CU:8693yammy | NiFi scripts: Added Cerner blob decompression util.

nifi/user-scripts/utils/cerner_blob.py

@@ -0,0 +1,124 @@
+from typing import List
+
+
+class LzwItem:
+    def __init__(self, _prefix: int = 0, _suffix: int = 0) -> None:
+        self.prefix = _prefix
+        self.suffix = _suffix
+
+
+class DecompressLzwCernerBlob:
+    def __init__(self) -> None:
+        self.MAX_CODES: int = 8192
+        self.tmp_decompression_buffer: List[int] = [0] * self.MAX_CODES
+        self.lzw_lookup_table: List[LzwItem] = [LzwItem()] * self.MAX_CODES
+        self.tmp_buffer_index: int = 0
+        self.current_byte_buffer_index: int = 0
+
+        # starts after 256, since 256 is the ASCII alphabet
+        self.code_count: int = 257
+        self.output_stream = bytearray()
+
+    def save_to_lookup_table(self, compressed_code: int):
+        self.tmp_buffer_index = -1
+        while compressed_code >= 258:
+            self.tmp_decompression_buffer[self.tmp_buffer_index] = \
+                self.lzw_lookup_table[compressed_code].suffix
+            compressed_code = self.lzw_lookup_table[compressed_code].prefix
+
+        self.tmp_buffer_index += 1
+        self.tmp_decompression_buffer[self.tmp_buffer_index] = compressed_code
+
+        for i in reversed(list(range(self.tmp_buffer_index + 1))):
+            self.output_stream.append(self.tmp_decompression_buffer[i])
+
+    def decompress(self, input_stream=bytearray()):
+
+        byte_buffer_index: int = 0
+
+        # used for bit shifts
+        shift: int = 1
+        current_shift: int = 1
+
+        previous_code: int = 0
+        middle_code: int = 0
+        lookup_index: int = 0
+
+        skip_flag: bool = False
+
+        first_code = input_stream[byte_buffer_index]
+
+        while True:
+            if current_shift >= 9:
+
+                current_shift -= 8
+
+                if first_code != 0:
+                    byte_buffer_index += 1
+                    middle_code = input_stream[byte_buffer_index]
+
+                    first_code = (first_code << current_shift +
+                                  8) | (middle_code << current_shift)
+
+                    byte_buffer_index += 1
+                    middle_code = input_stream[byte_buffer_index]
+
+                    tmp_code = middle_code >> (8 - current_shift)
+                    lookup_index = first_code | tmp_code
+
+                    skip_flag = True
+                else:
+                    byte_buffer_index += 1
+                    first_code = input_stream[byte_buffer_index]
+                    byte_buffer_index += 1
+                    middle_code = input_stream[byte_buffer_index]
+            else:
+                byte_buffer_index += 1
+                middle_code = input_stream[byte_buffer_index]
+
+            if not skip_flag:
+                lookup_index = (first_code << current_shift) | (
+                    middle_code >> 8 - current_shift)
+
+                if lookup_index == 256:
+                    shift = 1
+                    current_shift += 1
+                    first_code = input_stream[byte_buffer_index]
+
+                    self.tmp_decompression_buffer = [0] * self.MAX_CODES
+                    self.tmp_buffer_index = 0
+
+                    self.lzw_lookup_table = [LzwItem()] * self.MAX_CODES
+                    self.code_count = 257
+                    continue
+
+                elif lookup_index == 257:  # EOF marker
+                    return self.output_stream
+
+            skip_flag = False
+
+            # skipit part
+            if previous_code == 0:
+                self.tmp_decompression_buffer[0] = lookup_index
+            if lookup_index < self.code_count:
+                self.save_to_lookup_table(lookup_index)
+                if self.code_count < self.MAX_CODES:
+                    self.lzw_lookup_table[self.code_count] = LzwItem(
+                        previous_code,
+                        self.tmp_decompression_buffer[self.tmp_buffer_index])
+                    self.code_count += 1
+            else:
+                self.lzw_lookup_table[self.code_count] = LzwItem(
+                    previous_code,
+                    self.tmp_decompression_buffer[self.tmp_buffer_index])
+                self.code_count += 1
+                self.save_to_lookup_table(lookup_index)
+            # end of skipit
+
+            first_code = (middle_code & (0xff >> current_shift))
+            current_shift += shift
+
+            if self.code_count in [511, 1023, 2047, 4095]:
+                shift += 1
+                current_shift += 1
+            previous_code = lookup_index