Domains

src/common/consts.cairo

@@ -1,5 +1,7 @@
 const STARK_PRIME: u256 =
     3618502788666131213697322783095070105623107215331596699973092056135872020481;
+const STARK_PRIME_MINUS_ONE: felt252 =
+    3618502788666131213697322783095070105623107215331596699973092056135872020480;
 const STARK_PRIME_MINUS_TWO: felt252 =
     3618502788666131213697322783095070105623107215331596699973092056135872020479;
 

src/domains.cairo

@@ -0,0 +1,47 @@
+use core::traits::Div;
+use cairo_verifier::{
+    common::{consts::{FIELD_GENERATOR, STARK_PRIME_MINUS_ONE}, math::{pow, mul_inverse}},
+    stark::StarkConfig,
+};
+
+// Information about the domains that are used in the stark proof.
+#[derive(Drop, Copy)]
+struct StarkDomains {
+    // Log2 of the evaluation domain size.
+    log_eval_domain_size: felt252,
+    // The evaluation domain size.
+    eval_domain_size: felt252,
+    // The generator of the evaluation domain (a primitive root of unity of order eval_domain_size).
+    eval_generator: felt252,
+    // Log2 of the trace domain size.
+    log_trace_domain_size: felt252,
+    // The trace domain size.
+    trace_domain_size: felt252,
+    // The generator of the trace domain (a primitive root of unity of order trace_domain_size).
+    trace_generator: felt252,
+}
+
+#[generate_trait]
+impl StarkDomainsImpl of StarkDomainsTrait {
+    fn new(stark_config: @StarkConfig) -> StarkDomains {
+        // Compute stark_domains.
+        let log_eval_domain_size = *stark_config.log_trace_domain_size + *stark_config.log_n_cosets;
+        let eval_domain_size = pow(2, log_eval_domain_size);
+        let eval_generator = pow(
+            FIELD_GENERATOR, STARK_PRIME_MINUS_ONE * mul_inverse(eval_domain_size)
+        );
+        let trace_domain_size = pow(2, *stark_config.log_trace_domain_size);
+        let trace_generator = pow(
+            FIELD_GENERATOR, STARK_PRIME_MINUS_ONE * mul_inverse(trace_domain_size)
+        );
+
+        StarkDomains {
+            log_eval_domain_size,
+            eval_domain_size,
+            eval_generator,
+            log_trace_domain_size: *stark_config.log_trace_domain_size,
+            trace_domain_size,
+            trace_generator,
+        }
+    }
+}

src/lib.cairo

@@ -2,6 +2,7 @@ mod air;
 mod channel;
 mod common;
 mod deserialization;
+mod domains;
 mod fri;
 mod oods;
 mod proof_of_work;

src/stark.cairo

@@ -4,6 +4,7 @@ use cairo_verifier::{
         traces::{TracesUnsentCommitment, TracesDecommitment, TracesWitness}
     },
     fri::{fri_config::{FriConfig, FriConfigTrait}, fri::{FriUnsentCommitment, FriWitness}},
+    domains::StarkDomainsImpl,
     table_commitment::{TableCommitmentConfig, TableCommitmentWitness, TableDecommitment},
     proof_of_work::{
         config::{ProofOfWorkConfig, ProofOfWorkConfigTrait},
@@ -33,10 +34,10 @@ struct StarkProof {
 impl StarkProofImpl of StarkProofTrait {
     fn verify(self: @StarkProof) {
         self.config.validate(SECURITY_BITS);
+        let stark_domains = StarkDomainsImpl::new(self.config);
     }
 }
 
-
 #[derive(Drop, Copy)]
 struct StarkConfig {
     traces: TracesConfig,