Dogcows Code - chaz/yoink/blob - src/stlplus/persistence/persistent_float.cpp

   1 ////////////////////////////////////////////////////////////////////////////////
   2
   3 //   Author:    Andy Rushton
   4 //   Copyright: (c) Southampton University 1999-2004
   5 //              (c) Andy Rushton           2004-2009
   6 //   License:   BSD License, see ../docs/license.html
   7
   8 ////////////////////////////////////////////////////////////////////////////////
   9 #include "persistent_float.hpp"
  10
  11 ////////////////////////////////////////////////////////////////////////////////
  12 // Macro for mapping either endian data onto little-endian addressing to make
  13 // my life easier in writing this code! I think better in little-endian mode
  14 // so the macro does nothing in that mode but maps little-endian onto
  15 // big-endian addressing in big-endian mode
  16 // TODO - make this compile-time configurable
  17
  18 #define INDEX(index) ((context.little_endian()) ? (index) : ((bytes) - (index) - 1))
  19
  20 /////////////////////////////////////////////////////////////////////
  21 // floating point types
  22 // format: {size}{byte}*size
  23 // ordering is msB first
  24
  25 // this uses a similar mechanism to integer dumps. However, it is not clear how
  26 // the big-endian and little-endian argument applies to multi-word data so
  27 // this may need reworking by splitting into words and then bytes.
  28
  29 namespace stlplus
  30 {
  31
  32   static void dump_float(stlplus::dump_context& context, unsigned bytes, unsigned char* data)
  33     throw(stlplus::persistent_dump_failed)
  34   {
  35     unsigned i = bytes;
  36     // put the size
  37     context.put((unsigned char)i);
  38     // and put the bytes
  39     while(i--)
  40       context.put(data[INDEX(i)]);
  41   }
  42
  43   static void restore_float(stlplus::restore_context& context, unsigned bytes, unsigned char* data)
  44     throw(stlplus::persistent_restore_failed)
  45   {
  46     // get the dumped size from the file
  47     unsigned dumped_bytes = (unsigned)context.get();
  48     // get the bytes from the file
  49     unsigned i = dumped_bytes;
  50     while(i--)
  51     {
  52       int ch = context.get();
  53       if (i < bytes)
  54         data[INDEX(i)] = (unsigned char)ch;
  55     }
  56     // however, if the dumped size was different I don't know how to map the formats, so give an error
  57     if (dumped_bytes != bytes)
  58       throw stlplus::persistent_restore_failed(std::string("size mismatch"));
  59   }
  60
  61 } // end namespace stlplus
  62
  63   ////////////////////////////////////////////////////////////////////////////////
  64   // exported functions which simply call the low-level byte-dump and byte-restore routines above
  65
  66 void stlplus::dump_float(stlplus::dump_context& context, const float& data) throw(stlplus::persistent_dump_failed)
  67 {
  68   stlplus::dump_float(context, sizeof(float), (unsigned char*)&data);
  69 }
  70
  71 void stlplus::restore_float(restore_context& context, float& data) throw(stlplus::persistent_restore_failed)
  72 {
  73   stlplus::restore_float(context, sizeof(float), (unsigned char*)&data);
  74 }
  75
  76 void stlplus::dump_double(stlplus::dump_context& context, const double& data) throw(stlplus::persistent_dump_failed)
  77 {
  78   stlplus::dump_float(context, sizeof(double), (unsigned char*)&data);
  79 }
  80
  81 void stlplus::restore_double(restore_context& context, double& data) throw(stlplus::persistent_restore_failed)
  82 {
  83   stlplus::restore_float(context, sizeof(double), (unsigned char*)&data);
  84 }
  85
  86 ////////////////////////////////////////////////////////////////////////////////