88 lines
4.3 KiB
C
88 lines
4.3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
|
||
│vi: set net ft=c ts=8 sts=2 sw=2 fenc=utf-8 :vi│
|
||
╞══════════════════════════════════════════════════════════════════════════════╡
|
||
│ Copyright 2020 Justine Alexandra Roberts Tunney │
|
||
│ │
|
||
│ This program is free software; you can redistribute it and/or modify │
|
||
│ it under the terms of the GNU General Public License as published by │
|
||
│ the Free Software Foundation; version 2 of the License. │
|
||
│ │
|
||
│ This program is distributed in the hope that it will be useful, but │
|
||
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
|
||
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
|
||
│ General Public License for more details. │
|
||
│ │
|
||
│ You should have received a copy of the GNU General Public License │
|
||
│ along with this program; if not, write to the Free Software │
|
||
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
|
||
│ 02110-1301 USA │
|
||
╚─────────────────────────────────────────────────────────────────────────────*/
|
||
#include "libc/assert.h"
|
||
#include "libc/bits/bits.h"
|
||
#include "libc/bits/weaken.h"
|
||
#include "libc/conv/conv.h"
|
||
#include "libc/macros.h"
|
||
#include "libc/mem/mem.h"
|
||
#include "libc/runtime/runtime.h"
|
||
#include "libc/str/str.h"
|
||
#include "libc/sysv/errfuns.h"
|
||
|
||
#define GUARANTEE_TERMINATOR 1
|
||
#define INITIAL_CAPACITY (32 - GUARANTEE_TERMINATOR)
|
||
|
||
/**
|
||
* Grows array, The Cosmopolitan Way.
|
||
*
|
||
* This function may be called once an array has run out of space. If p
|
||
* is NULL, a new array is allocated; otherwise, the array's made 1.5x
|
||
* bigger. It has been written that this amortizes list appends down to
|
||
* constant-time. Extended memory is zeroed. Growth is monotonic.
|
||
*
|
||
* If p points to to static memory or something on the stack, it'll be
|
||
* converted to dynamic memory automatically. This can make algorithms
|
||
* faster when the average case is a small amount of data. It also means
|
||
* functions using this (and free_s()) won't have a hard-requirement on
|
||
* malloc().
|
||
*
|
||
* Consider trying the higher-level append() and concat() APIs (defined
|
||
* in libc/alg/arraylist.h) as an alternative to directly using grow().
|
||
*
|
||
* @param pp points to pointer holding memory address
|
||
* @param capacity tracks maximum items that can be stored in p
|
||
* can only be 0 if p is NULL (see reallocarray() for non-monotonic)
|
||
* @param itemsize is the sizeof each item
|
||
* @return true on success, or false w/ errno and *p is NOT free()'d
|
||
* @error ENOMEM if realloc() not linked or mmap() failed
|
||
* @note tiny programs might need to explicitly YOINK(realloc)
|
||
* @see test/libc/runtime/grow_test.c
|
||
*/
|
||
bool grow(void *pp, size_t *capacity, size_t itemsize, size_t extra) {
|
||
void **p, *p1, *p2;
|
||
size_t n1, n2; /* item counts */
|
||
size_t t1, t2; /* byte counts */
|
||
extra += GUARANTEE_TERMINATOR; /* p ⊃ p[𝑖]==0 */
|
||
p = (void **)pp;
|
||
assert(itemsize);
|
||
assert((*p && *capacity) || (!*p && !*capacity));
|
||
assert(!isheap(*p) || ((intptr_t)*p & 15) == 0);
|
||
p1 = isheap(*p) ? *p : NULL;
|
||
p2 = NULL;
|
||
n1 = *capacity;
|
||
n2 = (*p ? n1 + (n1 >> 1) : MAX(4, INITIAL_CAPACITY / itemsize)) + extra;
|
||
if (!__builtin_mul_overflow(n1, itemsize, &t1) &&
|
||
!__builtin_mul_overflow(n2, itemsize, &t2)) {
|
||
if (weaken(realloc) && (p2 = weaken(realloc)(p1, ROUNDUP(t2, 32)))) {
|
||
if (!p1 && *p) memcpy(p2, *p, t1);
|
||
memset((char *)p2 + t1, 0, t2 - t1);
|
||
*capacity = n2;
|
||
*p = p2;
|
||
return true;
|
||
} else {
|
||
enomem();
|
||
}
|
||
} else {
|
||
eoverflow();
|
||
}
|
||
return false;
|
||
}
|