BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  What's an Emulator?          BorlandTalk.com Forum Index -> C++ Builder (Non-Technical) View previous topic :: View next topic   Author Message Roddy Pratt Guest Posted: Thu May 13, 2004 10:04 pm    Post subject: What's an Emulator? See: http://www.google.co.uk/search?hl=en&lr=&oi=defmore&q=define:emulator I can't see anything there that fits my understanding of gcc under win32... The key aspect for me is that gcc is specifically compiled and linked to a win32 .exe. There are certain to be some software "shims" converting idionsyncracies of the win32 api functions used into the (different) idiosyncracies expected by a *nix application, but this is just the normal metaphor of separating interface from implementation... [FWIW, I once wrote a 68K/6502 emulator. That's emulating a 68000 on a Commodore C64, NOT vice-versa!] - Roddy Back to top Ed Mulroy [TeamB] Guest Posted: Thu May 13, 2004 10:28 pm    Post subject: Re: What's an Emulator? So you have concluded that emulating Linux under Windows is not emulating? The page whose link you provided does not agree with that. .. Ed Quote: Roddy Pratt wrote in message news:40a3f0f8 (AT) newsgroups (DOT) borland.com... See: http://www.google.co.uk/search?hl=en&lr=&oi=defmore&q=define:emulator I can't see anything there that fits my understanding of gcc under win32... The key aspect for me is that gcc is specifically compiled and linked to a win32 .exe. There are certain to be some software "shims" converting idionsyncracies of the win32 api functions used into the (different) idiosyncracies expected by a *nix application, but this is just the normal metaphor of separating interface from implementation... [FWIW, I once wrote a 68K/6502 emulator. That's emulating a 68000 on a Commodore C64, NOT vice-versa!] Back to top Roddy Pratt Guest Posted: Thu May 13, 2004 11:00 pm    Post subject: Re: What's an Emulator? "Ed Mulroy [TeamB]" <dont_email_me (AT) bitbuc (DOT) ket> wrote Quote: So you have concluded that emulating Linux under Windows is not emulating? The page whose link you provided does not agree with that. Ed, It's certainly possible to consider software "shims" like that to be 'emulators', but it's just not common practice. The standard c rtl is pretty much the native unix programming api - that's where it comes from. Does that mean that if I use the c rtl instead of 'native' win32 calls, I'm using an emulation? The term "emulator" often implies slow, probably interpreted, and somewhat "kludged". It's often used in a negative or derogatory way. That's why a number of people are taking issue with you on this. FYI, I do use gcc for cross-development, but I'd rather boil my head than use gcc for windows gui programming. Regards, Roddy int add_a_to_b(int a, int b) { return a+b;} int emulate_addition_of_a_to_b(int a, int b) { return a+b;} Back to top Ed Mulroy [TeamB] Guest Posted: Thu May 13, 2004 11:21 pm    Post subject: Re: What's an Emulator? Quote: The term "emulator" often implies slow, probably interpreted, and somewhat "kludged". It's often used in a negative or derogatory way. ... Maybe that is so, but that is not how I meant it. I meant emulator as in the normal term where it emulates either or both of operating system functionality or hardware, like the Windows emulator used with Borland's extended DOS programs or the 386 emulator in VM386. Quote: ...FYI, I do use gcc for cross-development, but I'd rather boil my head than use gcc for windows gui That may be another issue. If that is an IDE comment, I routinely develop for Windows from the command line using a text editor and make files. Quote: The standard c rtl is pretty much the native unix programming api ... Well, almost. Unix was written in C so the standard library inherently had what was in Unix. However things change so functions such as fread and fwrite which were not provided by Unix were provided and read and write which were provided by Unix were also in it. Later Unix split with some versions having fread and fwrite and others having both sets so it's kind of a historical museum of Unix. (Thankfully they did away with 'ps' when someone thought of naming it 'puts') However that is the 'programming api', the compiler supplied functions to deal with the OS. If the OS used any of function calls or MSDOS-like interrupts, IBM-style startio and testio calls or dedicated memory locations the compiler supplied functions remain the same. The interface to the OS is one issue. The OS supplies another layer which is what is needed to deal with its underlying schemes of doing things. If the interface supplied is for a different OS then the task of supplying is that of an emulator. .. Ed Quote: Roddy Pratt wrote in message news:40a3fe20 (AT) newsgroups (DOT) borland.com... Back to top Roddy Pratt Guest Posted: Fri May 14, 2004 12:04 am    Post subject: Re: What's an Emulator? Quote: I'd rather boil my head than use gcc for windows gui It's a RAD issue, more than an IDE one. And life's too short to build your own toolchains. That's why I use BCB. Quote: However that is the 'programming api', the compiler supplied functions to deal with the OS. If the OS used any of function calls or MSDOS-like interrupts, IBM-style startio and testio calls or dedicated memory locations the compiler supplied functions remain the same. "compiler-supplied"? - not sure I get this. The rtl functions are normally supplied from a library/dll at link/run time. While the c rtl is part of the language spec, it's rarely something compilers have much knowledge of, except for memcpy-style optimizations. Quote: The interface to the OS is one issue. The OS supplies another layer which is what is needed to deal with its underlying schemes of doing things. If the interface supplied is for a different OS then the task of supplying is that of an emulator. Ah! (light dawns) You're saying that the c++ rt library should be considered part of the OS, not part of the toolchain/application/whatever??, and that by effectively 'replacing' it with a different rtl with a different published interface, you're now emulating the os that 'defined' that interface? If I've got that right, then I'd disagree - I consider the c rtl part of the application rather than part of the OS. It all runs in my address space, and is accessed by nothing smarter than function calls. The OS boundary is normally trap-dispatched or similar. And by changing between two rtls, IMO you're just changing between two different abstraction layers. No hooking of traps or other trickery involved. - Roddy Back to top Chris Uzdavinis (TeamB) Guest Posted: Fri May 14, 2004 1:35 am    Post subject: Re: What's an Emulator? "Ed Mulroy [TeamB]" <dont_email_me (AT) bitbuc (DOT) ket> writes: Quote: So you have concluded that emulating Linux under Windows is not emulating? The page whose link you provided does not agree with that. If you can run _native_ linux binaries--that is, programs compiled with the intent to be run directly inside linux--under windows, unmodified, then it's emulation. Emulation is a run-time feature, not a compile time feature. If you have software library that emulates an interface, it's just software, and when it compiles it is now a 100% native application for the environment for which it was compiled. -- Chris (TeamB); Back to top Chris Uzdavinis (TeamB) Guest Posted: Fri May 14, 2004 1:37 am    Post subject: Re: What's an Emulator? "Roddy Pratt" <roddy at rascular dot com> writes: Quote: If I've got that right, then I'd disagree - I consider the c rtl part of the application rather than part of the OS. It all runs in my address space, and is accessed by nothing smarter than function calls. The OS boundary is normally trap-dispatched or similar. And by changing between two rtls, IMO you're just changing between two different abstraction layers. No hooking of traps or other trickery involved. Exactly! -- Chris (TeamB); Back to top Boian Mitov Guest Posted: Fri May 14, 2004 2:09 am    Post subject: Re: What's an Emulator? Ohhh boy ohhh boy.... Here we go again ;-) Ed Mulroy [TeamB] wrote: Quote: So you have concluded that emulating Linux under Windows is not emulating? The page whose link you provided does not agree with that. . 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