From 05e9d76c772881f5691874c3e11f0a9714bcd166 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Fri, 14 Jun 2024 11:04:29 +0300
Subject: [PATCH] BAN: Implement will_{addition,multiplication}_overflow

---
 BAN/include/BAN/Math.h | 22 ++++++++++++++++++++++
 libc/stdlib.cpp        | 27 +++------------------------
 2 files changed, 25 insertions(+), 24 deletions(-)

diff --git a/BAN/include/BAN/Math.h b/BAN/include/BAN/Math.h
index 617d330914..78a7794172 100644
--- a/BAN/include/BAN/Math.h
+++ b/BAN/include/BAN/Math.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <BAN/Limits.h>
 #include <BAN/Traits.h>
 
 #include <stddef.h>
@@ -65,6 +66,27 @@ namespace BAN::Math
 		return (value & (value - 1)) == 0;
 	}
 
+	template<BAN::integral T>
+	static constexpr bool will_multiplication_overflow(T a, T b)
+	{
+		if (a == 0 || b == 0)
+			return false;
+		if ((a > 0) == (b > 0))
+			return a > BAN::numeric_limits<T>::max() / b;
+		else
+			return a < BAN::numeric_limits<T>::min() / b;
+	}
+
+	template<BAN::integral T>
+	static constexpr bool will_addition_overflow(T a, T b)
+	{
+		if (a > 0 && b > 0)
+			return a > BAN::numeric_limits<T>::max() - b;
+		if (a < 0 && b < 0)
+			return a < BAN::numeric_limits<T>::min() - b;
+		return false;
+	}
+
 	template<typename T>
 	requires is_same_v<T, unsigned int> || is_same_v<T, unsigned long> || is_same_v<T, unsigned long long>
 	inline constexpr T ilog2(T value)
diff --git a/libc/stdlib.cpp b/libc/stdlib.cpp
index 5fae412870..bdfe27a25e 100644
--- a/libc/stdlib.cpp
+++ b/libc/stdlib.cpp
@@ -64,35 +64,14 @@ static constexpr int get_base_digit(char c, int base)
 	return -1;
 }
 
-template<BAN::integral T>
-static constexpr bool will_multiplication_overflow(T a, T b)
-{
-	if (a == 0 || b == 0)
-		return false;
-	if ((a > 0) == (b > 0))
-		return a > BAN::numeric_limits<T>::max() / b;
-	else
-		return a < BAN::numeric_limits<T>::min() / b;
-}
-
-template<BAN::integral T>
-static constexpr bool will_addition_overflow(T a, T b)
-{
-	if (a > 0 && b > 0)
-		return a > BAN::numeric_limits<T>::max() - b;
-	if (a < 0 && b < 0)
-		return a < BAN::numeric_limits<T>::min() - b;
-	return false;
-}
-
 template<BAN::integral T>
 static constexpr bool will_digit_append_overflow(bool negative, T current, int digit, int base)
 {
 	if (BAN::is_unsigned_v<T> && negative && digit)
 		return true;
-	if (will_multiplication_overflow<T>(current, base))
+	if (BAN::Math::will_multiplication_overflow<T>(current, base))
 		return true;
-	if (will_addition_overflow<T>(current * base, current < 0 ? -digit : digit))
+	if (BAN::Math::will_addition_overflow<T>(current * base, current < 0 ? -digit : digit))
 		return true;
 	return false;
 }
@@ -286,7 +265,7 @@ static T strtoT(const char* str, char** endp, int& error)
 		int extra_exponent = strtoT<int>(str + 1, &maybe_end, 10, exp_error);
 		if (exp_error != EINVAL)
 		{
-			if (exp_error == ERANGE || will_addition_overflow(exponent, extra_exponent))
+			if (exp_error == ERANGE || BAN::Math::will_addition_overflow(exponent, extra_exponent))
 				exponent = negative ? BAN::numeric_limits<int>::min() : BAN::numeric_limits<int>::max();
 			else
 				exponent += extra_exponent;