[revm] gas refactor

crates/revm/src/gas.rs

@@ -1,6 +1,5 @@
 mod calc;
 mod constants;
-mod utils;
 
 pub use calc::*;
 pub use constants::*;

crates/revm/src/gas/calc.rs

@@ -63,6 +63,26 @@ pub fn create2_cost(len: usize) -> Option<u64> {
     Some(gas)
 }
 
+
+fn log2floor(value: U256) -> u64 {
+    assert!(!value.is_zero());
+    let mut l: u64 = 256;
+    for i in 0..4 {
+        let i = 3 - i;
+        if value.0[i] == 0u64 {
+            l -= 64;
+        } else {
+            l -= value.0[i].leading_zeros() as u64;
+            if l == 0 {
+                return l;
+            } else {
+                return l - 1;
+            }
+        }
+    }
+    l
+}
+
 pub fn exp_cost<SPEC: Spec>(power: U256) -> Option<u64> {
     if power.is_zero() {
         Some(EXP)
@@ -73,7 +93,7 @@ pub fn exp_cost<SPEC: Spec>(power: U256) -> Option<u64> {
             10
         }); // EIP-160: EXP cost increase
         let gas = U256::from(EXP).checked_add(
-            gas_byte.checked_mul(U256::from(super::utils::log2floor(power) / 8 + 1))?,
+            gas_byte.checked_mul(U256::from(log2floor(power) / 8 + 1))?,
         )?;
 
         if gas > U256::from(u64::MAX) {

crates/revm/src/interpreter/memory.rs

@@ -131,16 +131,5 @@ mod tests {
             let next_multiple = x + 32 - (x % 32);
             assert_eq!(Some(next_multiple), next_multiple_of_32(x.into()));
         }
-
-        // // next_multiple_of_32 returns None when the next multiple of 32 is too big
-        // let last_multiple_of_32 = U256::MAX & !U256::from(31);
-        // for i in 0..63 {
-        //     let x = U256::MAX - U256::from(i);
-        //     if x > last_multiple_of_32 {
-        //         assert_eq!(None, next_multiple_of_32(x));
-        //     } else {
-        //         assert_eq!(Some(last_multiple_of_32), next_multiple_of_32(x));
-        //     }
-        // }
     }
 }