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moab::SysUtil Namespace Reference

Functions

void setmem (void *mem, const void *value, unsigned value_size, size_t num_elem)
 Similar to memset, but accepts values larger than 1 char.
long filesize (FILE *filp)
 Get size of file (if it is a regular file)
long filesize (std::ifstream &str)
 Get size of file (if it is a regular file)
void byteswap (void *data, unsigned value_size, size_t num_elem)
 Swap byte order (e.g. change from big-endian to little-endian)
static uint16_t swap_bytes (uint16_t value)
static uint32_t swap_bytes (uint32_t value)
static uint64_t swap_bytes (uint64_t value)
void byteswap2 (void *data, size_t num_elem)
 Alternate byteswap optimized for 2-byte values.
void byteswap4 (void *data, size_t num_elem)
 Alternate byteswap optimized for 4-byte values.
void byteswap8 (void *data, size_t num_elem)
 Alternate byteswap optimized for 8-byte values.
bool little_endian ()
 Check if platform is little-endian.
bool big_endian ()
 Check if platform is big-endian.
template<typename T >
void byteswap (T *data, size_t num_elem)
 Type-specific byte swap.

Variables

const uint64_t m64b1 = 0xFF
const uint64_t m64b2 = m64b1 << 8
const uint64_t m64b3 = m64b1 << 16
const uint64_t m64b4 = m64b1 << 24
const uint64_t m64b5 = m64b1 << 32
const uint64_t m64b6 = m64b1 << 40
const uint64_t m64b7 = m64b1 << 48

Function Documentation

bool moab::SysUtil::big_endian ( ) [inline]

Check if platform is big-endian.

Check if platform is big-endian (least significant byte at lowest memory address.)

Definition at line 60 of file SysUtil.hpp.

{
  const unsigned one = 1;
  return !(((char*)&one)[sizeof(unsigned)-1]);
}
void moab::SysUtil::byteswap ( void *  data,
unsigned  value_size,
size_t  num_elem 
)

Swap byte order (e.g. change from big-endian to little-endian)

Reverse byte order or array of values.

Parameters:
dataPointer to beginning of memory block to modify
values_sizeSize of one value
num_elemNumber of values of size 'value_size' in 'data'

Definition at line 63 of file SysUtil.cpp.

{
  char* mem = reinterpret_cast<char*>(data);
  char* const end = mem + value_size * num_elem;
  for ( ; mem < end; mem += value_size) {
    unsigned i = 0, j = value_size - 1;
    while (i < j)
      std::swap( mem[i++], mem[j--] );
  }
}
template<typename T >
void moab::SysUtil::byteswap ( T *  data,
size_t  num_elem 
) [inline]

Type-specific byte swap.

Definition at line 84 of file SysUtil.hpp.

{
  switch (sizeof(T)) {
    case 1:
      break;
    case 2:  
      byteswap2( data, num_elem ); 
      break;
    case 4:  
      byteswap4( data, num_elem ); 
      break;
    case 8: 
      byteswap8( data, num_elem ); 
      break;
    default: 
      byteswap( data, sizeof(T), num_elem ); 
      break;
  }
}
void moab::SysUtil::byteswap2 ( void *  data,
size_t  num_elem 
)

Alternate byteswap optimized for 2-byte values.

Definition at line 140 of file SysUtil.cpp.

{
  uint16_t* mem = reinterpret_cast<uint16_t*>(data);
  uint16_t* end = mem + num_elem;
  for (; mem < end; ++mem)
    *mem = swap_bytes( *mem );
}
void moab::SysUtil::byteswap4 ( void *  data,
size_t  num_elem 
)

Alternate byteswap optimized for 4-byte values.

Definition at line 148 of file SysUtil.cpp.

{
  uint32_t* mem = reinterpret_cast<uint32_t*>(data);
  uint32_t* end = mem + num_elem;
  for (; mem < end; ++mem)
    *mem = swap_bytes( *mem );
}
void moab::SysUtil::byteswap8 ( void *  data,
size_t  num_elem 
)

Alternate byteswap optimized for 8-byte values.

Definition at line 156 of file SysUtil.cpp.

{
  if (sizeof(void*) >= 8) {
    uint64_t* mem = reinterpret_cast<uint64_t*>(data);
    uint64_t* end = mem + num_elem;
    for (; mem < end; ++mem)
      *mem = swap_bytes( *mem );
  }
  else {
    uint32_t* mem = reinterpret_cast<uint32_t*>(data);
    uint32_t* end = mem + 2*num_elem;
    for (; mem < end; mem += 2) {
      uint32_t tmp = swap_bytes( mem[0] );
      mem[0] = swap_bytes( mem[1] );
      mem[1] = tmp;
    }
  }
}
long moab::SysUtil::filesize ( FILE *  filp)

Get size of file (if it is a regular file)

Get size of regular file.

Returns:
- file size if known
  • -1 if file size cannot be determined (e.g. a pipe)
  • -2 if an unexpected failure occured (may indicate change in file position.)

Definition at line 29 of file SysUtil.cpp.

{
  long curr_pos = ftell( filp );
  if (fseek( filp, 0, SEEK_END ))
    return -1;
  
  long length = ftell( filp );
  if (fseek( filp, curr_pos, SEEK_SET))
  {
    assert(0); 
    return -2;
  }
  
  return length;
}
long moab::SysUtil::filesize ( std::ifstream &  str)

Get size of file (if it is a regular file)

Get size of regular file.

Returns:
- file size if known
  • -1 if file size cannot be determined (e.g. a pipe)
  • -2 if an unexpected failure occured (may indicate change in file position.)

Definition at line 46 of file SysUtil.cpp.

{
  std::istream::pos_type curr_pos = str.tellg();
  if (!str.seekg( 0, std::ios_base::end ))
    return -1;
  
  long length = static_cast<long>(str.tellg());
  if (!str.seekg( curr_pos, std::ios_base::beg ))
  {
    assert(0);
    return -2;
  }
  
  return length;
}
bool moab::SysUtil::little_endian ( ) [inline]

Check if platform is little-endian.

Check if platform is little-endian (least significant byte at highest memory address.)

Definition at line 49 of file SysUtil.hpp.

{
  const unsigned one = 1;
  return !*((char*)&one);
}
void moab::SysUtil::setmem ( void *  mem,
const void *  value,
unsigned  value_size,
size_t  num_elem 
)

Similar to memset, but accepts values larger than 1 char.

Set block of memory to repeating copies of a sequene of bytes.

Parameters:
memPointer to start of memory block to initialize
valueByte sequence to initialize mem with
value_sizeSize of 'value'
num_elemSize of 'mem' as a multiple of value_size (the number of copies of 'value' to write into 'mem'.)

Definition at line 15 of file SysUtil.cpp.

{
  if (!num_elem)
    return;
  
  char* array = reinterpret_cast<char*>(mem);
  memcpy( array, value, value_size );
  size_t count;
  for (count = 1; count*2 < num_elem; count *= 2)
    memcpy( array + count * value_size, array, count * value_size );
  memcpy( array + count * value_size, array, (num_elem - count) * value_size );
}
static uint16_t moab::SysUtil::swap_bytes ( uint16_t  value) [inline, static]

Definition at line 74 of file SysUtil.cpp.

{
  return (value >> 8) | (value << 8);
}
static uint32_t moab::SysUtil::swap_bytes ( uint32_t  value) [inline, static]

Definition at line 79 of file SysUtil.cpp.

{
  return ((value /*& (uint32_t)0xFF000000*/) >> 24) |
         ((value   & (uint32_t)0x00FF0000  ) >>  8) |
         ((value   & (uint32_t)0x0000FF00  ) <<  8) |
         ((value /*& (uint32_t)0X000000FF*/) << 24);
}
static uint64_t moab::SysUtil::swap_bytes ( uint64_t  value) [inline, static]

Definition at line 96 of file SysUtil.cpp.

{
  return ((value /*& m64b8*/) >> 56) |
         ((value   & m64b7  ) >> 40) |
         ((value   & m64b6  ) >> 24) |
         ((value   & m64b5  ) >>  8) |
         ((value   & m64b4  ) <<  8) |
         ((value   & m64b3  ) << 24) |
         ((value   & m64b2  ) << 40) |
         ((value /*& m64b1*/) << 56);
}

Variable Documentation

const uint64_t moab::SysUtil::m64b1 = 0xFF

Definition at line 87 of file SysUtil.cpp.

const uint64_t moab::SysUtil::m64b2 = m64b1 << 8

Definition at line 88 of file SysUtil.cpp.

const uint64_t moab::SysUtil::m64b3 = m64b1 << 16

Definition at line 89 of file SysUtil.cpp.

const uint64_t moab::SysUtil::m64b4 = m64b1 << 24

Definition at line 90 of file SysUtil.cpp.

const uint64_t moab::SysUtil::m64b5 = m64b1 << 32

Definition at line 91 of file SysUtil.cpp.

const uint64_t moab::SysUtil::m64b6 = m64b1 << 40

Definition at line 92 of file SysUtil.cpp.

const uint64_t moab::SysUtil::m64b7 = m64b1 << 48

Definition at line 93 of file SysUtil.cpp.

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