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# Coding style guidelines
## Structure
The code is divided into the following directories:
* src/ - utility functions, tools
* game/ - game logic
* ui/ - UI implementations
* classic/ - the 1993 UI
* cmdline/ - experimental command line UI
* nop/ - dummy UI for tools
* hw/ - hardware abstraction
* sdl/ - libSDL
* 1/ - libSDL 1.2.x
* 2/ - libSDL 2.x
* alleg/ - Allegro
* 4/ - Allegro 4.x
* nop/ - dummy HW for tools
* os/ - Operating System; file paths
* unix/ - yay
* win32/ - boo
* msdos/ - wtf
Some facts:
* main is in hw/ (due to SDL)
* os/ knows nothing about game/, ui/ or hw/
* hw/ knows nothing about game/ or ui/
* game/ knows nothing about hw/
* ui/ is known via src/ui.h
* hw/ is known via src/hw.h
* os/ is known via src/os.h
* src/ knows game via the very narrow src/gameapi.h
(the exception is saveconv.c)
* ui/ knows all about game/
Different hw/ and ui/ implementations can be built with a single configure.
The resulting binaries follow a "1oom_$UI_$HW" naming convention.
## Style
- no tabs, 4 spaces for indentation
- always add the { } braces to if, do, while, for statements
- one space after a ',', if, do, while, for and return statements,
no space after function name:
if (func(4, 5) < 0) {
return (foo * 4) + 2;
}
- add spaces around +, -, *, /, =, == etc:
a = (22 + b * 4) / 7;
- have the opening brace on the same line as the statement,
unless the condition spills to multiple lines:
if (foo) {
...
}
if (1
&& really_long_name
&& (function_call(with_parameters) < and_a_comparison)
) {
...
}
- have the opening brace of a function in the next line:
int func(void)
{
...
}
- use C-style comments /* like here */
- function and variable names are lowercase with '_' for space
- defines and enums are UPPERCASE with '_' for space
- avoid global variables
- declare functions / data which are not used outside the module as static
- group static functions / data above others, separate with a /* --.. */ line
- avoid memory allocations after game startup
Do not use unsafe string functions like strcpy, strcat and sprintf. 1oom pbx
files may redefine most in-game strings, and besides, it's good practice.
There are replacement functions in src/lib.c which take an additional buffer
size argument and crash instead of overflowing the buffer.
Avoid declaring variables after the start of scope:
if (foo) {
int this_is_ok;
v = 123;
int this_is_frowned_upon;
...
}
Note that declaring the loop variable inside for is ok:
for (int i = 0; i < FOO; ++i) {
...
}
Otherwise, try to keep close to C89.
Avoid #ifdefs! No OS-specific #ifdefs are allowed in game/, ui/ or src/.
Acceptable ones include HAVE_SAMPLERATE etc and FEATURE_MODEBUG.
## On brevity
Comment only the unobvious or the big picture. Do not add inane comments like:
/* do stuff */
do_stuff();
Keep the commit message as one line of 70 characters or less. Do not end it
with a '.'. Save any explanatory paragraphs for the merge request.
Don't try to remove code that you don't think makes sense. It always has value
if it strictly matches the original.
## Portability
1oom is designed to be cross-platform and work on different Operating
Systems, processors and libraries. Bear this in mind when writing code.
Each hardware abstraction library will have its own directory in hw/.
Any and all of these must be buildable with one configure and produce
differently named binaries.
Do not use the `long` type (its size differs across platforms; use
`int` or `int64_t` depending on which you want).
Be careful with platform dependencies: do not use Windows API
functions outside os/win32/, for example. Do not use SDL outside of
hw/sdl/.
Tests for OS in configure.ac and use for example `IS_WINDOWS` instead of
the preprocessor `_WIN32`. The #defines can be used to identify the OS
if necessary. Try to avoid this if possible. Only consider them in hw/ or os/.
Hey, you there, OS X porter! Do not turn os/unix/ into an #ifdef shithole,
just copy it to os/osx/ and hack away.
Be careful of endianness! The the macros in bits.h to do endianness
conversion. Never assume that integer types have a particular byte
ordering. Similarly, never assume that fields inside a structure
are aligned in a particular way. This is most relevant when reading
or writing data to a file or a network pipe.
For signed integers, you shouldn’t assume that `(i >> n)` is the same as
`(i / (1 << n))`. However, most processors handle bitshifts of signed
integers properly, so it’s not a huge problem.
## GNU GPL and licensing
All code submitted to the project must be licensed under the GNU GPLv2 or a
compatible license.
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