Updated the doc

README.md

@@ -1,2 +1,64 @@
-Frozen: JSON parser and generator for ISO C
+JSON parser and generator for ISO C
 ===========================================
+
+## Features
+
+   * Written in strict ISO C
+   * No dependencies, even libc is not required
+   * Simple API: one function for parsing, one function for generation
+   * Supports superset of JSON: allows non-quoted identifiers as object keys
+   * Very fast, does one pass
+   * Makes no memory allocations
+
+## API
+
+    int parse_json(const char *json_string, int json_string_length,
+                   struct json_token *tokens_array, int size_of_tokens_array);
+
+Tokenizes `json_string` of length `json_string_length`.
+If `tokens_array` is not `NULL`, then
+all `parse_json` will store tokens in the `tokens_array`. Token with type
+`JSON_TYPE_EOF` marks the end of parsed tokens. JSON token is defined as:
+
+    struct json_token {
+      const char *ptr;    // Points to the beginning of the token
+      int len;            // Token length
+      int type;           // Type of the token, possible values below
+
+    #define JSON_TYPE_EOF     0   // Not a real token. This is a marker
+    #define JSON_TYPE_STRING  1
+    #define JSON_TYPE_NUMBER  2
+    #define JSON_TYPE_OBJECT  3
+    #define JSON_TYPE_TRUE    4
+    #define JSON_TYPE_FALSE   5
+    #define JSON_TYPE_NULL    6
+    #define JSON_TYPE_ARRAY   7
+    };
+
+If `tokens_array` is `NULL`, then `parse_json` just checks the validity of
+the JSON string, and points where parsing stops. If `tokens_array` is not
+`NULL`, it must be pre-allocated by the caller.  
+Return: On success, an offset inside `json_string` is returned
+where parsing has finished. On failure, a negative number is
+returned, one of:
+
+    #define JSON_STRING_INVALID           -1
+    #define JSON_STRING_INCOMPLETE        -2
+    #define JSON_TOKEN_ARRAY_TOO_SMALL    -3
+    #define JSON_OUTPUT_BUFFER_TOO_SMALL  -4
+
+<!-- -->
+
+    const struct json_token *find_json_token(const struct json_token *toks,
+                                             const char *path);
+
+This is a convenience function to fetch specific values from the parsed
+string. `toks` must be a valid array, successfully populated by `parse_json()`.
+A `path` is a string, an accessor to the desired element of the JSON object,
+as if it was written in Javascript. For example, if parsed JSON string is
+"{ foo : { bar: [1, 2, 3] } }", then path "foo.bar[0]" would return a token
+that points to number "1".  
+Return: pointer to the found token, or NULL on failure.
+
+## Example: parsing configuration
+