It's assembly code that generates machine code at runtime! Specifically, it will generate a Horner scheme polynomial evaluator for any degree polynomial you want, as long as it's less than 13. (More than that and we start to run out of xmm registers.)
Sample run:
bash-3.2$ git clone https://github.com/davidad/fpew
Cloning into 'fpew'...
bash-3.2$ cd fpew
bash-3.2$ make
nasm -f macho64 fpew.asm
gcc fpew_test.c fpew.o -o fpew_test
bash-3.2$ ./fpew_test
exp(0.000) = 1.0000000
exp(0.250) = 1.2840254
exp(0.500) = 1.6487213
exp(0.750) = 2.1170000
exp(1.000) = 2.7182818
exp(1.250) = 3.4903430
exp(1.500) = 4.4816891
exp(1.750) = 5.7546026
exp(2.000) = 7.3890559
exp(2.250) = 9.4877347
exp(2.500) = 12.1824888
exp(2.750) = 15.6426121
exp(3.000) = 20.0854686
exp(3.250) = 25.7901261
exp(3.500) = 33.1148359
exp(3.750) = 42.5194293