* updated README with source path descriptions

* updated xmodem receiver states to match diagram

README.md

@@ -10,7 +10,7 @@ Setup Environment - Ubuntu 16.10
 sudo apt-get install build-essential socat lrzsz minicom ant git libgtest-dev cmake
 ```
 
-Build and install libXMODEM 
+Build and install libXMODEM
 --------------------------------
 ```bash
 git clone [email protected]:caseykelso/xmodem.git
@@ -22,7 +22,7 @@ make install -j8
 ```
 
 # Development
-For developers looking to extend, bug fix, build, and test libXMODEM with dependencies and test infrastructure included in the source tree.
+For developers looking to extend, bug fix, build, and test libXMODEM with dependencies and test infrastructure included in the source tree. The complete source tree grabs third party repos, standalone command line application code, serial port lib, and gtest.
 
 Setup Environment - OSX
 ------------------------
@@ -76,7 +76,7 @@ make
 ```
 
 Build Library - Bare Metal
--------------------------- 
+--------------------------
 TBD
 
 # Tests
@@ -89,7 +89,11 @@ Build & Run Unit Tests
 ant tests
 ```
 
-Unit testing is implemented with Google's GTest.
+## High-level Tests
+Open a terminal
+```bash
+ant tests_system
+```
 
 ### Transmit State Machine
 All transitions are covered via unit tests.
@@ -101,9 +105,74 @@ All transitions are covered via unit tests.
 
 <img src="documentation/xmodem_receive_fsm.png"  />
 
-## High-level Tests
-Open a terminal
+
+# Project Structure
+## Source Directories
+* /source - libxmodem source directory
+  * xmodem.h - common header (transmitter and receiver)
+  * xmodem.c - common implementation (transmitter and receiver)
+  * xmodem_receiver.h - receiver side header
+  * xmodem_receiver.c - receiver side implementation
+  * xmodem_transmitter.h - transmitter side header
+  * xmodem_transmitter.c - transmitter side implementation
+
+
+* /app    - application level source directory
+  * CMakeLists.txt - cmake build configuration for the commandline app
+  * main.cpp - main application source code file
+  * serialport.cpp - thin abstraction for asio serialport
+  * serialport.h - header for thin abstraction for asio serialport
+
+
+* /tests
+  * CMakeLists.txt - cmake build configuration for the test runner
+  * test.cpp - libxmodem test implementation
+  * XModemTests.cpp - gtest test suite (implementation is in header)
+  * XModemTests.h - gtest test suite definition and SetUp() TearDown() implementation
+
+
+* /tests.tmp - temporary folder for test files and virtual serial port nodes
+
+
+* /
+  * build.xml - ant build configuration for aggregate project (only used for standalone dev purposes not integration). Allows for easy development in Linux, OSX, and Windows
+  * CMakeLists.txt - libxmodem cmake build configuration, used for integrators who wish to clone just the libxmodem source tree without using git-repo for aggregation.
+  * README.md - this file
+  * xmodem.xml - git-repo manifest definition to aggregate all project dependencies for libxmodem development purposes
+  * .gitignore - definitions of files and directories to be ignored by git
+
+
+## Third Party Source Directories
+* /asio    - boost asynchronous IO standalone implementation
+* /cmake   - latest cmake build tool - tip of master branch
+* /docopt  - library for commandline switches
+* /gtest   - google test library
+
+## Build Directories
+* build - libxmodem library build directory
+* build.app - application build directory
+* build.docopt - libdocopt build directory
+* build.tests - unit test runner build directory
+* build.gtest - google test build directory
+
+# Commandline Application Usage
 ```bash
-ant tests_system
+nanoXmodem:
+
+	    Usage:
+	      x --port=<port> --receive  --file=<filename> [--baud=<baudrate>]
+	      x --port=<port> --transmit --file=<filename> [--baud=<baudrate>]
+              x --enumerate
+	      x (-h | --help)
+	      x --version
+
+	    Options:
+	      -h --help           Show this screen.
+	      --version           Show version.
+	      --port=<comport>    Path to comport.
+	      --baud=<baudrate>   Baudrate [default: 115200].
+	      --receive           Start transfer as receiver.
+	      --transmit          Start file transmission.
+              --enumerate         Enumerate list of available ports.
+	      --file=<filename>   File to send.
 ```
-