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use tip5::Digest;
use triton_vm::prelude::*;
use crate::prelude::*;
/// Compare two digests
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub struct LtDigest;
impl BasicSnippet for LtDigest {
fn parameters(&self) -> Vec<(DataType, String)> {
vec![
(DataType::VoidPointer, "*digest_lhs".to_owned()),
(DataType::VoidPointer, "*digest_rhs".to_owned()),
]
}
fn return_values(&self) -> Vec<(DataType, String)> {
vec![(DataType::Bool, "digest_lhs > digest_rhs".to_owned())]
}
fn entrypoint(&self) -> String {
"tasmlib_hashing_lt_digest".to_owned()
}
fn code(&self, _library: &mut Library) -> Vec<LabelledInstruction> {
let entrypoint = self.entrypoint();
let loop_label = format!("{entrypoint}_short_circuiting_loop");
// result ∈ {0, 1} : {0: !(lhs > rhs), 1: lhs > rhs}
let compare_bfes_loop = triton_asm!(
// Invariant: _ result (*lhs - 1) *lhs[i] *rhs[i] g0 g1
{loop_label}:
hint result: bool = stack[5]
hint lhs_end_condition: BFieldElement = stack[4]
hint lhs_i_ptr = stack[3]
hint rhs_i_ptr = stack[2]
/* Check if we are done */
dup 4
dup 4
eq
skiz return
pop 2
// _ result (*lhs - 1) *lhs[i] *rhs[i]
read_mem 1
// _ result (*lhs - 1) *lhs[i] rhs[i] *rhs[i-1]
swap 2
read_mem 1
// _ result (*lhs - 1) *rhs[i-1] rhs[i] lhs[i] *lhs[i-1]
swap 3
swap 2
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] lhs[i] rhs[i]
dup 1 dup 1
eq
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] lhs[i] rhs[i] (lhs[i] == rhs[i])
skiz recurse
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] lhs[i] rhs[i]
split
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] lhs[i] rhs[i]_hi rhs[i]_lo
swap 2
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] rhs[i]_lo rhs[i]_hi lhs[i]
split
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] rhs[i]_lo rhs[i]_hi lhs[i]_hi lhs[i]_lo
/* Calculate rhs[i]_hi < lhs[i]_hi || rhs[i]_hi == rhs[i]_hi && rhs[i]_lo < lhs[i]_lo*/
dup 1 dup 3 lt
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] rhs[i]_lo rhs[i]_hi lhs[i]_hi lhs[i]_lo (lhs[i]_hi > rhs[i]_hi)
swap 4
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] (lhs[i]_hi > rhs[i]_hi) rhs[i]_hi lhs[i]_hi lhs[i]_lo rhs[i]_lo
lt
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] (lhs[i]_hi > rhs[i]_hi) rhs[i]_hi lhs[i]_hi (lhs[i]_lo > rhs[i]_lo)
swap 2 eq
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] (lhs[i]_hi > rhs[i]_hi) (lhs[i]_lo > rhs[i]_lo) (lhs[i]_hi == rhs[i]_hi)
mul
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] (lhs[i]_hi > rhs[i]_hi) ((lhs[i]_lo > rhs[i]_lo) && (lhs[i]_hi == rhs[i]_hi))
add
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] (lhs[i]_hi > rhs[i]_hi) || ((lhs[i]_lo > rhs[i]_lo) && (lhs[i]_hi == rhs[i]_hi))
// _ result (*lhs - 1) *lhs[i-1] *rhs[i-1] result'
swap 4
push 0
// _ result' (*lhs - 1) *lhs[i-1] *rhs[i-1] g0 g1
return
);
triton_asm!(
// BEFORE: _ *lhs *rhs
// AFTER: _ (lhs > rhs)
{entrypoint}:
// _ *lhs *rhs
// goal: _ result (*lhs - 1) *lhs[i] *rhs[i] g0 g1
push 0
swap 2
// _ 0 *rhs *lhs
push {Digest::LEN - 1} add
// _ 0 *rhs *lhs[4]
dup 0 push {-(Digest::LEN as isize)} add
// _ 0 *rhs *lhs[4] (*lhs - 1)
swap 2
// _ 0 (*lhs - 1) *lhs[4] *rhs
push {Digest::LEN - 1} add
// _ 0 (*lhs - 1) *lhs[4] *rhs[4]
push 0
push 0
// _ 0 (*lhs - 1) *lhs[4] *rhs[4] 0 0
// _ result (*lhs - 1) *lhs[4] *rhs[4] g0 g1
call {loop_label}
// _ result (*lhs - 1) *lhs[i] *rhs[i] g0 g1
pop 5
// _ result
return
{&compare_bfes_loop}
)
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::memory::encode_to_memory;
use crate::test_prelude::*;
impl LtDigest {
fn prepare_state(
&self,
lhs_ptr: BFieldElement,
rhs_ptr: BFieldElement,
lhs: Digest,
rhs: Digest,
) -> FunctionInitialState {
let mut memory = HashMap::default();
encode_to_memory(&mut memory, lhs_ptr, &lhs);
encode_to_memory(&mut memory, rhs_ptr, &rhs);
let stack = [self.init_stack_for_isolated_run(), vec![lhs_ptr, rhs_ptr]].concat();
FunctionInitialState { stack, memory }
}
}
impl Function for LtDigest {
fn rust_shadow(
&self,
stack: &mut Vec<BFieldElement>,
memory: &mut HashMap<BFieldElement, BFieldElement>,
) {
let load_digest = |ptr: BFieldElement| {
Digest::new([
memory[&ptr],
memory[&(ptr + bfe!(1))],
memory[&(ptr + bfe!(2))],
memory[&(ptr + bfe!(3))],
memory[&(ptr + bfe!(4))],
])
};
let rhs_ptr = stack.pop().unwrap();
let lhs_ptr = stack.pop().unwrap();
let rhs = load_digest(rhs_ptr);
let lhs = load_digest(lhs_ptr);
stack.push(bfe!((rhs < lhs) as u64));
}
fn pseudorandom_initial_state(
&self,
seed: [u8; 32],
bench_case: Option<BenchmarkCase>,
) -> FunctionInitialState {
let mut rng = StdRng::from_seed(seed);
let a_digest = Digest::new([bfe!(1), bfe!(2), bfe!(3), bfe!(4), bfe!(5)]);
let another_digest = Digest::new([bfe!(6), bfe!(7), bfe!(8), bfe!(9), bfe!(10)]);
let (lhs, rhs) = match bench_case {
Some(BenchmarkCase::CommonCase) => (a_digest, another_digest),
Some(BenchmarkCase::WorstCase) => (a_digest, a_digest),
None => (rng.random(), rng.random()),
};
let rhs_ptr: BFieldElement = rng.random();
let lhs_ptr: BFieldElement = rng.random();
self.prepare_state(lhs_ptr, rhs_ptr, lhs, rhs)
}
fn corner_case_initial_states(&self) -> Vec<FunctionInitialState> {
let lhs_ptr = bfe!(0);
let rhs_ptr = bfe!(5);
let a_digest = Digest::new([bfe!(1), bfe!(2), bfe!(3), bfe!(4), bfe!(5)]);
let another_digest = Digest::new([bfe!(6), bfe!(7), bfe!(8), bfe!(9), bfe!(10)]);
let digests_on_lowest_addresses =
self.prepare_state(lhs_ptr, rhs_ptr, a_digest, another_digest);
let same_digest_values = self.prepare_state(lhs_ptr, rhs_ptr, a_digest, a_digest);
let mut adjacent_digest_pairs = vec![];
let mut rng = rand::rng();
for i in 0..Digest::LEN {
let a: Digest = rng.random();
let mut b: Digest = a;
// `lhs == rhs`
adjacent_digest_pairs.push(self.prepare_state(lhs_ptr, rhs_ptr, a, a));
adjacent_digest_pairs.push(self.prepare_state(lhs_ptr, rhs_ptr, b, b));
// `b` "bigger" than `a` by $2^i$ at index i
// (b might be smaller than a due to wrap-around)
for j in 0..64 {
b = a;
b.0[i] += bfe!(1u64 << j);
adjacent_digest_pairs.push(self.prepare_state(lhs_ptr, rhs_ptr, a, b));
adjacent_digest_pairs.push(self.prepare_state(lhs_ptr, rhs_ptr, b, a));
}
}
[
vec![digests_on_lowest_addresses, same_digest_values],
adjacent_digest_pairs,
]
.concat()
}
}
#[test]
fn rust_shadow() {
ShadowedFunction::new(LtDigest).test()
}
}
#[cfg(test)]
mod benches {
use super::*;
use crate::test_prelude::*;
#[test]
fn lt_digest_bench() {
ShadowedFunction::new(LtDigest).bench()
}
}