diff options
| -rw-r--r-- | src/lisp.h | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/src/lisp.h b/src/lisp.h index b410ee45aed..5aee80cea11 100644 --- a/src/lisp.h +++ b/src/lisp.h @@ -511,10 +511,14 @@ enum Lisp_Fwd_Type to add a new Lisp_Misc, extend the Lisp_Misc_Type enumeration. For a Lisp_Misc, you will also need to add your entry to union - Lisp_Misc (but make sure the first word has the same structure as + Lisp_Misc, but make sure the first word has the same structure as the others, starting with a 16-bit member of the Lisp_Misc_Type - enumeration and a 1-bit GC markbit) and make sure the overall size - of the union is not increased by your addition. + enumeration and a 1-bit GC markbit. Also make sure the overall + size of the union is not increased by your addition. The latter + requirement is to keep Lisp_Misc objects small enough, so they + are handled faster: since all Lisp_Misc types use the same space, + enlarging any of them will affect all the rest. If you really + need a larger object, it is best to use Lisp_Vectorlike instead. For a new pseudovector, it's highly desirable to limit the size of your data type by VBLOCK_BYTES_MAX bytes (defined in alloc.c). |