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Improve isSparse()

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Takayuki MATSUOKA 2015-02-12 19:58:49 +09:00
parent 4a5d92b1d9
commit 01a24afdcf
1 changed files with 46 additions and 0 deletions
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46
programs/lz4io.c
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@ -62,6 +62,27 @@
#include "lz4frame.h"
/**************************************
Basic Types
**************************************/
#if defined(LZ4IO_ENABLE_SPARSE_FILE)
#if defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */
# include <stdint.h>
typedef uint8_t BYTE;
typedef uint16_t U16;
typedef uint32_t U32;
typedef int32_t S32;
typedef uint64_t U64;
#else
typedef unsigned char BYTE;
typedef unsigned short U16;
typedef unsigned int U32;
typedef signed int S32;
typedef unsigned long long U64;
#endif
#endif /* LZ4IO_ENABLE_SPARSE_FILE */
/****************************
* OS-specific Includes
*****************************/
@ -198,6 +219,7 @@ int LZ4IO_setSparseFile(int yes)
static int isSparse(const void* p, size_t size)
{
#if 0
const char* p8 = p;
for(; size; --size)
{
@ -208,6 +230,30 @@ static int isSparse(const void* p, size_t size)
++p8;
}
return 1;
#else
const U64* p64 = (const U64*) p;
const char* p8 = (const char*) p;
const size_t n = size / sizeof(*p64);
size_t i;
for (i = 0; i < n; ++i)
{
if (p64[i] != 0)
{
return 0;
}
}
for(i = n * sizeof(*p64); i < size; ++i)
{
if (p8[i] != 0)
{
return 0;
}
}
return 1;
#endif
}
#endif /* LZ4IO_ENABLE_SPARSE_FILE */