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use std::collections::HashMap;
use triton_vm::prelude::*;
use crate::prelude::*;
use crate::traits::basic_snippet::Reviewer;
use crate::traits::basic_snippet::SignOffFingerprint;
/// Multiply two `u64`s and crash on overflow.
///
/// ### Behavior
///
/// ```text
/// BEFORE: _ [right: u64] [left: u64]
/// AFTER: _ [right · left: u64]
/// ```
///
/// ### Preconditions
///
/// - all input arguments are properly [`BFieldCodec`] encoded
/// - the product of `left` and `right` is less than or equal to [`u64::MAX`]
///
/// ### Postconditions
///
/// - the output is the product of the input
/// - the output is properly [`BFieldCodec`] encoded
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub struct SafeMul;
impl BasicSnippet for SafeMul {
fn parameters(&self) -> Vec<(DataType, String)> {
["rhs", "lhs"]
.map(|side| (DataType::U64, side.to_string()))
.to_vec()
}
fn return_values(&self) -> Vec<(DataType, String)> {
vec![(DataType::U64, "product".to_string())]
}
fn entrypoint(&self) -> String {
"tasmlib_arithmetic_u64_safe_mul".to_string()
}
fn code(&self, _: &mut Library) -> Vec<LabelledInstruction> {
triton_asm!(
// BEFORE: _ right_hi right_lo left_hi left_lo
// AFTER: _ prod_hi prod_lo
{self.entrypoint()}:
/* left_lo · right_lo */
dup 0
dup 3
mul
// _ right_hi right_lo left_hi left_lo (left_lo · right_lo)
/* left_lo · right_hi (consume left_lo) */
dup 4
pick 2
mul
// _ right_hi right_lo left_hi (left_lo · right_lo) (left_lo · right_hi)
/* left_hi · right_lo (consume right_lo) */
pick 3
dup 3
mul
// _ right_hi left_hi (left_lo · right_lo) (left_lo · right_hi) (left_hi · right_lo)
/* left_hi · right_hi (consume left_hi and right_hi) */
pick 4
pick 4
mul
// _ (left_lo · right_lo) (left_lo · right_hi) (left_hi · right_lo) (left_hi · right_hi)
/* assert left_hi · right_hi == 0 */
push 0
eq
assert error_id 100
// _ (left_lo · right_lo) (left_lo · right_hi) (left_hi · right_lo)
// _ lolo lohi hilo
/* prod_hi = lolo_hi + lohi_lo + hilo_lo */
split
pick 1
push 0
eq
assert error_id 101
// _ lolo lohi hilo_lo
pick 1
split
pick 1
push 0
eq
assert error_id 102
// _ lolo hilo_lo lohi_lo
pick 2
split
// _ hilo_lo lohi_lo lolo_hi lolo_lo
// _ hilo_lo lohi_lo lolo_hi prod_lo
place 3
add
add
// _ prod_lo (hilo_lo + lohi_lo + lolo_hi)
split
pick 1
push 0
eq
assert error_id 103
// _ prod_lo (hilo_lo + lohi_lo + lolo_hi)_lo
// _ prod_lo prod_hi
place 1
return
)
}
fn sign_offs(&self) -> HashMap<Reviewer, SignOffFingerprint> {
let mut sign_offs = HashMap::new();
sign_offs.insert(Reviewer("ferdinand"), 0xe472ad0d428ed30c.into());
sign_offs
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::test_prelude::*;
impl Closure for SafeMul {
type Args = (u64, u64);
fn rust_shadow(&self, stack: &mut Vec<BFieldElement>) {
let (right, left) = pop_encodable::<Self::Args>(stack);
let (product, is_overflow) = left.overflowing_mul(right);
assert!(!is_overflow);
push_encodable(stack, &product);
}
fn pseudorandom_args(
&self,
seed: [u8; 32],
bench_case: Option<BenchmarkCase>,
) -> Self::Args {
let Some(bench_case) = bench_case else {
let mut rng = StdRng::from_seed(seed);
return (rng.next_u32().into(), rng.next_u32().into());
};
match bench_case {
BenchmarkCase::CommonCase => (1 << 31, (1 << 25) - 1),
BenchmarkCase::WorstCase => (1 << 31, (1 << 31) - 1),
}
}
}
#[test]
fn rust_shadow() {
ShadowedClosure::new(SafeMul).test();
}
#[test]
fn overflow_tests() {
let failure_conditions = [
(1 << 32, 1 << 32, 100), // (left_hi · right_hi) != 0
(1 << 31, 1 << 33, 101), // (left_lo · right_hi)_hi != 0
(1 << 33, 1 << 31, 102), // (left_hi · right_lo)_hi != 0
((1 << 31) - 1, (1 << 33) + 5, 103), // (hilo_lo + lohi_lo + lolo_hi)_hi != 0
];
for (left, right, error_id) in failure_conditions {
let safe_mul = ShadowedClosure::new(SafeMul);
let stack = SafeMul.set_up_test_stack((left, right));
let vm_state = InitVmState::with_stack(stack);
test_assertion_failure(&safe_mul, vm_state, &[error_id]);
}
}
}
#[cfg(test)]
mod benches {
use super::*;
use crate::test_prelude::*;
#[test]
fn benchmark() {
ShadowedClosure::new(SafeMul).bench();
}
}