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Implement smod in interpreter

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Robin Salen 2023-04-06 16:46:10 -04:00
parent 18d317b9cf
commit 232832e34d
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GPG Key ID: FB87BACFB3CB2007
1 changed files with 29 additions and 1 deletions
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30
evm/src/cpu/kernel/interpreter.rs
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@ -308,7 +308,7 @@ impl<'a> Interpreter<'a> {
0x04 => self.run_div(), // "DIV",
0x05 => self.run_sdiv(), // "SDIV",
0x06 => self.run_mod(), // "MOD",
0x07 => todo!(), // "SMOD",
0x07 => self.run_smod(), // "SMOD",
0x08 => self.run_addmod(), // "ADDMOD",
0x09 => self.run_mulmod(), // "MULMOD",
0x0a => self.run_exp(), // "EXP",
@ -509,6 +509,34 @@ impl<'a> Interpreter<'a> {
self.push(if y.is_zero() { U256::zero() } else { x % y });
}
fn run_smod(&mut self) {
let mut x = self.pop();
let mut y = self.pop();
if y.is_zero() {
self.push(U256::zero());
} else {
let x_is_pos = x.eq(&(x & SIGN_MASK));
let y_is_pos = y.eq(&(y & SIGN_MASK));
// We compute the absolute remainder first,
// then adapt its sign based on the operands.
if !x_is_pos {
x = two_complement(x);
}
if !y_is_pos {
y = two_complement(y);
}
let rem = x % y;
if rem.eq(&U256::zero()) {
self.push(U256::zero());
}
// Remainder always has the same sign as the dividend.
self.push(if x_is_pos { rem } else { two_complement(rem) });
}
}
fn run_addmod(&mut self) {
let x = U512::from(self.pop());
let y = U512::from(self.pop());