Difference between revisions of "Portability issues"

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Portability Issues
The purpose of this article is to collect portability issues often encountered by roguelike programmers as well as possible solutions for these problems.
The purpose of this article is to collect portability issues often encountered by roguelike programmers as well as possible solutions for these problems.


== Memory ==
== Memory ==


* Memory in the [[processor's real mode]] is tight and inconveniently segmented.  Later models had a variety of schemes available for accessing [[expanded memory]] or [[extended memory]], but being maximally portable to this platform means using less than 640KB of RAM.
* Some [[Operating systems]], such as IRIX, allow the programs to read from a [[NULL address]], while others will [[segfault]] instantly.  Trying to write to a [[NULL address]] will hopefully always cause a [[segfault]]. (Except on many embedded systems.  The Gameboy Advance, for example, will not [[segfault]] on a [[NULL address]] write.)
* Some [[Operating Systems]] allow the programs to read from a [[NULL address]], while others will [[segfault]] instantly.  Trying to write to a [[NULL address]] will hopefully always cause a [[segfault]].


== Display ==
== Display ==


* Only the characters of the basic (7bit) ASCII character set are reasonable portable. Using characters from extended character sets (like the solid blocks from the IBM DOS character set) or characters which aren't classified as printable by the ASCII standard (like the smileys from IBM DOS) will probably cause problems.
* Only the characters of the basic (7bit) ASCII character set are reasonably portable. Using characters from extended character sets (like the solid blocks from the IBM DOS character set) or characters which aren't classified as printable by the ASCII standard (like the smileys from IBM DOS) will probably cause problems.
** Extensions to ASCII are not portable.  Unicode is portable, though, plus it includes all the old IBM DOS characters, though not necessarily at the same code points.
** Extensions to ASCII are not portable.  Unicode is portable, though, plus it includes all the old IBM DOS characters, though not necessarily at the same code points.
* [[Output libraries]] discusses the options you have.


== Filesystem ==
== Filesystem ==


* Some [[Operating Systems]] (such as any derive from or copy [[Unix]], or follow the [[POSIX]] standards) are case-sensitive as far as filenames are concerned.  Others (like [[DOS]] or [[Windows]]) aren't.  Still others (like [[Mac OS X]]) are inconsistent in their case-sensitivity or preservation. So, one shouldn't rely on any one case behavior for maximum portability.
* Some [[Operating systems]] (such as any that derive from or pattern [[UNIX]] or follow [[POSIX]] standards) are case-sensitive as far as filenames are concerned.  Others (like [[DOS]] or [[Windows]]) are case-insensitive.  Still others (like HFS , in common use on [[Mac OS X | OS X]]) preserve case but are insensitive to it. One shouldn't rely on any one case behavior to achieve maximum portability.
* There are [[Operating Systems]] that forbide using certain characters in the file names.
* There are [[Operating systems]] that forbid use of certain characters within file names, most often path separators (e.g., colons in Classic [[Mac OS]]). Other characters may require "escaping" in filename references.
* [[Operating Systems]] also can restrict the length of the filename or the total length of absolute path of file.
* [[Operating systems]] may also restrict filename length or the total length of an absolute filepath.
* [[DOS]] and [[Windows]] use different [[path separator character]].a ''backslash'' ("\"). rather than the ''slash'' ("/") character defined in [[POSIX]].
* [[DOS]] and [[Windows]] use backslash as their path separator while [[UNIX]] uses slash. Most Windows APIs will understand the forward slash as a path separator, however.
 
[[Category:Articles]]
== Input ==
 
* Use of the Escape key should be avoided, because escape is a [[special character]] for many of the terminals that roguelikes are traditionally played on.  These terminals sometimes must hold up an escape key to see if it should be processed or passed on, and that causes annoying delays in a user interface that uses Escape.
 
* Which characters are used to indicate the end of a line in text files is [[OS-specific]]. One has to be careful when [[parsing text files]].


== Mac OS X ==
== Sockets / Networking ==


* The current version of the standard [[Mac OS X]] terminal (Terminal.app) only supports 8 colors. Early versions of [[Mac OS X]] [[curses library]] did not support color at all.
If you use socket-related system calls directly, you will need to change your code a bit for different platforms:


== DOS ==
* [[Windows]] uses different header files under C/[[Cpp]]. The following will work under mingw32.
    #ifdef WIN32
        #include <winsock2.h>
        typedef int socklen_t;
    #else
        #include <sys/socket.h>
        #include <netinet/in.h>
        #include <arpa/inet.h>
        #include <netdb.h>
    #endif
* You will need to call the following before any standard socket code:
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2,2), &wsaData);
* And the following on exit:
    WSACleanup();
* And as a handy hint, sleep:
    #include <windows.h>
    #define sleep(n) Sleep(1000 * n)


* Filenames are limited to 8 characters + a 3 characters extension. Additionally filenames must not contain whitespace or [[DOS special characters]].
However, it is often a good idea to use a higher-level interface, such as SDL_net, instead. These are easier to work with and more portable.

Latest revision as of 02:31, 19 May 2017

The purpose of this article is to collect portability issues often encountered by roguelike programmers as well as possible solutions for these problems.

Memory

Display

  • Only the characters of the basic (7bit) ASCII character set are reasonably portable. Using characters from extended character sets (like the solid blocks from the IBM DOS character set) or characters which aren't classified as printable by the ASCII standard (like the smileys from IBM DOS) will probably cause problems.
    • Extensions to ASCII are not portable. Unicode is portable, though, plus it includes all the old IBM DOS characters, though not necessarily at the same code points.
  • Output libraries discusses the options you have.

Filesystem

  • Some Operating systems (such as any that derive from or pattern UNIX or follow POSIX standards) are case-sensitive as far as filenames are concerned. Others (like DOS or Windows) are case-insensitive. Still others (like HFS , in common use on OS X) preserve case but are insensitive to it. One shouldn't rely on any one case behavior to achieve maximum portability.
  • There are Operating systems that forbid use of certain characters within file names, most often path separators (e.g., colons in Classic Mac OS). Other characters may require "escaping" in filename references.
  • Operating systems may also restrict filename length or the total length of an absolute filepath.
  • DOS and Windows use backslash as their path separator while UNIX uses slash. Most Windows APIs will understand the forward slash as a path separator, however.

Sockets / Networking

If you use socket-related system calls directly, you will need to change your code a bit for different platforms:

  • Windows uses different header files under C/Cpp. The following will work under mingw32.
   #ifdef WIN32
       #include <winsock2.h>
       typedef int socklen_t;
   #else
       #include <sys/socket.h>
       #include <netinet/in.h>
       #include <arpa/inet.h>
       #include <netdb.h>
   #endif
  • You will need to call the following before any standard socket code:
   WSADATA wsaData;
   WSAStartup(MAKEWORD(2,2), &wsaData);
  • And the following on exit:
   WSACleanup();
  • And as a handy hint, sleep:
   #include <windows.h>
   #define sleep(n) Sleep(1000 * n)

However, it is often a good idea to use a higher-level interface, such as SDL_net, instead. These are easier to work with and more portable.