35 lines
1.2 KiB
Python
35 lines
1.2 KiB
Python
# Copyright 2020 The Pigweed Authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may not
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# use this file except in compliance with the License. You may obtain a copy of
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# the License at
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#
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# https://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations under
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# the License.
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"""This module defines the string to ID hash used in pw_rpc."""
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HASH_CONSTANT = 65599
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# This is the same hash function that is used in pw_tokenizer, with the maximum
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# length removed. It is chosen due to its simplicity. The tokenizer code is
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# duplicated here to avoid unnecessary dependencies between modules.
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def hash_65599(string: str) -> int:
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hash_value = len(string)
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coefficient = HASH_CONSTANT
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for char in string:
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hash_value = (hash_value + coefficient * ord(char)) % 2**32
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coefficient = (coefficient * HASH_CONSTANT) % 2**32
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return hash_value
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# Function that converts a name to an ID.
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calculate = hash_65599
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