Make git dependency visible and enforce it.

resolves #87

README.md

@@ -32,6 +32,7 @@ The OpenRAM compiler has very few dependencies:
 + [Ngspice] 26 (or later) or HSpice I-2013.12-1 (or later) or CustomSim 2017 (or later) or [Xyce] 7.2 (or later)
 + Python 3.5 or higher
 + Various Python packages (pip install -r requirements.txt)
++ [Git]
 
 If you want to perform DRC and LVS, you will need either:
 + Calibre (for [FreePDK45])
@@ -215,6 +216,7 @@ If I forgot to add you, please let me know!
 [Qflow]:                 http://opencircuitdesign.com/qflow/history.html
 [Ngspice]:               http://ngspice.sourceforge.net/
 [Xyce]:                  http://xyce.sandia.gov/
+[Git]:                   https://git-scm.com/
 
 [OSUPDK]:                https://vlsiarch.ecen.okstate.edu/flow/
 [FreePDK45]:             https://www.eda.ncsu.edu/wiki/FreePDK45:Contents

compiler/characterizer/lib.py

@@ -762,7 +762,7 @@ class lib:
 
         else:
             with open(os.devnull, 'wb') as devnull:
-                # parses the mose recent git commit id - requres git is installed
+                # parses the most recent git commit id - reason for global git dependancy
                 proc = subprocess.Popen(['git','rev-parse','HEAD'], cwd=os.path.abspath(os.environ.get("OPENRAM_HOME")) + '/', stdout=subprocess.PIPE)
 
                 git_id = str(proc.stdout.read())

compiler/globals.py

@@ -159,6 +159,13 @@ def check_versions():
     if not (major_python_version == major_required and minor_python_version >= minor_required):
         debug.error("Python {0}.{1} or greater is required.".format(major_required, minor_required), -1)
 
+    # Verify any version of git is isntalled before proceeding
+    try:
+        subprocess.check_output(["git", "--version"])
+    except:
+        debug.error("Git is required. Please install git.")
+        sys.exit(1)
+
     # FIXME: Check versions of other tools here??
     # or, this could be done in each module (e.g. verify, characterizer, etc.)
     global OPTS