fixed incorrect usage of "underflow"

Author: aritkulova

docs/stdlib.json

@@ -340,14 +340,14 @@
     "section": "`u8` arithmetic",
     "input_type": "u8, u8",
     "output_type": "Option<u8>",
-    "description": "Subtract the second `u8` value from the first. Return `Some` of the difference, or `None` if the result would underflow `u8`."
+    "description": "Subtract the second `u8` value from the first. Return `Some` of the difference, or `None` if the result would overflow `u8`."
   },
   {
     "simplicityhl_name": "safe_sub_8",
     "section": "`u8` arithmetic",
     "input_type": "u8, u8",
     "output_type": "u8",
-    "description": "Subtract the second `u8` value from the first.\n\n## Panics\nPanics if the result would underflow `u8`."
+    "description": "Subtract the second `u8` value from the first.\n\n## Panics\nPanics if the result would overflow `u8`."
   },
   {
     "simplicityhl_name": "checked_mul_8",
@@ -466,14 +466,14 @@
     "section": "`u16` arithmetic",
     "input_type": "u16, u16",
     "output_type": "Option<u16>",
-    "description": "Subtract the second `u16` value from the first. Return `Some` of the difference, or `None` if the result would underflow `u16`."
+    "description": "Subtract the second `u16` value from the first. Return `Some` of the difference, or `None` if the result would overflow `u16`."
   },
   {
     "simplicityhl_name": "safe_sub_16",
     "section": "`u16` arithmetic",
     "input_type": "u16, u16",
     "output_type": "u16",
-    "description": "Subtract the second `u16` value from the first.\n\n## Panics\nPanics if the result would underflow `u16`."
+    "description": "Subtract the second `u16` value from the first.\n\n## Panics\nPanics if the result would overflow `u16`."
   },
   {
     "simplicityhl_name": "checked_mul_16",
@@ -592,14 +592,14 @@
     "section": "`u32` arithmetic",
     "input_type": "u32, u32",
     "output_type": "Option<u32>",
-    "description": "Subtract the second `u32` value from the first. Return `Some` of the difference, or `None` if the result would underflow `u32`."
+    "description": "Subtract the second `u32` value from the first. Return `Some` of the difference, or `None` if the result would overflow `u32`."
   },
   {
     "simplicityhl_name": "safe_sub_32",
     "section": "`u32` arithmetic",
     "input_type": "u32, u32",
     "output_type": "u32",
-    "description": "Subtract the second `u32` value from the first.\n\n## Panics\nPanics if the result would underflow `u32`."
+    "description": "Subtract the second `u32` value from the first.\n\n## Panics\nPanics if the result would overflow `u32`."
   },
   {
     "simplicityhl_name": "checked_mul_32",
@@ -725,14 +725,14 @@
     "section": "`u64` arithmetic",
     "input_type": "u64, u64",
     "output_type": "Option<u64>",
-    "description": "Subtract the second `u64` value from the first. Return `Some` of the difference, or `None` if the result would underflow `u64`."
+    "description": "Subtract the second `u64` value from the first. Return `Some` of the difference, or `None` if the result would overflow `u64`."
   },
   {
     "simplicityhl_name": "safe_sub_64",
     "section": "`u64` arithmetic",
     "input_type": "u64, u64",
     "output_type": "u64",
-    "description": "Subtract the second `u64` value from the first.\n\n## Panics\nPanics if the result would underflow `u64`."
+    "description": "Subtract the second `u64` value from the first.\n\n## Panics\nPanics if the result would overflow `u64`."
   },
   {
     "simplicityhl_name": "checked_mul_64",
@@ -886,14 +886,14 @@
     "section": "`u128` arithmetic",
     "input_type": "u128, u128",
     "output_type": "Option<u128>",
-    "description": "Subtract the second `u128` value from the first. Return `Some` of the difference, or `None` if the result would underflow `u128`."
+    "description": "Subtract the second `u128` value from the first. Return `Some` of the difference, or `None` if the result would overflow `u128`."
   },
   {
     "simplicityhl_name": "safe_sub_128",
     "section": "`u128` arithmetic",
     "input_type": "u128, u128",
     "output_type": "u128",
-    "description": "Subtract the second `u128` value from the first.\n\n## Panics\nPanics if the result would underflow `u128`."
+    "description": "Subtract the second `u128` value from the first.\n\n## Panics\nPanics if the result would overflow `u128`."
   },
   {
     "simplicityhl_name": "mul_128",
@@ -1173,14 +1173,14 @@
     "section": "`u256` arithmetic",
     "input_type": "u256, u256",
     "output_type": "Option<u256>",
-    "description": "Subtract the second `u256` value from the first. Return `Some` of the difference, or `None` if the result would underflow `u256`."
+    "description": "Subtract the second `u256` value from the first. Return `Some` of the difference, or `None` if the result would overflow `u256`."
   },
   {
     "simplicityhl_name": "safe_sub_256",
     "section": "`u256` arithmetic",
     "input_type": "u256, u256",
     "output_type": "u256",
-    "description": "Subtract the second `u256` value from the first.\n\n## Panics\nPanics if the result would underflow `u256`."
+    "description": "Subtract the second `u256` value from the first.\n\n## Panics\nPanics if the result would overflow `u256`."
   },
   {
     "simplicityhl_name": "mul_256",

simf/lib/u128/math.simf

@@ -351,7 +351,7 @@ pub fn div_mod_128(a: u128, b: u128) -> (u128, u128) {
                     match jet::eq_64(a_high, b_high) {
                         true => {
                             // safe: !lt_128(a, b) and a_high == b_high, so a_low >= b_low,
-                            // and the subtraction can not underflow
+                            // and the subtraction can not overflow
                             let (_, diff): (bool, u64) = jet::subtract_64(a_low, b_low);
                             (1, u64_to_u128(diff))
                         },

simf/lib/u256/math.simf

@@ -463,7 +463,7 @@ pub fn div_mod_256(a: u256, b: u256) -> (u256, u256) {
                     match eq_128(a_high, b_high) {
                         true => {
                             // safe: !lt_256(a, b) and a_high == b_high, so a_low >= b_low,
-                            // and the subtraction can not underflow
+                            // and the subtraction can not overflow
                             let (_, diff): (bool, u128) = sub_128(a_low, b_low);
                             (1, u128_to_u256(diff))
                         },