Merge pull request #1607 from AyiStar/add-math-const

Add math constants corresbonding to `util/math_constants.h` for FixedPoint
SFTtech · Dec 4, 2023 · 3c3de39 · 3c3de39
2 parents 2391847 + 83dc9d5
commit 3c3de39
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diff --git a/libopenage/util/fixed_point.h b/libopenage/util/fixed_point.h
@@ -53,8 +53,8 @@ constexpr static
 
 
 /**
- * Helper function that performs either a safe shift-right (amount > 0),
- * or a safe shift-left (amount < 0).
+ * Helper function that performs either a safe shift-right (amount < 0),
+ * or a safe shift-left (amount >= 0).
  */
 template <int amount, typename T>
 constexpr static
@@ -169,6 +169,74 @@ class FixedPoint {
 		return FixedPoint::from_int(0);
 	}
 
+	/**
+	 * Math constants represented in FixedPoint
+	 */
+	// naming, definition and value are kept compatible with `math_constants.h`
+	static constexpr FixedPoint e() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(6267931151224907085ll));
+	}
+
+	static constexpr FixedPoint log2e() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(3326628274461080622ll));
+	}
+
+	static constexpr FixedPoint log10e() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(1001414895036696345ll));
+	}
+
+	static constexpr FixedPoint ln2() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(1598288580650331957ll));
+	}
+
+	static constexpr FixedPoint ln10() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(5309399739799983627ll));
+	}
+
+	static constexpr FixedPoint pi() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(7244019458077122842ll));
+	}
+
+	static constexpr FixedPoint pi_2() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(3622009729038561421ll));
+	}
+
+	static constexpr FixedPoint pi_4() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(1811004864519280710ll));
+	}
+
+	static constexpr FixedPoint inv_pi() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(733972625820500306ll));
+	}
+
+	static constexpr FixedPoint inv2_pi() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(1467945251641000613ll));
+	}
+
+	static constexpr FixedPoint inv2_sqrt_pi() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(2601865214189558307ll));
+	}
+
+	static constexpr FixedPoint tau() {
+		return from_fixedpoint(FixedPoint<int64_t, 60>::from_raw_value(7244019458077122842ll));
+	}
+
+	static constexpr FixedPoint degs_per_rad() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(40244552544872904ll));
+	}
+
+	static constexpr FixedPoint rads_per_deg() {
+		return from_fixedpoint(FixedPoint<int64_t, 57>::from_raw_value(8257192040480628449ll));
+	}
+
+	static constexpr FixedPoint sqrt_2() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(3260954456333195553ll));
+	}
+
+	static constexpr FixedPoint inv_sqrt_2() {
+		return from_fixedpoint(FixedPoint<int64_t, 61>::from_raw_value(1630477228166597776ll));
+	}
+
 	/**
 	 * Factory function to get a fixed-point number from an integer.
 	 */
@@ -193,10 +261,16 @@ class FixedPoint {
 	/**
 	 * Factory function to get a fixed-point number from a fixed-point number of different type.
 	 */
-	template <typename other_int_type, unsigned int other_fractional_bits>
+	template <typename other_int_type, unsigned int other_fractional_bits, typename std::enable_if<(fractional_bits > other_fractional_bits)>::type* = nullptr>
+	static constexpr FixedPoint from_fixedpoint(const FixedPoint<other_int_type, other_fractional_bits> &other) {
+		return FixedPoint::from_raw_value(
+			safe_shift<fractional_bits - other_fractional_bits, int_type>(static_cast<int_type>(other.get_raw_value())));
+	}
+
+	template <typename other_int_type, unsigned int other_fractional_bits, typename std::enable_if<(fractional_bits <= other_fractional_bits)>::type* = nullptr>
 	static constexpr FixedPoint from_fixedpoint(const FixedPoint<other_int_type, other_fractional_bits> &other) {
 		return FixedPoint::from_raw_value(
-			safe_shift<fractional_bits - other_fractional_bits, int_type>(other.get_raw_value()));
+			static_cast<int_type>(other.get_raw_value() / safe_shiftleft<other_fractional_bits - fractional_bits, other_int_type>(1)));
 	}
 
 	/**

diff --git a/libopenage/util/fixed_point_test.cpp b/libopenage/util/fixed_point_test.cpp
@@ -6,6 +6,7 @@
 
 #include "../testing/testing.h"
 #include "stringformatter.h"
+#include "math_constants.h"
 
 namespace openage {
 namespace util {
@@ -98,6 +99,29 @@ void fixed_point() {
 	std::stringstream sstr("1234.5678");
 	sstr >> e;
 	TESTEQUALS_FLOAT(e.to_double(), 1234.5678, 1e-7);
+
+	TESTEQUALS_FLOAT(TestType::e().to_double(), math::E, 1e-7);
+	TESTEQUALS_FLOAT(TestType::log2e().to_double(), math::LOG2E, 1e-7);
+	TESTEQUALS_FLOAT(TestType::log10e().to_double(), math::LOG10E, 1e-7);
+	TESTEQUALS_FLOAT(TestType::ln2().to_double(), math::LN2, 1e-7);
+	TESTEQUALS_FLOAT(TestType::ln10().to_double(), math::LN10, 1e-7);
+	TESTEQUALS_FLOAT(TestType::pi().to_double(), math::PI, 1e-7);
+	TESTEQUALS_FLOAT(TestType::pi_2().to_double(), math::PI_2, 1e-7);
+	TESTEQUALS_FLOAT(TestType::pi_4().to_double(), math::PI_4, 1e-7);
+	TESTEQUALS_FLOAT(TestType::inv_pi().to_double(), math::INV_PI, 1e-7);
+	TESTEQUALS_FLOAT(TestType::inv2_pi().to_double(), math::INV2_PI, 1e-7);
+	TESTEQUALS_FLOAT(TestType::inv2_sqrt_pi().to_double(), math::INV2_SQRT_PI, 1e-7);
+	TESTEQUALS_FLOAT(TestType::tau().to_double(), math::TAU, 1e-7);
+	TESTEQUALS_FLOAT(TestType::degs_per_rad().to_double(), math::DEGSPERRAD, 1e-7);
+	TESTEQUALS_FLOAT(TestType::rads_per_deg().to_double(), math::RADSPERDEG, 1e-7);
+	TESTEQUALS_FLOAT(TestType::sqrt_2().to_double(), math::SQRT_2, 1e-7);
+	TESTEQUALS_FLOAT(TestType::inv_sqrt_2().to_double(), math::INV_SQRT_2, 1e-7);
+
+
+	using TestTypeShort = FixedPoint<int32_t, 16>;
+	TESTEQUALS_FLOAT(TestTypeShort::e().to_double(), math::E, 1e-3);
+	TESTEQUALS_FLOAT(TestTypeShort::pi().to_double(), math::PI, 1e-3);
+
 }
 
 }}} // openage::util::tests