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Implement signextend in interpreter

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Robin Salen 2023-04-06 17:11:44 -04:00
parent 4db004417c
commit b943ddb0d2
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GPG Key ID: F98FD38F65687358
1 changed files with 26 additions and 1 deletions
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27
evm/src/cpu/kernel/interpreter.rs
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@ -312,7 +312,7 @@ impl<'a> Interpreter<'a> {
0x08 => self.run_addmod(), // "ADDMOD",
0x09 => self.run_mulmod(), // "MULMOD",
0x0a => self.run_exp(), // "EXP",
0x0b => todo!(), // "SIGNEXTEND",
0x0b => self.run_signextend(), // "SIGNEXTEND",
0x0c => self.run_addfp254(), // "ADDFP254",
0x0d => self.run_mulfp254(), // "MULFP254",
0x0e => self.run_subfp254(), // "SUBFP254",
@ -589,6 +589,31 @@ impl<'a> Interpreter<'a> {
self.push_bool(signed_cmp(x, y) == Ordering::Greater);
}
fn run_signextend(&mut self) {
let n = self.pop();
let x = self.pop();
if n > U256::from(31) {
self.push(x);
} else {
let n = n.low_u64() as usize;
let num_bytes_prepend = 31 - n;
let mut x_bytes = [0u8; 32];
x.to_big_endian(&mut x_bytes);
let mut x_bytes = x_bytes[num_bytes_prepend..].to_vec();
let sign_bit = x_bytes[0] >> 7;
self.push(if sign_bit == 0 {
x_bytes.extend_from_slice(&vec![0; num_bytes_prepend]);
U256::from_big_endian(&x_bytes)
} else {
let mut tmp = vec![0xff; num_bytes_prepend];
tmp.extend_from_slice(&x_bytes);
U256::from_big_endian(&tmp)
});
}
}
fn run_eq(&mut self) {
let x = self.pop();
let y = self.pop();