ark_ff_macros/montgomery/
biginteger.rs

1use quote::quote;
2
3pub(super) fn add_with_carry_impl(num_limbs: usize) -> proc_macro2::TokenStream {
4    let mut body = proc_macro2::TokenStream::new();
5    body.extend(quote! {
6        use ark_ff::biginteger::arithmetic::adc_for_add_with_carry as adc;
7        let mut carry = 0;
8    });
9    for i in 0..num_limbs {
10        body.extend(quote! {
11            carry = adc(&mut a.0[#i], b.0[#i], carry);
12        });
13    }
14    body.extend(quote! {
15        carry != 0
16    });
17    quote! {
18        #[inline(always)]
19        fn __add_with_carry(
20            a: &mut B,
21            b: & B,
22        ) -> bool {
23            #body
24        }
25    }
26}
27
28pub(super) fn sub_with_borrow_impl(num_limbs: usize) -> proc_macro2::TokenStream {
29    let mut body = proc_macro2::TokenStream::new();
30    body.extend(quote! {
31        use ark_ff::biginteger::arithmetic::sbb_for_sub_with_borrow as sbb;
32        let mut borrow = 0;
33    });
34    for i in 0..num_limbs {
35        body.extend(quote! {
36            borrow = sbb(&mut a.0[#i], b.0[#i], borrow);
37        });
38    }
39    body.extend(quote! {
40        borrow != 0
41    });
42    quote! {
43        #[inline(always)]
44        fn __sub_with_borrow(
45            a: &mut B,
46            b: & B,
47        ) -> bool {
48            #body
49        }
50    }
51}
52
53pub(super) fn subtract_modulus_impl(
54    modulus: &proc_macro2::TokenStream,
55) -> proc_macro2::TokenStream {
56    quote! {
57        #[inline(always)]
58        fn __subtract_modulus(a: &mut F) {
59            if a.is_geq_modulus() {
60                __sub_with_borrow(&mut a.0, &#modulus);
61            }
62        }
63
64        #[inline(always)]
65        fn __subtract_modulus_with_carry(a: &mut F, carry: bool) {
66            if a.is_geq_modulus() || carry {
67                __sub_with_borrow(&mut a.0, &#modulus);
68            }
69        }
70    }
71}
ark_ff_macros/montgomery/biginteger.rs

ark_ff_macros/montgomery/
biginteger.rs
