e23b41e79a
Co-authored-by: Pepijn <138571049+pkooij@users.noreply.github.com> Co-authored-by: Steven Palma <imstevenpmwork@ieee.org> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com> Co-authored-by: Steven Palma <steven.palma@huggingface.co> Co-authored-by: Adil Zouitine <adilzouitinegm@gmail.com> Co-authored-by: Pepijn <pepijn@huggingface.co>
68 lines
2.2 KiB
Python
68 lines
2.2 KiB
Python
# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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def encode_sign_magnitude(value: int, sign_bit_index: int):
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"""
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https://en.wikipedia.org/wiki/Signed_number_representations#Sign%E2%80%93magnitude
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"""
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max_magnitude = (1 << sign_bit_index) - 1
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magnitude = abs(value)
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if magnitude > max_magnitude:
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raise ValueError(f"Magnitude {magnitude} exceeds {max_magnitude} (max for {sign_bit_index=})")
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direction_bit = 1 if value < 0 else 0
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return (direction_bit << sign_bit_index) | magnitude
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def decode_sign_magnitude(encoded_value: int, sign_bit_index: int):
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"""
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https://en.wikipedia.org/wiki/Signed_number_representations#Sign%E2%80%93magnitude
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"""
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direction_bit = (encoded_value >> sign_bit_index) & 1
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magnitude_mask = (1 << sign_bit_index) - 1
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magnitude = encoded_value & magnitude_mask
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return -magnitude if direction_bit else magnitude
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def encode_twos_complement(value: int, n_bytes: int):
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"""
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https://en.wikipedia.org/wiki/Signed_number_representations#Two%27s_complement
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"""
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bit_width = n_bytes * 8
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min_val = -(1 << (bit_width - 1))
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max_val = (1 << (bit_width - 1)) - 1
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if not (min_val <= value <= max_val):
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raise ValueError(
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f"Value {value} out of range for {n_bytes}-byte two's complement: [{min_val}, {max_val}]"
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)
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if value >= 0:
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return value
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return (1 << bit_width) + value
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def decode_twos_complement(value: int, n_bytes: int) -> int:
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"""
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https://en.wikipedia.org/wiki/Signed_number_representations#Two%27s_complement
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"""
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bits = n_bytes * 8
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sign_bit = 1 << (bits - 1)
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if value & sign_bit:
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value -= 1 << bits
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return value
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