Programmatically check fixnum size

Question

Wikibook for Common Lisp says that fixnums are guaranteed to be able to hold integer values in [-2¹⁵; 2¹⁵-1] range and that it is implementation dependent. *features* can tell me if the host is 32 or 64-bit but a fixnum in Lisp does not cover the whole 32/64 bits. Is there a way to programmatically check what is the size of a fixnum in a CL implementation?

score 9 · Accepted Answer · answered Mar 16 '11 at 22:51

9

(integer-length most-negative-fixnum) will tell you.

answered Mar 16 '11 at 22:51

Xach

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Thanks. Clozure CL on my 64-bit openSUSE shows 60, so 4 bits are reserved for flags. – FilipK Mar 18 '11 at 10:56

Programmatically check fixnum size

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