This entry requires SDL2 to be installed. See FAQ 3.8: How do I compile an IOCCC entry that requires SDL1 or SDL2? if you don’t have it installed and don’t know how to do so.
make./prog./prog ioccc.txt
./prog prog.c
./prog sand.txt
./prog sand.alt.txtNOTE: these invocations will take quite some time to finish.
Can you explain the behavior of the program when ioccc.txt is given to it as input?
How would the description of the state machine look like when translated from Polynomish to English?
This entry graphically displays a simulation of sand falling. It uses SDL to draw the interface.
The code makes the following assumptions about the underlying system:
double is an IEEE 754 floating-point type and sizeof(double)==8.In order to simulate the motion of the sand, a cellular automaton is used. The
state transition table is not stored directly. Instead, the program stores the
coefficients of a polynomial that map each state to the correct one. These
coefficients are stored as raw hexadecimal in the V[] array, and they are
reinterpreted as doubles when used. This allows more numeric precision in fewer
characters (base 16 > base 10), and makes the purpose of the array less clear.
The code is laid out graphically as a bucket pouring sand, and it is far easier to observe this high-level layout than the code’s actual function.
The preprocessor is used to both obfuscate the code as a whole and abbreviate the calls to SDL. Additionally, throughout the code, the variables were named so that they are short and easily confused with each other.