hecmw_vis_endian.c

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/*****************************************************************************
 * Copyright (c) 2019 FrontISTR Commons
 * This software is released under the MIT License, see LICENSE.txt
 *****************************************************************************/
 
#include "hecmw_vis_endian.h"
 
static long _TestEndian = 1;
 
int IsLittleEndian(void) { return *(char*)&_TestEndian; }
 
/******************************************************************************
  FUNCTION: SwapEndian
  PURPOSE: Swap the byte order of a structure
  EXAMPLE: float F=123.456;; SWAP_FLOAT(F);
 ******************************************************************************/
 
void* SwapEndian(void* Addr, const int Nb) {
  static char Swapped[16];
  switch (Nb) {
    case 2:
      Swapped[0] = *((char*)Addr + 1);
      Swapped[1] = *((char*)Addr);
      break;
    case 3: /* As far as I know, 3 is used only with RGB images */
      Swapped[0] = *((char*)Addr + 2);
      Swapped[1] = *((char*)Addr + 1);
      Swapped[2] = *((char*)Addr);
      break;
    case 4:
      Swapped[0] = *((char*)Addr + 3);
      Swapped[1] = *((char*)Addr + 2);
      Swapped[2] = *((char*)Addr + 1);
      Swapped[3] = *((char*)Addr);
      break;
    case 8:
      Swapped[0] = *((char*)Addr + 7);
      Swapped[1] = *((char*)Addr + 6);
      Swapped[2] = *((char*)Addr + 5);
      Swapped[3] = *((char*)Addr + 4);
      Swapped[4] = *((char*)Addr + 3);
      Swapped[5] = *((char*)Addr + 2);
      Swapped[6] = *((char*)Addr + 1);
      Swapped[7] = *((char*)Addr);
      break;
    case 16:
      Swapped[0]  = *((char*)Addr + 15);
      Swapped[1]  = *((char*)Addr + 14);
      Swapped[2]  = *((char*)Addr + 13);
      Swapped[3]  = *((char*)Addr + 12);
      Swapped[4]  = *((char*)Addr + 11);
      Swapped[5]  = *((char*)Addr + 10);
      Swapped[6]  = *((char*)Addr + 9);
      Swapped[7]  = *((char*)Addr + 8);
      Swapped[8]  = *((char*)Addr + 7);
      Swapped[9]  = *((char*)Addr + 6);
      Swapped[10] = *((char*)Addr + 5);
      Swapped[11] = *((char*)Addr + 4);
      Swapped[12] = *((char*)Addr + 3);
      Swapped[13] = *((char*)Addr + 2);
      Swapped[14] = *((char*)Addr + 1);
      Swapped[15] = *((char*)Addr);
      break;
  }
  return (void*)Swapped;
}