Rounding up division (#10)

libraries/math/src/pool_math.sw

@@ -92,9 +92,9 @@ pub fn get_amount_in(
             xy,
             reserve_in_adjusted,
         ) - reserve_in_adjusted;
-        y * pow_decimals_in / ONE_E_18
+        rounding_up_division(y * pow_decimals_in, ONE_E_18)
     } else {
-        output_amount * reserve_in / (reserve_out - output_amount) + 1
+        rounding_up_division(output_amount * reserve_in, (reserve_out - output_amount))
     }
 }
 
@@ -291,23 +291,15 @@ fn get_y(x_0: u256, xy: u256, y: u256) -> u256 {
 
 fn calculate_fee_to_subtract(amount: u64, feeBP: u64) -> u64 {
     let nominator = amount.as_u256() * feeBP.as_u256();
-    let fee = u64::try_from(nominator / BASIS_POINTS_DENOMINATOR).unwrap();
-    if nominator % BASIS_POINTS_DENOMINATOR != 0 {
-        fee + 1
-    } else {
-        fee
-    }
+    let fee = rounding_up_division(nominator, BASIS_POINTS_DENOMINATOR);
+    u64::try_from(fee).unwrap()
 }
 
 fn calculate_fee_to_add(amount: u64, feeBP: u64) -> u64 {
     let nominator = amount.as_u256() * feeBP.as_u256();
     let denominator = BASIS_POINTS_DENOMINATOR - feeBP.as_u256();
-    let fee = u64::try_from(nominator / denominator).unwrap();
-    if nominator % denominator != 0 {
-        fee + 1
-    } else {
-        fee
-    }
+    let fee = rounding_up_division(nominator, denominator);
+    u64::try_from(fee).unwrap()
 }
 
 fn subtract_fee(amount: u64, fee: u64) -> u64 {
@@ -318,6 +310,15 @@ fn add_fee(amount: u64, fee: u64) -> u64 {
     amount + calculate_fee_to_add(amount, fee)
 }
 
+fn rounding_up_division(nominator: u256, denominator: u256) -> u256 {
+    let rounding_down_division_result = nominator / denominator;
+    if nominator % denominator == 0 {
+        rounding_down_division_result
+    } else {
+        rounding_down_division_result + 1
+    }
+}
+
 // Tests
 #[test]
 fn test_pow_decimals() {
@@ -379,3 +380,23 @@ fn test_calculate_fee_to_add() {
         i = i + 1;
     }
 }
+
+#[test]
+fn test_rounding_up_division() {
+    assert_eq(rounding_up_division(1000, 1000), 1);
+    assert_eq(rounding_up_division(1000, 1), 1000);
+    assert_eq(rounding_up_division(1000, 5), 200);
+    assert_eq(rounding_up_division(1000, 2000), 1);
+    assert_eq(rounding_up_division(9, 3), 3);
+    assert_eq(rounding_up_division(10, 3), 4);
+    assert_eq(rounding_up_division(11, 3), 4);
+    assert_eq(rounding_up_division(12, 3), 4);
+    assert_eq(
+        rounding_up_division(pow_decimals(72), pow_decimals(12)),
+        pow_decimals(60),
+    );
+    assert_eq(
+        rounding_up_division(pow_decimals(72) + 1, pow_decimals(12)),
+        pow_decimals(60) + 1,
+    );
+}