Emulator vs simulator performance

[Thomas Okken]

(06-05-2020 03:45 PM)J-F Garnier Wrote:  But Free42 is written in C, not assembly language, so the comparison is fair.
On the other hand, in this particular benchmark, we can expect a significant part of the time is spent in arithmetic operations that are in asm in the HP-42S, not sure in the Intel 35-digit library.

The Intel Decimal Floating-Point Math Library is written in C, and works using 64-bit integer operations under the hood. I don't think there's any assembly language in there but I haven't really looked for it... but when building for ARM, there definitely isn't since that is not a supported target at all, and I had to do a bit of hacking to even get it to build for Android and iOS.

When built for 32-bit targets, the 64-bit integer operations are compiled into multiple 32-bit operations, and that might benefit from coding it in assembly instead to eliminate duplicate operations (e.g. a 64-bit integer multiplication requires four 32-bit multiplications in general, but the special case of squaring a 64-bit number can be done using only three 32-bit multiplications), but this was not done. Free42 for Windows is a 32-bit app, and the Android and iOS versions contain 32-bit and 64-bit code, running the 32-bit code on 32-bit platforms and running 64-bit code otherwise.