make Base64EncodingBufferSize constexpr

libi2pd/Base.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2023, The PurpleI2P Project
+* Copyright (c) 2013-2025, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -11,27 +11,41 @@
 
 #include <inttypes.h>
 #include <string>
-#include <iostream>
+#include <string_view>
+#include <cstdlib>
 
-namespace i2p {
-namespace data {
+namespace i2p 
+{
+namespace data 
+{
 	size_t ByteStreamToBase64 (const uint8_t * InBuffer, size_t InCount, char * OutBuffer, size_t len);
 	size_t Base64ToByteStream (const char * InBuffer, size_t InCount, uint8_t * OutBuffer, size_t len );
 	const char * GetBase32SubstitutionTable ();
 	const char * GetBase64SubstitutionTable ();
-	bool IsBase64 (char ch);
+	constexpr bool IsBase64 (char ch)
+	{
+		return (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9') || ch == '-' || ch == '~';
+	}	
 
 	size_t Base32ToByteStream (const char * inBuf, size_t len, uint8_t * outBuf, size_t outLen);
 	size_t ByteStreamToBase32 (const uint8_t * InBuf, size_t len, char * outBuf, size_t outLen);
-	bool IsBase32 (char ch);
+	constexpr bool IsBase32 (char ch)
+	{
+		return (ch >= 'a' && ch <= 'z') || (ch >= '2' && ch <= '7');
+	}	
 
 	/**
 	 * Compute the size for a buffer to contain encoded base64 given that the size of the input is input_size bytes
 	 */
-	size_t Base64EncodingBufferSize(const size_t input_size);
-
-	std::string ToBase64Standard (const std::string& in); // using standard table, for Proxy-Authorization
+	constexpr size_t Base64EncodingBufferSize(size_t input_size)
+	{
+		auto d = std::div (input_size, 3);
+		if (d.rem) d.quot++;
+		return 4 * d.quot;
+	}	
 
+	std::string ToBase64Standard (std::string_view in); // using standard table, for Proxy-Authorization
+	
 } // data
 } // i2p