From dbef1173b00f0877a63121c40bf607155ac1e9a7 Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Tue, 8 Jul 2008 20:41:57 +0000 Subject: add xrealloc_vector.c --- libbb/xrealloc_vector.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 libbb/xrealloc_vector.c diff --git a/libbb/xrealloc_vector.c b/libbb/xrealloc_vector.c new file mode 100644 index 000000000..ccc961b7b --- /dev/null +++ b/libbb/xrealloc_vector.c @@ -0,0 +1,36 @@ +/* vi: set sw=4 ts=4: */ +/* + * Utility routines. + * + * Copyright (C) 2008 Denys Vlasenko + * + * Licensed under GPLv2, see file LICENSE in this tarball for details. + */ + +#include "libbb.h" + +/* Resize (grow) malloced vector. + * + * #define magic packed two parameters into one: + * sizeof = sizeof_and_shift >> 8 + * shift = (sizeof_and_shift) & 0xff + * (TODO: encode "I want it zeroed" in lowest bit?) + * + * Lets say shift = 4. 1 << 4 == 0x10. + * If idx == 0, 0x10, 0x20 etc, vector[] is resized to next higher + * idx step, plus one: if idx == 0x20, vector[] is resized to 0x31, + * thus last usable element is vector[0x30]. + * + * In other words: after xrealloc_vector(v, 4, idx) it's ok to use + * at least v[idx] and v[idx+1], for all idx values. + */ +void* FAST_FUNC xrealloc_vector_helper(void *vector, unsigned sizeof_and_shift, int idx) +{ + int mask = 1 << (uint8_t)sizeof_and_shift; + + if (!(idx & (mask - 1))) { + sizeof_and_shift >>= 8; + vector = xrealloc(vector, sizeof_and_shift * (idx + mask + 1)); + } + return vector; +} -- cgit v1.2.3