On 2/9/06, The Fool <[EMAIL PROTECTED]> wrote: > > So I needed to create C++ class that would be used to create a static > copy of some data the program already Uses (but sometimes changes), for > which it would need to revert to its original state (it also non > contiguous). It also needs to be able to 'fiddle' with the data at the > byte/bit level. > > So I create part of the class, but when I tested it I got these weird > results. It seemed to be putting say integer (32bit) data bytes > backwards..
Sounds like an endian issue to me. Are you on a PC? Pentiums are little endian, so the LSByte is written first (ie: to the lowest address). Let's say you want to write the 32-bit hex integer value 0x76543210 to address 0. Most Significant Byte: 0x76 Least Significant Byte: 0x10 Address Byte ----------------------- 000000 0x10 000001 0x32 000002 0x54 000003 0x76 When the CPU reads an integer (or other 4-byte value), it automatically arranges the bytes around so they are MSB..LSB in the processor and the endian-ness is transparent to the user. But if you manipulate the individual bytes of a multi-byte value, you need to be aware of the endianness of the machine and deal with it accordingly. Now imagine the headaches when you have little endian hardware sharing raw data buffers with big endian hardware and welcome to my world. :-) I tried to be concise here - let me know if you want further elaboration. -Bryon Also, IIRC, a while back I posted the origin article of the big/little endian terms: "On Holy Wars and a Plea For Peace" if you're interested. _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
