llvm-6502/lib/System
2004-11-05 22:15:36 +00:00
..
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LICENSE.TXT
Makefile Change Library Names Not To Conflict With Others When Installed 2004-10-27 23:18:45 +00:00
MappedFile.cpp First version of the MappedFile abstraction for operating system idependent 2004-10-04 11:08:32 +00:00
Memory.cpp Provide initial implementations of Memory and Process concepts for various 2004-09-11 04:59:30 +00:00
Path.cpp Provide initial implementations of Memory and Process concepts for various 2004-09-11 04:59:30 +00:00
Process.cpp Provide initial implementations of Memory and Process concepts for various 2004-09-11 04:59:30 +00:00
Program.cpp
README.txt Abbreviate the long descriptions which are now in docs/SystemLibrary.html. 2004-08-30 02:03:51 +00:00
Signals.cpp Initial platform independent implementation of operating system concept 2004-08-29 19:22:48 +00:00
SysConfig.cpp Add a new abstraction, SysConfig for platform independent system 2004-08-31 17:43:29 +00:00
TimeValue.cpp Initial implementation of the TimeValue abstraction. 2004-09-24 23:25:19 +00:00

Design Of lib/System
====================

The software in this directory is designed to completely shield LLVM from any
and all operating system specific functionality. It is not intended to be a
complete operating system wrapper (such as ACE), but only to provide the
functionality necessary to support LLVM.

The software located here, of necessity, has very specific and stringent design
rules. Violation of these rules means that cracks in the shield could form and
the primary goal of the library is defeated. By consistently using this library,
LLVM becomes more easily ported to new platforms since the only thing requiring 
porting is this library.

Complete documentation for the library can be found in the file:
  llvm/docs/SystemLibrary.html 
or at this URL:
  http://llvm.org/docs/SystemLibrary.html

While we recommend that you read the more detailed documentation, for the 
impatient, here's a high level summary of the library's requirements.

 1. No system header files are to be exposed through the interface.
 2. Std C++ and Std C header files are okay to be exposed through the interface.
 3. No exposed system-specific functions.
 4. No exposed system-specific data.
 5. Data in lib/System classes must use only simple C++ intrinsic types.
 6. Errors are handled by throwing std::string *only*.
 7. Library must not throw any exceptions except std::string.
 8. Interface functions must not have throw() specifications.
 9. No duplicate function impementations are permitted within an operating
    system class.

To accomplish these requirements, the library has numerous design criteria that 
must be satisfied. Here's a high level summary of the library's design criteria:

 1. No unused functionality (only what LLVM needs)
 2. High-Level Interfaces
 3. Use Opaque Classes
 4. Common Implementations</a></li>
 5. Multiple Implementations</a></li>
 6. Minimize Memory Allocation</a></li>
 7. No Virtual Methods