46 lines
1.3 KiB
Python
46 lines
1.3 KiB
Python
# SPDX-License-Identifier: Apache-2.0
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# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
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"""Math utility functions for vLLM."""
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from bisect import bisect_left
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# Approximate value of 1/ln(2), used for log/exp base conversion
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# Best FP32 approximation: 1.4426950216 (hex 0x3FB8AA3B)
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RCP_LN2 = 1.4426950216
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def cdiv(a: int, b: int) -> int:
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"""Ceiling division."""
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return -(a // -b)
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def next_power_of_2(n: int) -> int:
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"""The next power of 2 (inclusive)."""
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return 1 if n < 1 else 1 << (n - 1).bit_length()
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def prev_power_of_2(n: int) -> int:
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"""The previous power of 2 (inclusive)."""
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return 0 if n < 1 else 1 << (n.bit_length() - 1)
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def round_up(x: int, y: int) -> int:
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"""Round up x to the nearest multiple of y."""
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return ((x + y - 1) // y) * y
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def round_down(x: int, y: int) -> int:
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"""Round down x to the nearest multiple of y."""
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return (x // y) * y
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def largest_power_of_2_divisor(n: int) -> int:
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"""Return the largest power-of-2 that divides *n* (isolate lowest set bit)."""
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return n & (-n)
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def round_up_to(values: list[int], n: int) -> int | None:
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"""Round `n` up to the smallest member of sorted `values` >= n, or None."""
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i = bisect_left(values, n)
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return values[i] if i < len(values) else None
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