32 lines
958 B
C
32 lines
958 B
C
/* SPDX-FileCopyrightText: 2023 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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#pragma once
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/** \file
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* \ingroup bli
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*
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* General looping helpers, use `BLI_FOREACH` prefix.
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*/
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/**
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* Even value distribution.
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*
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* \a src must be larger than \a dst,
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* \a dst defines the number of iterations, their values are evenly spaced.
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*
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* The following pairs represent (src, dst) arguments and the values they loop over.
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* <pre>
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* (19, 4) -> [2, 7, 11. 16]
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* (100, 5) -> [9, 29, 49, 69, 89]
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* (100, 3) -> [16, 49, 83]
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* (100, 100) -> [0..99]
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* </pre>
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* \note this is mainly useful for numbers that might not divide evenly into each other.
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*/
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#define BLI_FOREACH_SPARSE_RANGE(src, dst, i) \
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for (int _src = (src), _src2 = _src * 2, _dst2 = (dst)*2, _error = _dst2 - _src, i = 0, _delta; \
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((void)(_delta = divide_floor_i(_error, _dst2)), (void)(i -= _delta), (i < _src)); \
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_error -= (_delta * _dst2) + _src2)
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