refactor: improve function signatures and type safety in llcc68 definitions

- Removed unnecessary include of <cstddef>.
- Updated function signatures to use trailing return types and added [[nodiscard]] attribute for better safety and clarity.
- Standardized float literals to use uppercase 'F' for consistency.
- Simplified the valid_ldr_optimize function for improved readability.

inc/llcc68_definitions.hpp

@@ -4,7 +4,6 @@
 
 #ifndef LLCC68_DEFINITIONS_H
 #define LLCC68_DEFINITIONS_H
-#include <cstddef>
 #include <cstdint>
 #include <optional>
 #include <string>
@@ -112,7 +111,8 @@ struct modulation_params_t {
 		};
 	}
 
-	std::string to_string() const {
+	[[nodiscard]]
+	auto to_string() const -> std::string {
 		return std::format("mod_params: bw={}, sf={}, cr={}, ldr_optimize={}",
 						   bw_to_string(static_cast<LoRaBandwidth>(bw)),
 						   sf,
@@ -256,16 +256,19 @@ struct __attribute__((packed)) lora_packet_status_t {
 	// Actual Rssi in dB = -SignalRssiPkt/2
 	uint8_t signal_rssi_pkt;
 
-	float rssi_pkt_dbm() const {
-		return -rssi_pkt / 2.0f;
+	[[nodiscard]]
+	auto rssi_pkt_dbm() const -> float {
+		return -rssi_pkt / 2.0F;
 	}
 
-	float snr_pkt_db() const {
-		return snr_pkt / 4.0f;
+	[[nodiscard]]
+	auto snr_pkt_db() const -> float {
+		return snr_pkt / 4.0F;
 	}
 
-	float signal_rssi_pkt_dbm() const {
-		return -signal_rssi_pkt / 2.0f;
+	[[nodiscard]]
+	auto signal_rssi_pkt_dbm() const -> float {
+		return -signal_rssi_pkt / 2.0F;
 	}
 };
 
@@ -344,10 +347,7 @@ cr_to_ratio(const uint8_t cr) {
 }
 
 constexpr bool valid_ldr_optimize(const uint8_t ldr_optimize) {
-	if (ldr_optimize > RADIOLIB_SX126X_LORA_LOW_DATA_RATE_OPTIMIZE_ON) {
-		return false;
-	}
-	return true;
+	return static_cast<bool>(ldr_optimize <= RADIOLIB_SX126X_LORA_LOW_DATA_RATE_OPTIMIZE_ON);
 }
 
 constexpr bool valid_bw(const uint8_t bw) {
@@ -372,25 +372,25 @@ using bw_t = float;
 constexpr bw_t bw_khz(const uint8_t bw) {
 	switch (bw) {
 	case RADIOLIB_SX126X_LORA_BW_7_8:
-		return bw_t{7.8f};
+		return bw_t{7.8F};
 	case RADIOLIB_SX126X_LORA_BW_10_4:
-		return bw_t{10.4f};
+		return bw_t{10.4F};
 	case RADIOLIB_SX126X_LORA_BW_15_6:
-		return bw_t{15.6f};
+		return bw_t{15.6F};
 	case RADIOLIB_SX126X_LORA_BW_20_8:
-		return bw_t{20.8f};
+		return bw_t{20.8F};
 	case RADIOLIB_SX126X_LORA_BW_31_25:
-		return bw_t{31.25f};
+		return bw_t{31.25F};
 	case RADIOLIB_SX126X_LORA_BW_41_7:
-		return bw_t{41.7f};
+		return bw_t{41.7F};
 	case RADIOLIB_SX126X_LORA_BW_62_5:
-		return bw_t{62.5f};
+		return bw_t{62.5F};
 	case RADIOLIB_SX126X_LORA_BW_125_0:
-		return bw_t{125.0f};
+		return bw_t{125.0F};
 	case RADIOLIB_SX126X_LORA_BW_250_0:
-		return bw_t{250.0f};
+		return bw_t{250.0F};
 	case RADIOLIB_SX126X_LORA_BW_500_0:
-		return bw_t{500.0f};
+		return bw_t{500.0F};
 	default:
 		return bw_t{0};
 	}