endian.c File Reference

Byte swapping between little and big endian. More...

#include "tpcclibConfig.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <math.h>
#include "tpcextensions.h"

Go to the source code of this file.

Functions
int	endianness ()
int	endianLittle ()
void	swap (void *from, void *to, int size)
void	swabip (void *buf, int size)
void	swawbip (void *buf, int size)
void	swawip (void *buf, int size)
void	swap64ip (void *buf, unsigned long long size)
void	swap32ip (void *buf, unsigned long long size)
void	swap16ip (void *buf, unsigned long long size)

Detailed Description

Byte swapping between little and big endian.

Author

Vesa Oikonen

Definition in file endian.c.

Function Documentation

endianLittle()

int endianLittle

(

)

Check whether current platform uses little endian byte order.

See also

swap, swabip, swawbip, swawip

Returns

Returns 1, if current platform is little endian, and 0 if not.

Definition at line 53 of file endian.c.

{
  //int x=1;
  //if(*(char *)&x==1) return(1); else return(0);
  if(endianness()==ENDIAN_LITTLE) return(1); else return(0);
}

Referenced by anaReadHeader(), dcmFileWrite(), dcmitemGetInt(), dcmitemGetReal(), dcmReadFileTag(), dcmReadFileVL(), dcmReadFileVRVL(), dcmValueString(), dcmWriteFileTag(), dcmWriteFileVRVL(), ecatMListRead(), ecatReadMainheader(), ecatWriteMainheader(), imgReadNifti(), imgSetNiftiHeader(), niftiReadHeader(), and niftiWriteHeader().

endianness()

int endianness

(

)

Detect endianness at run-time. From https://sourceforge.net/p/predef/wiki/Endianness/

Returns

Returns ENDIAN_UNKNOWN, ENDIAN_BIG, ENDIAN_LITTLE, ENDIAN_BIG_WORD, or ENDIAN_LITTLE_WORD.

Definition at line 26 of file endian.c.

{
  union {
    uint32_t value;
    uint8_t data[sizeof(uint32_t)];
  } number;
 
  number.data[0] = 0x00;
  number.data[1] = 0x01;
  number.data[2] = 0x02;
  number.data[3] = 0x03;
 
  switch (number.value) {
    case UINT32_C(0x00010203): return ENDIAN_BIG;
    case UINT32_C(0x03020100): return ENDIAN_LITTLE;
    case UINT32_C(0x02030001): return ENDIAN_BIG_WORD;
    case UINT32_C(0x01000302): return ENDIAN_LITTLE_WORD;
    default:                   return ENDIAN_UNKNOWN;
  }
}

Referenced by endianLittle().

swabip()

void swabip	(	void *	buf,
		int	size )

In-place swab, replaces the non-ANSI function swab(), which may not work if data is overlapping.

See also

swawbip, swawip, swap, endianLittle

Parameters

buf	Pointer to memory
size	Size of buf in bytes

Definition at line 115 of file endian.c.

  {
  if(buf==NULL) return;
 
  int i;
  unsigned char c;
 
  for(i=1; i<size; i+=2) {
    c=*((unsigned char *)buf+i);
    *((unsigned char *)buf+i)=*((unsigned char *)buf+(i-1));
    *((unsigned char *)buf+(i-1))=c;
  }
}

Referenced by anaReadHeader(), dcmFileWrite(), dcmWriteFileTag(), niftiReadHeader(), and niftiWriteHeader().

swap()

void swap	(	void *	from,
		void *	to,
		int	size )

Swap the specified short int, int, long int, float, or double from little endian to big endian or vice versa.

Arguments are allowed to overlap.

See also

swawbip, swabip, swawip, endianLittle

Parameters

from	Pointer to a short int, int, long int, float, or double variable.
to	Pointer to a short int, int, long int, float, or double variable.
size	Size of from and to (byte nr) must be 1, 2, 4 or 8.

Definition at line 69 of file endian.c.

  {
  if(from==NULL || to==NULL) return;
 
  unsigned char c;
  unsigned short int s;
  unsigned long l;
  
  switch(size) {
    case 1:
      *(char *)to=*(char *)from;
      break;
    case 2:
      c=*(unsigned char *)from;
      *(unsigned char *)to = *((unsigned char *)from+1);
      *((unsigned char *)to+1) = c; 
      /*swab(from, to, size); // NOT ANSI */
      break;
    case 4:
      s=*(unsigned short *)from;
      *(unsigned short *)to = *((unsigned short *)from+1);
      *((unsigned short *)to+1) = s;
      swap((char*)to, (char*)to, 2);
      swap((char*)((unsigned short *)to+1), (char*)((unsigned short *)to+1), 2);
      break;
    case 8:
      l=*(unsigned long *)from;
      *(unsigned long *)to = *((unsigned long *)from+1);
      *((unsigned long *)to+1) = l;
      swap((char *)to, (char *)to, 4);
      swap((char*)((unsigned long *)to+1), (char*)((unsigned long *)to+1), 4);
      break;
  }
}

Referenced by dcmitemGetInt(), dcmitemGetReal(), dcmReadFileTag(), dcmReadFileVL(), dcmReadFileVRVL(), dcmValueString(), dcmWriteFileVRVL(), and swap().

swap16ip()

void swap16ip	(	void *	buf,
		unsigned long long	size )

In-place big-little endian swapping of an array of 16 bit (2 byte) integers.

See also

swap32ip, swap64ip, endianLittle

Parameters

buf	Pointer to memory.
size	Nr of 16 bit values in the array.

Definition at line 234 of file endian.c.

  {
  if(buf==NULL || size==0) return;
 
  unsigned long long int i;
  unsigned char c, *cptr;
 
  cptr=(unsigned char*)buf;
  for(i=0; i<size; i++, cptr+=2) {
    c=cptr[0]; cptr[0]=cptr[1]; cptr[1]=c;
  }
}

Referenced by imgReadNifti(), niftiReadHeader(), and niftiWriteHeader().

swap32ip()

void swap32ip	(	void *	buf,
		unsigned long long	size )

In-place big-little endian swapping of an array of 32 bit (4 byte) integers or floating point values.

See also

swap16ip, swap64ip, endianLittle

Parameters

buf	Pointer to memory.
size	Nr of 32 bit values in the array.

Definition at line 210 of file endian.c.

  {
  if(buf==NULL || size==0) return;
 
  unsigned long long int i;
  unsigned char c, *cptr;
 
  cptr=(unsigned char*)buf;
  for(i=0; i<size; i++, cptr+=4) {
    c=cptr[0]; cptr[0]=cptr[3]; cptr[3]=c;
    c=cptr[1]; cptr[1]=cptr[2]; cptr[2]=c;
  }
}

Referenced by imgReadNifti(), niftiReadHeader(), and niftiWriteHeader().

swap64ip()

void swap64ip	(	void *	buf,
		unsigned long long	size )

In-place big-little endian swapping of an array of 64 bit (8 byte) integers or floating point values.

See also

swap32ip, swap16ip, endianLittle

Parameters

buf	Pointer to memory.
size	Nr of 64 bit values in the array.

Definition at line 184 of file endian.c.

  {
  if(buf==NULL || size==0) return;
 
  unsigned long long int i;
  unsigned char c, *cptr;
 
  cptr=(unsigned char*)buf;
  for(i=0; i<size; i++, cptr+=8) {
    c=cptr[0]; cptr[0]=cptr[7]; cptr[7]=c;
    c=cptr[1]; cptr[1]=cptr[6]; cptr[6]=c;
    c=cptr[2]; cptr[2]=cptr[5]; cptr[5]=c;
    c=cptr[3]; cptr[3]=cptr[4]; cptr[4]=c;
  }
}

Referenced by imgReadNifti(), niftiReadHeader(), and niftiWriteHeader().

swawbip()

void swawbip	(	void *	buf,
		int	size )

In-place swab and swaw, switches words and bytes from an array of 4-byte ints or floats.

See also

swawip, swabip, swap, endianLittle

Parameters

buf	Pointer to memory
size	Size of buf in bytes

Definition at line 138 of file endian.c.

  {
  if(buf==NULL) return;
 
  int i;
  unsigned char c, *cptr;
 
  cptr=(unsigned char*)buf;
  for(i=0; i<size; i+=4, cptr+=4) {
    c=cptr[0]; cptr[0]=cptr[3]; cptr[3]=c;
    c=cptr[1]; cptr[1]=cptr[2]; cptr[2]=c;
  }
}

Referenced by anaReadHeader(), ecatMListRead(), niftiReadHeader(), and niftiWriteHeader().

swawip()

void swawip	(	void *	buf,
		int	size )

In-place swaw, switches words (but not bytes) from an array of 4-byte ints or floats.

See also

swawbip, swabip, swap, endianLittle

Parameters

buf	Pointer to memory
size	Size of buf in bytes

Definition at line 161 of file endian.c.

  {
  if(buf==NULL) return;
 
  int i;
  unsigned short int s, *sptr;
 
  sptr=(unsigned short int*)buf;
  for(i=0; i<size; i+=4, sptr+=2) {
    s=sptr[0]; sptr[0]=sptr[1]; sptr[1]=s;
  }
}