MLECO-718: Minor imporovements to source gen

Changes:
 * minor speed up for tflite to C++ file generation
 * virtual env's pip upgrade before installation of packages

Change-Id: If8cef85779b7381f444f608b565da0b8f994d364

2 files changed, 44 insertions, 27 deletions

diff --git a/scripts/cmake/source_gen_utils.cmake b/scripts/cmake/source_gen_utils.cmake
index 92ec53d..9d27b4d 100644
--- a/scripts/cmake/source_gen_utils.cmake
+++ b/scripts/cmake/source_gen_utils.cmake
@@ -272,22 +272,38 @@ function(setup_source_generator)
         message(STATUS "Using existing python at ${PYTHON}")
         return()
     endif ()
+
     message(STATUS "Configuring python environment at ${PYTHON}")
+
     execute_process(
         COMMAND ${PY_EXEC} -m venv ${CMAKE_BINARY_DIR}/pyenv
         RESULT_VARIABLE return_code
     )
+    if (NOT return_code STREQUAL "0")
+        message(FATAL_ERROR "Failed to setup python3 environment. Return code: ${return_code}")
+    endif ()
+
+    execute_process(
+        COMMAND ${PYTHON} -m pip install --upgrade pip
+        RESULT_VARIABLE return_code
+    )
     if (NOT return_code EQUAL "0")
-        message(FATAL_ERROR "Failed to setup python3 environment")
+        message(FATAL_ERROR "Failed to upgrade pip")
     endif ()
 
-    execute_process(COMMAND ${PYTHON} -m pip install wheel)
+    execute_process(
+        COMMAND ${PYTHON} -m pip install wheel
+        RESULT_VARIABLE return_code
+    )
+    if (NOT return_code EQUAL "0")
+        message(FATAL_ERROR "Failed to install wheel")
+    endif ()
 
     execute_process(
         COMMAND ${PYTHON} -m pip install -r ${SCRIPTS_DIR}/py/requirements.txt
         RESULT_VARIABLE return_code
     )
     if (NOT return_code EQUAL "0")
-        message(FATAL_ERROR "Failed to setup python3 environment")
+        message(FATAL_ERROR "Failed to install requirements")
     endif ()
 endfunction()
diff --git a/scripts/py/gen_model_cpp.py b/scripts/py/gen_model_cpp.py
index 4843668..c43c93a 100644
--- a/scripts/py/gen_model_cpp.py
+++ b/scripts/py/gen_model_cpp.py
@@ -23,6 +23,7 @@ import os
 from argparse import ArgumentParser
 from pathlib import Path
 from jinja2 import Environment, FileSystemLoader
+import binascii
 
 parser = ArgumentParser()
 
@@ -40,32 +41,32 @@ env = Environment(loader=FileSystemLoader(os.path.join(os.path.dirname(__file__)
                   lstrip_blocks=True)
 
 
-def write_tflite_data(tflite_path):
-    # Extract array elements
+def get_tflite_data(tflite_path: str) -> list:
+    """
+    Reads a binary file and returns a C style array as a
+    list of strings.
 
-    bytes = model_hex_bytes(tflite_path)
-    line = '{\n'
-    i = 1
-    while True:
-        try:
-            el = next(bytes)
-            line = line + el + ', '
-            if i % 20 == 0:
-                yield line
-                line = ''
-            i += 1
-        except StopIteration:
-            line = line[:-2] + '};\n'
-            yield line
-            break
+    Argument:
+        tflite_path:    path to the tflite model.
 
-
-def model_hex_bytes(tflite_path):
+    Returns:
+        list of strings
+    """
     with open(tflite_path, 'rb') as tflite_model:
-        byte = tflite_model.read(1)
-        while byte != b"":
-            yield f'0x{byte.hex()}'
-            byte = tflite_model.read(1)
+        data = tflite_model.read()
+
+    bytes_per_line = 32
+    hex_digits_per_line = bytes_per_line * 2
+    hexstream = binascii.hexlify(data).decode('utf-8')
+    hexstring = '{'
+
+    for i in range(0, len(hexstream), 2):
+        if 0 == (i % hex_digits_per_line):
+            hexstring += "\n"
+        hexstring += '0x' + hexstream[i:i+2] + ", "
+
+    hexstring += '};\n'
+    return [hexstring]
 
 
 def main(args):
@@ -87,7 +88,7 @@ def main(args):
                                  year=datetime.datetime.now().year)
 
     env.get_template('tflite.cc.template').stream(common_template_header=hdr,
-                                                  model_data=write_tflite_data(args.tflite_path),
+                                                  model_data=get_tflite_data(args.tflite_path),
                                                   expressions=args.expr,
                                                   additional_headers=args.headers,
                                                   namespaces=args.namespaces).dump(str(cpp_filename))