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Diffstat (limited to 'JOURNAL')
| -rw-r--r-- | JOURNAL | 51 |
1 files changed, 50 insertions, 1 deletions
@@ -3,7 +3,7 @@ #title Toilet Lisp Development Diary #desc Random news and stuff about just another random pet project -; Time-stamp: <2008-08-02 13:54:33 mulk> +; Time-stamp: <2008-08-06 11:36:21 mulk> ; ; C-c i t insert-time-stamp ; C-c C-t muse-project-publish-this-file @@ -18,6 +18,55 @@ Context: [[http://matthias.benkard.de/toilet][The Toilet Lisp Project]]. ---- +* 2008-08-06, 11:08:30 CEST + +** Function Calling + +I'm pondering function call conventions. My current design looks like this: + +*** Entry Points + + - For each function, provide two distinct entry points: a trampoline + for use by C code and the “direct” entry point. + + - The direct entry point requires supplying the closure variable vector + to be passed explicitly as the first argument, while the trampoline + doesn't. + + - The trampoline uses the normal C calling convention. The direct + entry point may use a different one (it's not clear to me that LLVM + allows such, though). + +*** Arguments + + - All functions are varargs, because there is no other way to ensure + the safety of passing more arguments than are expected. Should we + provide yet a third entry point for unsafe code? + + - There is a thread-local global variable that controls the use of + multiple value returns. The caller sets it to 1 if they want to have + multiple values returned to them. In this case, the callee + immediately sets the variable to 0 again and before returning either + arranges for the thread-local variable to contain a pointer to a + vector of values (along with their number or an end-of-vector marker, + of course) or it leaves it as 0 if there is exactly one return value. + The caller is responsible for freeing the memory used by the return + vector. + +*** Return Values + + - (multiple-value-call ... (values ...)) is handled specially by the + compiler, because (values ...) isn't a function call. + +*** Foreign Functions + + - C functions may simply be placed in the global environment as-is as + long as they only take =id= arguments and return a single id value. + + - Other C functions are wrapped in a Lisp-to-C trampoline that does the + needed conversions of arguments and return values. + + * 2008-08-02, 13:46:14 CEST ** Exception Handling Crashes on Debian Systems |