Update README.md

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Author: devatrun

README.md

@@ -1,2 +1,60 @@
-# slimcpp
-Simple Long Integer Math for C++
+# SLIMCPP
+# Simple long integer math libtary for C++
+This library implements long integers that exceed maximum size of native type supported by a specific compiler by 2-4 times. In some cases, it is necessary to temporarily perform calculations with precision exceeding the maximum supported size of integers, and then return the result to its native size again. 
+The main features:
+* easy to use: the library is header-only
+* small: consists of few header files, there is no dependencies
+* speed: use intrinsics if supported
+* cross-platform: supports MSVC, GCC and CLANG C++17 compilers
+
+Library implements two main classes:
+```c++
+template<typename native_t = uintmax_t, uint_t size = 2>
+class long_uint_t; // unsigned integer
+template<typename native_t = uintmax_t, uint_t size = 2>
+class long_int_t;  // signed integer
+```
+where native_t may be one of base unsigned type and size must by power of two.
+## Integration
+Library implements four predefined types: uint128_t, uint256_t, int128_t, int256_t. You can use them in you project by include code below:
+```c++
+#include <slimcpplib/long_int.h>
+
+namespace your_namespace
+{
+    using uint128_t = slim::uint128_t;
+    using uint256_t = slim::uint256_t;
+    using int128_t  = slim::int128_t;
+    using int256_t  = slim::int256_t;
+    using namespace slim::literals;
+
+} // namespace your_namespace
+```
+## Constant declaration:
+```c++
+constexpr auto uo = 03766713523035452062041773345651416625031020_ui128;     // octal unsigned integer
+constexpr auto ud = 338770000845734292534325025077361652240_ui128;          // decimal unsigned integer
+constexpr auto uh = 0xfedcba9876543210fedcba9876543210_ui128;               // hexadecimal unsigned integer
+
+constexpr auto io = -03766713523035452062041773345651416625031020_si128;    // octal signed integer
+constexpr auto id = -338770000845734292534325025077361652240_si128;         // decimal signed integer
+constexpr auto ih = -0xfedcba9876543210fedcba9876543210_si128;              // hexadecimal signed integer
+```
+also supported (') separator for integer literals:
+```c++
+constexpr auto u = 0xfedcba98'76543210'fedcba98'76543210_ui128;            // hexadecimal unsigned integer
+```
+## Construction:
+```c++
+const uint128_t u;                  // construct uninitialized unsigned integer
+const uint128_t u = 1U;             // construction from unsigned integer
+const int128_t  s = -1;             // construction from signed integer
+const uint128_t u = 10000_ui128;    // construction from long unsigned integer
+const int128_t  u = -10000_i128;    // construction from long signed integer
+const uint128_t u = true;           // construction from boolean value
+```
+## Operators
+long_uint_t type supports following operators:
+==, !=, <, <=, >, >=, <<=, <<, >>=, >>, +=, +, ++, -=, -, --, *=, *, /=, /, %=, %, ~, &=, &, |=, |, ^=, ^
+long_int_t type supports following operators:
+==, !=, <, <=, >, >=, <<=, <<, >>=, >>, +=, +, ++, -=, -, --, *=, *, /=, /, %=, %