On Sat, Feb 10, 2024 at 04:07:12PM +0200, Al wrote: > On 2024-02-10 15:38, Peter Bex wrote: > > > That's because you're using fixnum mode. As I explained, using literals > > that might be too large for fixnums break the fixnum mode's premise that > > everything must be a fixnum. > > Oh. So it refuses to emit C code that might break on 32-bit at runtime > (silent truncation of atoi result, presumably), preferring instead to > definitely break during Scheme compilation on any platform. OK, I get the > rationale.
Yup. Like I said, it might be doable to add some sort of mode where it could be used to compile in fixnum mode exclusively for 64-bit platforms, but someone would have to spend the time to do so. > > That's because string->number gets constant-folded and evaluated at > > compile-time. > > Obviously; and I suppose there's no simple way to prevent that for just one > line, not the entire unit? Not really. The foreign-value you've been using is a good hack because it performs exactly the conversion that you're looking for under the hood. It also forms an optimization barrier so the constant can't be precalculated. Note that foreign-value can still return bignums on 32-bit platforms if the value doesn't fit in a fixnum (this is done by C_unsigned_int_to_num in chicken.h) and you're using integer32. The int32 version doesn't do this and assumes it'll just fit into a fixnum. > I did mention twice that I'm using them to implement int->u32. That should only be needed if you generated values bigger than 32-bit. Again, these could still be bignums when run on a 32-bit platform (that's why the return type of s32vector-ref is defined as "integer" and not "fixnum") > There are also places where I need to increment-and-wrap int32's by > INT32_MIN. I'm > writing a Forth compiler incidentally (which may or may not have been a good > idea). I store values in s32vector's, but they get turned into Scheme > numbers by s32vector-ref. I guess I'd prefer native s32int/u32int types, > complete with wrap-around and meaningful conversion to Scheme ints, but I > don't think that exists. Unfortunately, no. Another way of accomplishing what you want is to use the fx operations directly. AFAICT those aren't constant-folded. So something like this should work: (define (->32bit x) (fxand (- (fxshl 1 32) 1) x)) Alternatively, put the conversion code (including big-fixnum literals) in a separate Scheme file which is compiled *without* fixnum mode, and call it from the file that is compiled in fixnum mode. Cheers, Peter
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