feat: add small signed integers #49
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| #define OCAML_INTEGERS_INTERNAL 1 | ||
| #include "ocaml_integers.h" | ||
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| CAMLprim value integers_int_size(value unit) |
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Sys.int_size was added in 4.03, so I copied this small function from the compiler distribution.
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I'd prefer to update the minimum requirement to OCaml 4.03 and call the function from the distribution
| base = 8; pos += 2; break; \ | ||
| case 'b': case 'B': \ | ||
| base = 2; pos += 2; break; \ | ||
| case 'u': case 'U': /* Unsigned prefix. No-op for unsigned types */ \ |
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I left this comment in place because I'm still not 100% sure what the behavior here should be after reading the comments in Stdlib.int_of_string -- I think it's possible this case is already taken care of here since we're parsing directly into an integer of correct size rather than an intnat?
| let shift_left : t -> int -> t = fun x y -> fix (x lsl y) | ||
| let shift_right : t -> int -> t = ( asr ) | ||
| let shift_right_logical : t -> int -> t = fun x y -> | ||
| ((x lsl (int_size - bits)) lsr y) asr (int_size - bits) |
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This is done to handle the case of preservation when the RHS is 0 -- it's a bit ugly so if there's a better way to do it I'm all ears.
| let of_string = of_string | ||
| let to_string = to_string | ||
| let to_hexstring = to_hexstring |
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| let of_string = of_string | |
| let to_string = to_string | |
| let to_hexstring = to_hexstring | |
| let of_string = S.of_string | |
| let to_string = S.to_string | |
| let to_hexstring = S.to_hexstring |
(for consistency with min_int and max_int above).
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| module MakeSmall(S : Small) = | ||
| struct | ||
| open S |
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| open S |
(see suggestion to use qualified names below)
| return caml_copy_string(buf); \ | ||
| } \ | ||
| \ | ||
| /* to_hexstring : t -> string */ \ |
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The specification of to_hexstring (which should really be more clearly documented in the existing code) is
hex pretty-printing (to mimic "%x")
(see #33 (comment)).
which means, e.g.:
# Printf.sprintf "%x" (-15);;
- : string = "7ffffffffffffff1"
| @@ -0,0 +1,81 @@ | |||
| let () = print_endline "Small int operations test: ?" | |||
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It'd be good to have some tests for parsing and printing
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Any word on getting this merged and published? It would be really handy! Edit: Created a PR addressing the review comments at #51 |
This PR adds 8 and 16 bit signed integer support. I attempted to mirror as much of the existing code as possible, but there still might be room for improvement -- it's been awhile since I've written much C.
I'll add some comments on the code itself to explain some of the rationale/outstanding questions.