atmel-samd: Introduce a nvm module for non-volatile byte-level memory access. (#203)

* atmel-samd: Introduce a nvm module for non-volatile byte-level memory access.

This allows for persisting small configuration values even when the file system
is read-only from CircuitPython.

Fixes #160

* Review feedback:
* Add tests.
* Fix non-zero index.
* Fix len()

1 files changed, 11 insertions, 0 deletions

diff --git a/tests/skip_if.py b/tests/skip_if.py
index f6d22b4c1..7b1e06871 100644
--- a/tests/skip_if.py
+++ b/tests/skip_if.py
@@ -52,6 +52,17 @@ def board_in(*board):
     if test_env.board in board:
         skip()
 
+def board_not_in(*board):
+    try:
+        import test_env
+    except ImportError:
+        class Env:
+            def __init__(self, board):
+                self.board = board
+        test_env = Env("unknown")
+    if test_env.board not in board:
+        skip()
+
 def no_cpython_compat():
     try:
         try: