Merge branch 'main' of git.cplus.link:cetus/cetus-amm into main

# Conflicts:
#	sources/amm_math.move

sources/amm_math.move

@@ -1,12 +1,38 @@
 module cetus_amm::amm_math {
+    use cetus_amm::u256::{Self, U256};
     use std::error;
 
-    const ERROR_ROUTER_PARAMETER_INVALID: u64 = 1001;
+    //
+    // Errors
+    //
+    const EMATH_DIVIDE_BY_ZERO: u64 = 2001;
+    const ERROR_ROUTER_PARAMETER_INVALID: u64 = 2001;
+
+    public fun safe_compare_mul_u128(a1: u128, b1: u128, a2: u128, b2: u128): u8 {
+        let left = u256::mul(u256::from_u128(a1), u256::from_u128(b1));
+        let right = u256::mul(u256::from_u128(a2), u256::from_u128(b2));
+        u256::compare(left, right)
+    }
+
+    public fun safe_mul_div_u128(x: u128, y: u128, z: u128): u128 {
+        u256::as_u128(mul_div_u128(x, y, z))
+    }
+
+    public fun mul_div_u128(x: u128, y: u128, z: u128): U256 {
+        if (z == 0) {
+            abort error::invalid_argument(EMATH_DIVIDE_BY_ZERO)
+        };
+
+        let x_u256 = u256::from_u128(x);
+        let y_u256 = u256::from_u128(y);
+        let z_u256 = u256::from_u128(z);
+        u256::div(u256::mul(x_u256, y_u256), z_u256)
+    }
 
     public fun quote(amount_a: u128, reserve_a: u128, reserve_b: u128): u128 {
         assert!(amount_a > 0, error::invalid_argument(ERROR_ROUTER_PARAMETER_INVALID));
         assert!(reserve_a > 0 && reserve_b> 0, error::invalid_argument(ERROR_ROUTER_PARAMETER_INVALID));
-        let amount_y = amount_a * reserve_b / reserve_a;
+        let amount_y = safe_mul_div_u128(amount_a,reserve_b,reserve_a);
         amount_y
     }
 
@@ -24,6 +50,6 @@ module cetus_amm::amm_math {
     }
 
     public fun min(x: u128, y: u128): u128 {
-        if (x < y) x else y
+        if (x < y) x else y 
     }
 }