mrg32k3a uses double float for integer arithmetic because it was designed (like poly1305) back when computers were mostly 32 bit, and C compilers didn't reliabl

mrg32k3a uses double float for integer arithmetic because it was designed (like poly1305) back when computers were mostly 32 bit, and C compilers didn't reliably expose 64 bit operations. It's easy to implement with 32-bit integer arithmetic in assembly, and trivial in C with 64-bit integers.