Re: [Emc-developers] on the integer question by Rene

[andy p. <bod...@gm...>]

On Sun, 7 Jun 2026 at 15:59, Luca Toniolo <lu...@ai...> wrote:

> Fair, the magnitude case is rare and I won't push it. But the behaviour at the limit differs. An integer counter wraps at a known point and we already reconstruct it: hal_extend_counter() extends limited-width counters to 64 bits with the usual modular trick, so the count just keeps going, no discontinuity, no lost counts. A float past 53 bits doesn't wrap, it degrades silently, x + 1 == x and the count eventually sticks, with no boundary to detect and nothing to recover. So where it matters, the integer keeps counting correctly and the float quietly loses count.

A getter/setter interface could warn/error at this point.
I _think_ that the underlying driver code would ask for a specific
type back from the interface, it would be absolutely _only_ the pins
that were all fungible doubles.
The motivation is to make HAL easier for users. Doing this would make
the conv_*_* components unnecessary. You can connect anything to
anything. (and you are on your own if that's a silly thing :-) )

> Either way, magnitude isn't the only reason for integer pins. It's also the values that aren't counts: registers, status and fault words, masks. Those don't round or wrap, the bit pattern just has to survive, which a double can't do. sserial already carries them as hal_u32_t pins for exactly that reason.

It does, but currently we have no 64-bit masks or registers.
Worst-case if those appear the driver component would have to provide
high-byte and low-byte HAL pins.

> One honest question: what would bitslice and bitmerge operate on without an integer type? Their job is word-to-bits and bits-to-word.

These would probably remain as 32-bit components. The pin-names would
be the same, they could be connected freely to any other HAL pin,
internally they would be interpreted as 32-bit ints and treated
accordingly.
(And bitslice would output 32 floats with values of 0 or 1) [1]

[1] In Sinclair basic, on the Z80, "True" was 0xFF and "False" was
0x00. That seems like a better scheme, more resilient to single-bit
flips by cosmic rays.

-- 
atp
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