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// generated source. do not edit.
#![allow(non_upper_case_globals, unused_macros, unused_imports)]
use crate::low::macros::*;
// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT-0
// ----------------------------------------------------------------------------
// Reduce modulo group order, z := x mod n_521
// Input x[9]; output z[9]
//
// extern void bignum_mod_n521_9(uint64_t z[static 9], const uint64_t x[static 9]);
//
// Reduction is modulo the group order of the NIST curve P-521.
//
// Standard ARM ABI: X0 = z, X1 = x
// ----------------------------------------------------------------------------
macro_rules! z {
() => {
"x0"
};
}
macro_rules! x {
() => {
"x1"
};
}
macro_rules! n0 {
() => {
"x2"
};
}
macro_rules! n1 {
() => {
"x3"
};
}
macro_rules! n2 {
() => {
"x4"
};
}
macro_rules! n3 {
() => {
"x5"
};
}
macro_rules! d0 {
() => {
"x6"
};
}
macro_rules! d1 {
() => {
"x7"
};
}
macro_rules! d2 {
() => {
"x8"
};
}
macro_rules! d3 {
() => {
"x9"
};
}
macro_rules! d4 {
() => {
"x10"
};
}
macro_rules! d5 {
() => {
"x11"
};
}
macro_rules! d6 {
() => {
"x12"
};
}
macro_rules! d7 {
() => {
"x13"
};
}
macro_rules! d8 {
() => {
"x14"
};
}
macro_rules! q {
() => {
"x15"
};
}
// Re-use d6 and d7 as temporaries before they are needed
macro_rules! s {
() => {
Q!(d6!())
};
}
macro_rules! t {
() => {
Q!(d7!())
};
}
macro_rules! movbig {
($nn:expr, $n3:expr, $n2:expr, $n1:expr, $n0:expr) => { Q!(
"movz " $nn ", " $n0 ";\n"
"movk " $nn ", " $n1 ", lsl #16;\n"
"movk " $nn ", " $n2 ", lsl #32;\n"
"movk " $nn ", " $n3 ", lsl #48"
)}
}
/// Reduce modulo group order, z := x mod n_521
///
/// Input x[9]; output z[9]
///
/// Reduction is modulo the group order of the NIST curve P-521.
pub(crate) fn bignum_mod_n521(z: &mut [u64; 9], x: &[u64; 9]) {
// SAFETY: inline assembly. see [crate::low::inline_assembly_safety] for safety info.
unsafe {
core::arch::asm!(
Q!(Label!("bignum_mod_n521_9_alt", 2) ":"),
// Load the top digit first into d8.
// The initial quotient estimate is q = h + 1 where x = 2^521 * h + t
Q!(" ldr " d8!() ", [" x!() ", #64]"),
Q!(" lsr " q!() ", " d8!() ", #9"),
Q!(" add " q!() ", " q!() ", #1"),
// Let [5; n3; n2; n1; n0] = r_521 = 2^521 - n_521
// and form [d4;d3;d2;d1;d0] = q * r_521
movbig!(n0!(), "#0x4490", "#0x48e1", "#0x6ec7", "#0x9bf7"),
Q!(" mul " d0!() ", " n0!() ", " q!()),
movbig!(n1!(), "#0xc44a", "#0x3647", "#0x7663", "#0xb851"),
Q!(" mul " d1!() ", " n1!() ", " q!()),
movbig!(n2!(), "#0x8033", "#0xfeb7", "#0x08f6", "#0x5a2f"),
Q!(" mul " d2!() ", " n2!() ", " q!()),
movbig!(n3!(), "#0xae79", "#0x787c", "#0x40d0", "#0x6994"),
Q!(" mul " d3!() ", " n3!() ", " q!()),
Q!(" lsl " d4!() ", " q!() ", #2"),
Q!(" add " d4!() ", " d4!() ", " q!()),
Q!(" umulh " t!() ", " n0!() ", " q!()),
Q!(" adds " d1!() ", " d1!() ", " t!()),
Q!(" umulh " t!() ", " n1!() ", " q!()),
Q!(" adcs " d2!() ", " d2!() ", " t!()),
Q!(" umulh " t!() ", " n2!() ", " q!()),
Q!(" adcs " d3!() ", " d3!() ", " t!()),
Q!(" umulh " t!() ", " n3!() ", " q!()),
Q!(" adc " d4!() ", " d4!() ", " t!()),
// Now load other digits and form r = x - q * n_521 = (q * r_521 + t) - 2^521.
// But the computed result stuffs in 1s from bit 521 onwards and actually
// gives r' = (q * r_521 + t) + (2^576 - 2^521) = r + 2^576, including the
// top carry. Hence CF <=> r >= 0, while r' == r (mod 2^521).
Q!(" ldp " s!() ", " t!() ", [" x!() "]"),
Q!(" adds " d0!() ", " d0!() ", " s!()),
Q!(" adcs " d1!() ", " d1!() ", " t!()),
Q!(" ldp " s!() ", " t!() ", [" x!() ", #16]"),
Q!(" adcs " d2!() ", " d2!() ", " s!()),
Q!(" adcs " d3!() ", " d3!() ", " t!()),
Q!(" ldp " t!() ", " d5!() ", [" x!() ", #32]"),
Q!(" adcs " d4!() ", " d4!() ", " t!()),
Q!(" adcs " d5!() ", " d5!() ", xzr"),
Q!(" ldp " d6!() ", " d7!() ", [" x!() ", #48]"),
Q!(" adcs " d6!() ", " d6!() ", xzr"),
Q!(" adcs " d7!() ", " d7!() ", xzr"),
Q!(" orr " d8!() ", " d8!() ", # ~ 0x1FF"),
Q!(" adcs " d8!() ", " d8!() ", xzr"),
// We already know r < n_521, but if it actually went negative then
// we need to add back n_521 again. Recycle q as a bitmask for r < n_521,
// and just subtract r_521 and mask rather than literally adding 2^521.
// This also gets rid of the bit-stuffing above.
Q!(" csetm " q!() ", cc"),
Q!(" and " n0!() ", " n0!() ", " q!()),
Q!(" subs " d0!() ", " d0!() ", " n0!()),
Q!(" and " n1!() ", " n1!() ", " q!()),
Q!(" sbcs " d1!() ", " d1!() ", " n1!()),
Q!(" and " n2!() ", " n2!() ", " q!()),
Q!(" sbcs " d2!() ", " d2!() ", " n2!()),
Q!(" and " n3!() ", " n3!() ", " q!()),
Q!(" sbcs " d3!() ", " d3!() ", " n3!()),
Q!(" mov " n0!() ", #5"),
Q!(" and " n0!() ", " n0!() ", " q!()),
Q!(" sbcs " d4!() ", " d4!() ", " n0!()),
Q!(" sbcs " d5!() ", " d5!() ", xzr"),
Q!(" sbcs " d6!() ", " d6!() ", xzr"),
Q!(" sbcs " d7!() ", " d7!() ", xzr"),
Q!(" sbc " d8!() ", " d8!() ", xzr"),
Q!(" and " d8!() ", " d8!() ", #0x1FF"),
// Store the end result
Q!(" stp " d0!() ", " d1!() ", [" z!() "]"),
Q!(" stp " d2!() ", " d3!() ", [" z!() ", #16]"),
Q!(" stp " d4!() ", " d5!() ", [" z!() ", #32]"),
Q!(" stp " d6!() ", " d7!() ", [" z!() ", #48]"),
Q!(" str " d8!() ", [" z!() ", #64]"),
inout("x0") z.as_mut_ptr() => _,
inout("x1") x.as_ptr() => _,
// clobbers
out("x10") _,
out("x11") _,
out("x12") _,
out("x13") _,
out("x14") _,
out("x15") _,
out("x2") _,
out("x3") _,
out("x4") _,
out("x5") _,
out("x6") _,
out("x7") _,
out("x8") _,
out("x9") _,
)
};
}