floor div, variadic mod

[primo-ppcg]

Related issue: #1206

• Adds floored division to corelib (div)
• Makes mod and % variadic
• Defines (mod x 0) as x, (% x 0) is unchanged

[sogaiu]

I wanted to bring up the issue of where tests related to int/*64 ought to live.

When working on the reorganization of tests recently, I made some changes in that direction, namely to place some things with int/s64 or int/u64 in suite-inttypes.janet. This was motivated by this comment having to do with (eventually?) arranging things so that we can:

run testing when certain features are disabled - for example, to be able to run make test and pass, even if FFI is disabled.

I don't think I got everything relevant moved in to suite-inttypes.janet so if this is a direction we want to go in, there are still some changes to be made.

Perhaps the comments above belong in a separate issue, but if there are to be tests in this PR that use int/*64 perhaps it would be worth thinking about where they should go. If it's not too much trouble may be they can go in suite-inttypes.janet?

[primo-ppcg]

I don't think I got everything relevant moved in to suite-inttypes.janet so if this is a direction we want to go in, there are still some changes to be made.

I'll be adding a few more tests to this suite. While I'm there, I can look into moving any remaining tests as well.

[sogaiu]

Thanks for the test moving / shielding in b3db367.

Looking over the proposed changes in 8a62c74, I was reminded of something @pyrmont mentioned recently about how int/64 and int/u64 do not provide complement / not. I didn't figure out whether there is some reason it isn't doable. Perhaps it's something that should have a separate issue.

[primo-ppcg]

I was reminded of something @pyrmont mentioned recently about how int/64 and int/u64 do not provide complement / not.

I can't immediately think of a reason why bnot shouldn't be supported by int types... although if I were to attempt to implement it, I suspect I may quickly discover the reason 😉

Firstly, the vm asserts that the type is :number rather than deferring to abstract implementations:

janet/src/core/vm.c

Lines 731 to 736 in b125cbe

	VM_OP(JOP_BNOT) {
	Janet op = stack[E];
	vm_assert_type(op, JANET_NUMBER);
	stack[A] = janet_wrap_integer(~janet_unwrap_integer(op));
	vm_pcnext();
	}

I think that's all that would need to change, apart from the implementation in inttypes, of course.

Definitely a separate PR, though.