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37 lines
1.0 KiB
C
37 lines
1.0 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Utility routines.
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*
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* Copyright (C) 2008 Denys Vlasenko
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*
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* Licensed under GPLv2, see file LICENSE in this tarball for details.
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*/
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#include "libbb.h"
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/* Resize (grow) malloced vector.
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*
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* #define magic packed two parameters into one:
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* sizeof = sizeof_and_shift >> 8
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* shift = (sizeof_and_shift) & 0xff
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* (TODO: encode "I want it zeroed" in lowest bit?)
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*
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* Lets say shift = 4. 1 << 4 == 0x10.
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* If idx == 0, 0x10, 0x20 etc, vector[] is resized to next higher
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* idx step, plus one: if idx == 0x20, vector[] is resized to 0x31,
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* thus last usable element is vector[0x30].
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*
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* In other words: after xrealloc_vector(v, 4, idx) it's ok to use
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* at least v[idx] and v[idx+1], for all idx values.
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*/
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void* FAST_FUNC xrealloc_vector_helper(void *vector, unsigned sizeof_and_shift, int idx)
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{
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int mask = 1 << (uint8_t)sizeof_and_shift;
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if (!(idx & (mask - 1))) {
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sizeof_and_shift >>= 8;
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vector = xrealloc(vector, sizeof_and_shift * (idx + mask + 1));
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}
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return vector;
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}
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