************

+#if (__x86_64__ || __x86_64 || __amd64__ || __amd64 || __ppc64__ || _WIN64 || __LP64__ || _LP64)   // Detects 64 bits mode

+#define ARCH64 1

+#else

+#define ARCH64 0

+#endif

+

+// The following macro auto-detects Big-endian CPU. You can manually override it in case of bad detection.

+#if (__BIG_ENDIAN__ || _BIG_ENDIAN || _ARCH_PPC || __PPC__ || __PPC || PPC || __powerpc__ || __powerpc || powerpc || ((defined(__BYTE_ORDER__)&&(__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))) )

+#define CPU_BIG_ENDIAN 1

+#else

+// Little Endian assumed. PDP Endian and other very rare endian format are unsupported.

+#endif

+

 #if ARCH64	// 64-bit

 #define STEPSIZE 8

 #define UARCH U64

@@ -167,14 +183,14 @@ typedef struct _U16_S
 #define INITBASE(base)			const int base = 0

 #endif

 

-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__

+#if CPU_BIG_ENDIAN

+#define LZ4_READ_LITTLEENDIAN_16(d,s,p) { U16 v = A16(p); v = bswap16(v); d = (s) - v; }

+#define LZ4_WRITE_LITTLEENDIAN_16(p,i) { U16 v = (U16)(i); v = bswap16(v); A16(p) = v; p+=2; }

+#define LZ4_NbCommonBytes LZ4_NbCommonBytes_BigEndian

+#else		// Little Endian

 #define LZ4_READ_LITTLEENDIAN_16(d,s,p) { d = (s) - A16(p); }

 #define LZ4_WRITE_LITTLEENDIAN_16(p,v) { A16(p) = v; p+=2; }

 #define LZ4_NbCommonBytes LZ4_NbCommonBytes_LittleEndian

-#else		// Big Endian

-#define LZ4_READ_LITTLEENDIAN_16(d,s,p) { int delta = p[0]; delta += p[1] << 8; d = (s) - delta; }

-#define LZ4_WRITE_LITTLEENDIAN_16(p,v) { int delta = v; *p++ = delta; *p++ = delta>>8; }

-#define LZ4_NbCommonBytes LZ4_NbCommonBytes_BigEndian

 #endif

 

 

@@ -616,7 +632,7 @@ int LZ4_uncompress(char* source,
 		if (op-ref<STEPSIZE)

 		{

 #if ARCH64

-			size_t dec2table[]={0, 4, 4, 3, 4, 5, 6, 7};

+			size_t dec2table[]={0, 0, 0, -1, 0, 1, 2, 3};

 			size_t dec2 = dec2table[op-ref];

 #else

 			const int dec2 = 0;

@@ -626,7 +642,7 @@ int LZ4_uncompress(char* source,
 			*op++ = *ref++;

 			*op++ = *ref++;

 			ref -= dec[op-ref];

-			A32(op)=A32(ref); op += STEPSIZE-4; ref += STEPSIZE-4;

+			A32(op)=A32(ref); op += STEPSIZE-4;

 			ref -= dec2;

 		} else { LZ4_COPYSTEP(ref,op); }

 		cpy = op + length - (STEPSIZE-4);

@@ -703,7 +719,7 @@ int LZ4_uncompress_unknownOutputSize(
 		if (op-ref<STEPSIZE)

 		{

 #if ARCH64

-			size_t dec2table[]={0, 4, 4, 3, 4, 5, 6, 7};

+			size_t dec2table[]={0, 0, 0, -1, 0, 1, 2, 3};

 			size_t dec2 = dec2table[op-ref];

 #else

 			const int dec2 = 0;

@@ -713,7 +729,7 @@ int LZ4_uncompress_unknownOutputSize(
 			*op++ = *ref++;

 			*op++ = *ref++;

 			ref -= dec[op-ref];

-			A32(op)=A32(ref); op += STEPSIZE-4; ref += STEPSIZE-4;

+			A32(op)=A32(ref); op += STEPSIZE-4;

 			ref -= dec2;

 		} else { LZ4_COPYSTEP(ref,op); }

 		cpy = op + length - (STEPSIZE-4);