[Txr-users] In GIT: (partially complete) bignum support!

[Kaz Kylheku]

TXR now has bignum integers.

Bignum integers can be used in the syntax. Constants too big to be 
fixnums (unboxed numbers that fit into the space
of a pointer, minus two tag bits) become heap-allocated bignums.

Bignums are properly hashed, printed, compared for different kinds of 
equality, and garbage collected.

However, the only arithmetic operation that supports them is the plus 
function. If you add two fixnums, and the result overflows, a bignum is 
created. If adding two bignums, or a bignum and fixnum, creates a 
number that is in the fixnum range, a fixnum is created.

I used Fromberger's MPI library, and added a bunch of patches to it. 
On x86_64, I made it use 64 bit "digits" (mpi_digit) and 128 bit 
integers (supported in gcc) for intermediate arithmetic results 
(mpi_word).

Cheers ...