Add pre-commit support for sanity checks

Use pre-commit framework [1] to run black and flake8 before the commit.
black and flake8 are managed by the pre-commit framework and they can be
run manually by the user using `pre-commit run` command.

Fix the code base with the help of black and flake8.
Fix import statements according to PEP8 guidelines [1]
Both tools have the following settings (specified in the pre-commit
configuration file):
* line length: 120 characters
* directory to exclude: ethosu/vela/tflite/ and ethosu/vela/ethos_u55_regs

Updated README.md on how to install pre-commit and how to run sanity checks.
Pipenv files have been updated including new dependencies for pre-commit.

[1]: https://www.python.org/dev/peps/pep-0008/#imports
[2]: https://github.com/pre-commit/pre-commit

Change-Id: I304d9fffdf019d390ffa396a529c8a7c2437f63d
Signed-off-by: Diego Russo <diego.russo@arm.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/ethosu/vela/stats_writer.py b/ethosu/vela/stats_writer.py
index c4b4cd9e..3fd29d12 100644
--- a/ethosu/vela/stats_writer.py
+++ b/ethosu/vela/stats_writer.py
@@ -18,12 +18,15 @@
 # Description:
 # Writes out per-pass and summary performance statistics to CSV files.
 
+import csv
+import sys
+
 import numpy as np
-from .nn_graph import MemArea, TensorPurpose, PassPlacement
+
+from .tensor import MemArea, TensorPurpose
+from .nn_graph import PassPlacement
 from .npu_performance import PassCycles, MacCount, BandwidthDirection
-import csv
 from .numeric_util import round_up_to_int
-import sys
 
 
 def write_summary_metrics_csv(nng, summary_filename, arch):
@@ -246,7 +249,7 @@ def print_performance_metrics_for_strat(
 
     print(file=f)
     for mem_area, label in mem_area_labels:
-        if not mem_area in memory_used:
+        if mem_area not in memory_used:
             continue
 
         aug_label = label + " used"