◆ magic()

int tfxx::ioswap::magic ( const char *const cmagic )

Create a magic number from a character string. ,If $x_{i}=(\vec{x})_{i}$ represents the input character sequence cmagic and $N=4$ is the value of sizeof(int), then the return value will be

$\textrm{magic}(\vec{x}) =\sum\limits_{i=0}^{N-1} x_{i}\; 2^{8\; (N-1-i)} =x_{3}+256\; (x_{2}+256\; (x_{1}+256\; x_{0})).$

.

function to create the magic number

Parameters

cmagic 4-byte character sequence representing magic number (most restrictive: pass a const pointer to a const char) is pointer to character array of size sizeof(int)

Returns: The magic number representing the 4-byte character sequence on your system

See also: TEST: Fortran I/O and byte swapping.

Definition at line 59 of file ioswap.cc.

Referenced by cpu(), file_magic_test(), file_magic_write(), and tfxx::fortranio::FortranBinOutput::write_magic().

 {
   union {
     unsigned int uival;
     int ival;
   } out;
   union {
     char chr[sizeof(int)];
     unsigned char uchr[sizeof(int)];
   } in;
   const int& intsize=sizeof(int);
   for (int i=0; i<intsize; i++)
   { in.chr[i]=cmagic[i]; }
   out.uival=0;
   for (int i=0; i<intsize; i++)
   { out.uival=out.uival*256+in.uchr[i]; }
   return(out.ival);
 } // magic()

Here is the caller graph for this function: