utils: libtuning: generators: Add raspberrypi output

Add a generator to libtuning for writing tuning output to a json file
formatted the same way that raspberrypi's ctt formats them.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

utils/tuning/libtuning/generators/__init__.py

@@ -1,3 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 #
 # Copyright (C) 2022, Paul Elder <paul.elder@ideasonboard.com>
+
+from libtuning.generators.raspberrypi_output import RaspberryPiOutput

utils/tuning/libtuning/generators/raspberrypi_output.py

@@ -0,0 +1,114 @@
+# SPDX-License-Identifier: BSD-2-Clause
+#
+# Copyright 2022 Raspberry Pi Ltd
+#
+# raspberrypi_output.py - Generate tuning file in Raspberry Pi's json format
+#
+# (Copied from ctt_pretty_print_json.py)
+
+from .generator import Generator
+
+import json
+from pathlib import Path
+import textwrap
+
+
+class Encoder(json.JSONEncoder):
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.indentation_level = 0
+        self.hard_break = 120
+        self.custom_elems = {
+            'table': 16,
+            'luminance_lut': 16,
+            'ct_curve': 3,
+            'ccm': 3,
+            'gamma_curve': 2,
+            'y_target': 2,
+            'prior': 2
+        }
+
+    def encode(self, o, node_key=None):
+        if isinstance(o, (list, tuple)):
+            # Check if we are a flat list of numbers.
+            if not any(isinstance(el, (list, tuple, dict)) for el in o):
+                s = ', '.join(json.dumps(el) for el in o)
+                if node_key in self.custom_elems.keys():
+                    # Special case handling to specify number of elements in a row for tables, ccm, etc.
+                    self.indentation_level += 1
+                    sl = s.split(', ')
+                    num = self.custom_elems[node_key]
+                    chunk = [self.indent_str + ', '.join(sl[x:x + num]) for x in range(0, len(sl), num)]
+                    t = ',\n'.join(chunk)
+                    self.indentation_level -= 1
+                    output = f'\n{self.indent_str}[\n{t}\n{self.indent_str}]'
+                elif len(s) > self.hard_break - len(self.indent_str):
+                    # Break a long list with wraps.
+                    self.indentation_level += 1
+                    t = textwrap.fill(s, self.hard_break, break_long_words=False,
+                                      initial_indent=self.indent_str, subsequent_indent=self.indent_str)
+                    self.indentation_level -= 1
+                    output = f'\n{self.indent_str}[\n{t}\n{self.indent_str}]'
+                else:
+                    # Smaller lists can remain on a single line.
+                    output = f' [ {s} ]'
+                return output
+            else:
+                # Sub-structures in the list case.
+                self.indentation_level += 1
+                output = [self.indent_str + self.encode(el) for el in o]
+                self.indentation_level -= 1
+                output = ',\n'.join(output)
+                return f' [\n{output}\n{self.indent_str}]'
+
+        elif isinstance(o, dict):
+            self.indentation_level += 1
+            output = []
+            for k, v in o.items():
+                if isinstance(v, dict) and len(v) == 0:
+                    # Empty config block special case.
+                    output.append(self.indent_str + f'{json.dumps(k)}: {{ }}')
+                else:
+                    # Only linebreak if the next node is a config block.
+                    sep = f'\n{self.indent_str}' if isinstance(v, dict) else ''
+                    output.append(self.indent_str + f'{json.dumps(k)}:{sep}{self.encode(v, k)}')
+            output = ',\n'.join(output)
+            self.indentation_level -= 1
+            return f'{{\n{output}\n{self.indent_str}}}'
+
+        else:
+            return ' ' + json.dumps(o)
+
+    @property
+    def indent_str(self) -> str:
+        return ' ' * self.indentation_level * self.indent
+
+    def iterencode(self, o, **kwargs):
+        return self.encode(o)
+
+
+class RaspberryPiOutput(Generator):
+    def __init__(self):
+        super().__init__()
+
+    def _pretty_print(self, in_json: dict) -> str:
+
+        if 'version' not in in_json or \
+           'target' not in in_json or \
+           'algorithms' not in in_json or \
+           in_json['version'] < 2.0:
+            raise RuntimeError('Incompatible JSON dictionary has been provided')
+
+        return json.dumps(in_json, cls=Encoder, indent=4, sort_keys=False)
+
+    def write(self, output_file: Path, output_dict: dict, output_order: list):
+        # Write json dictionary to file using ctt's version 2 format
+        out_json = {
+            "version": 2.0,
+            'target': 'bcm2835',
+            "algorithms": [{f'{module.out_name}': output_dict[module]} for module in output_order]
+        }
+
+        with open(output_file, 'w') as f:
+            f.write(self._pretty_print(out_json))