From 0e0884cce9d2c90174cc704478f6cacde6171160 Mon Sep 17 00:00:00 2001
From: Myles Busig <mdbusig@gmail.com>
Date: Sat, 3 Aug 2024 16:18:20 -0600
Subject: [PATCH] Add noexcept specifier to fixed point operations

---
 include/mtl/fixed.hpp | 36 ++++++++++++++++++------------------
 src/gba/fixed.cpp     |  2 +-
 2 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/include/mtl/fixed.hpp b/include/mtl/fixed.hpp
index f634a03..8114ebb 100644
--- a/include/mtl/fixed.hpp
+++ b/include/mtl/fixed.hpp
@@ -17,12 +17,12 @@ namespace mtl {
  * Valid values are in the range ~[-33'554'431.01, 33'554'432.98]
  *
  * Has a maximum error of +/- 1/128 (~0.0078), integers are always
- * exactly.
+ * exactly represented.
  *
  * \par ARM
  *
- * All functions are compiled in ARM mode because some operators (notably
- * multiplication and division) use ARM-only instructions. For optimal
+ * All functions are compiled in ARM-mode because some operators (notably
+ * multiplication and division) are much faster in ARM-mode. For optimal
  * performance, fixed point numbers should only be used in ARM-mode
  * code to enable as much inlining as possible.
  */
@@ -44,10 +44,10 @@ private:
 	 * DO NOT use to set the fixed number to an integer value, use
 	 * the public constructor instead.
 	 */
-	constexpr fixed(int32_t _x, bool) : x(_x) {}
+	constexpr fixed(int32_t _x, bool) noexcept : x(_x) {}
 
 public:
-	constexpr fixed() : x(0) {}
+	constexpr fixed() noexcept : x(0) {}
 	/**
 	 * \brief Integer constructor
 	 *
@@ -56,7 +56,7 @@ public:
 	 * the class description for more detail.
 	 */
 	template <typename T, std::enable_if_t<std::is_integral_v<T>, bool> = true>
-	constexpr fixed(T _i) : x(_i * 64) {}
+	constexpr fixed(T _i) noexcept : x(_i * 64) {}
 	/**
 	 * \brief Floating point constructor
 	 *
@@ -69,7 +69,7 @@ public:
 	 * float.
 	 */
 	template <typename T, std::enable_if_t<std::is_floating_point_v<T>, bool> = true>
-	constexpr fixed(T _f)
+	constexpr fixed(T _f) noexcept
 		// 0.5 offset accounts for truncating to integer, round instead
 		: x((_f * 64) + 0.5f) {}
 
@@ -82,7 +82,7 @@ public:
 	 *
 	 * Should not be used unless absolutely needed.
 	 */
-	static constexpr fixed from_raw(int32_t x) {
+	static constexpr fixed from_raw(int32_t x) noexcept {
 		return fixed(x, true);
 	}
 
@@ -92,7 +92,7 @@ public:
 	 * Gets the raw value of the fixed point number. i.e. The fixed point
 	 * number multiplied by 64.
 	 */
-	constexpr int32_t raw() const {
+	constexpr int32_t raw() const noexcept {
 		return x;
 	}
 
@@ -102,34 +102,34 @@ public:
 	 * Addition with fixed point numbers is the same as with a 32-bit
 	 * integer, so should be extremely quick.
 	 */
-	constexpr fixed operator+(fixed rhs) const {
+	constexpr fixed operator+(fixed rhs) const noexcept {
 		return from_raw(x + rhs.x);
 	}
-	constexpr fixed& operator+=(fixed rhs) {
+	constexpr fixed& operator+=(fixed rhs) noexcept {
 		x += rhs.x;
 		return *this;
 	}
 	/**
 	 * \brief Fixed point subtraction
 	 */
-	constexpr fixed operator-(fixed rhs) const {
+	constexpr fixed operator-(fixed rhs) const noexcept {
 		return from_raw(x - rhs.x);
 	}
-	constexpr fixed& operator-=(fixed rhs) {
+	constexpr fixed& operator-=(fixed rhs) noexcept {
 		x -= rhs.x;
 		return *this;
 	}
-	constexpr fixed operator-() const {
+	constexpr fixed operator-() const noexcept {
 		return from_raw(-x);
 	}
 
 	/**
 	 * \brief Fixed point multiplication
 	 */
-	constexpr fixed operator*(fixed rhs) const {
+	constexpr fixed operator*(fixed rhs) const noexcept {
 		return from_raw(((int64_t)x * rhs.x) >> 6);
 	}
-	constexpr fixed& operator*=(fixed rhs) {
+	constexpr fixed& operator*=(fixed rhs) noexcept {
 		*this = *this * rhs;
 		return *this;
 	}
@@ -149,8 +149,8 @@ public:
 	 *
 	 * Placed in IWRAM
 	 */
-	GBA_IWRAM fixed operator/(fixed rhs) const;
-	fixed& operator/=(fixed rhs) {
+	GBA_IWRAM fixed operator/(fixed rhs) const noexcept;
+	fixed& operator/=(fixed rhs) noexcept {
 		*this = *this / rhs;
 		return *this;
 	}
diff --git a/src/gba/fixed.cpp b/src/gba/fixed.cpp
index d33deeb..baf4ca4 100644
--- a/src/gba/fixed.cpp
+++ b/src/gba/fixed.cpp
@@ -6,7 +6,7 @@ TARGET_ARM_MODE
 
 namespace mtl {
 
-fixed fixed::operator/(fixed rhs) const {
+fixed fixed::operator/(fixed rhs) const noexcept {
 	int32_t raw_result;
 	asm(
 			// This division implementation has two methods it can use.