[Octave-bug-tracker] [bug #41672] fread for "float" not matlab compatible

[Rik]

Follow-up Comment #5, bug #41672 (project octave):

I changed the documentation to show that "float" is not system-dependent, but
actually 32 bits (http://hg.savannah.gnu.org/hgweb/octave/rev/58435a400d4e).

The Matlab documentation for fread
(http://www.mathworks.com/help/matlab/ref/fread.html) has a table with all of
the sizes in bits and bytes for each type.  These are not platform dependent. 
Should the function "oct_data_conv::string_to_data_type (const std::string&
str)" in liboctave/util/data-conv.cc be re-written?

Here is an excerpt:


  if (s == "int8" || s == "integer*1")
    retval = dt_int8;
  else if (s == "uint8")
    retval = dt_uint8;
  else if (s == "int16" || s == "integer*2")
    retval = dt_int16;
  else if (s == "uint16")
    retval = dt_uint16;
  else if (s == "int32" || s == "integer*4")
    retval = dt_int32;
  else if (s == "uint32")
    retval = dt_uint32;
  else if (s == "int64" || s == "integer*8")
    retval = dt_int64;
  else if (s == "uint64")
    retval = dt_uint64;
  else if (s == "single" || s == "float32" || s == "real*4")
    retval = dt_single;
  else if (s == "double" || s == "float64" || s == "real*8")
    retval = dt_double;
  else if (s == "char" || s == "char*1")
    retval = dt_char;
  else if (s == "schar" || s == "signedchar")
    retval = dt_schar;
  else if (s == "uchar" || s == "unsignedchar")
    retval = dt_uchar;
  else if (s == "short")
    GET_SIZED_INT_TYPE (short, );
  else if (s == "ushort" || s == "unsignedshort")
    GET_SIZED_INT_TYPE (unsigned short, u);
  else if (s == "int")
    GET_SIZED_INT_TYPE (int, );
  else if (s == "uint" || s == "unsignedint")
    GET_SIZED_INT_TYPE (unsigned int, u);
  else if (s == "long")
    GET_SIZED_INT_TYPE (long, );
  else if (s == "ulong" || s == "unsignedlong")
    GET_SIZED_INT_TYPE (unsigned long, u);
  else if (s == "longlong")
    GET_SIZED_INT_TYPE (long long, );
  else if (s == "ulonglong" || s == "unsignedlonglong")
    GET_SIZED_INT_TYPE (unsigned long long, u);
  else if (s == "float")
    {
      if (sizeof (float) == sizeof (double))
        retval = dt_double;
      else
        retval = dt_single;
    }
  else if (s == "logical")
    retval = dt_logical;
  else
    (*current_liboctave_error_handler) ("invalid data type specified");


Given that the sizes are fixed, it seems like "schar", for example, should
return dt_int8 rather than dt_schar.  

This would also be the place to change unsigned long to return 32 bits.




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