sys: util: Add gcd and lcm utilities

Add helpers to compute Greates Common Divisor (GCD) and Least Common
Multiple (LCM).

Signed-off-by: Phi Bang Nguyen <[email protected]>
Signed-off-by: Trung Hieu Le <[email protected]>

Author: ngphibang

include/zephyr/sys/util.h

@@ -1038,6 +1038,84 @@ static inline size_t sys_count_bits(const void *value, size_t len)
  */
 #define SIGN(x) (((x) > 0) - ((x) < 0))
 
+/**
+ * @brief Compute the Greatest Common Divisor (GCD) of two integers
+ * using the Euclidean algorithm.
+ *
+ * @param a First integer
+ * @param b Second integer
+ *
+ * @return The greatest common divisor of a and b, always returns a positive value.
+ *         If one of the parameters is 0, returns the absolute value of the other parameter.
+ */
+#define gcd(a, b) \
+	_Generic((a), \
+		int8_t : gcd_s, \
+		int16_t : gcd_s, \
+		int32_t : gcd_s, \
+		uint8_t : gcd_u, \
+		uint16_t : gcd_u, \
+		uint32_t : gcd_u)(a, b)
+
+static inline uint32_t gcd_u(uint32_t a, uint32_t b)
+{
+
+	if (a == 0) {
+		return b;
+	}
+
+	if (b == 0) {
+		return a;
+	}
+
+	uint32_t c = a % b;
+
+	while (c != 0) {
+		a = b;
+		b = c;
+		c = a % b;
+	}
+
+	return b;
+}
+
+static inline int32_t gcd_s(int32_t a, int32_t b)
+{
+	return gcd_u(a < 0 ? -a : a, b < 0 ? -b : b);
+}
+
+/**
+ * @brief Compute the Least Common Multiple (LCM) of two integers.
+ *
+ * @param a First integer
+ * @param b Second integer
+ *
+ * @retval The least common multiple of a and b.
+ * @retval 0 if either input is 0.
+ */
+#define lcm(a, b) \
+	_Generic((a), \
+		int8_t : lcm_s, \
+		int16_t : lcm_s, \
+		int32_t : lcm_s, \
+		uint8_t : lcm_u, \
+		uint16_t : lcm_u, \
+		uint32_t : lcm_u)(a, b)
+
+static inline uint32_t lcm_u(uint32_t a, uint32_t b)
+{
+	if (a == 0 || b == 0) {
+		return 0;
+	}
+
+	return (a / gcd_u(a, b)) * b;
+}
+
+static inline int32_t lcm_s(int32_t a, int32_t b)
+{
+	return lcm_u(a < 0 ? -a : a, b < 0 ? -b : b);
+}
+
 #ifdef __cplusplus
 }
 #endif