cosmopolitan/libc/stdio/appendw.c
Justine Tunney 8bfd56b59e
Rename _bsr/_bsf to bsr/bsf
Now that these functions are behind _COSMO_SOURCE there's no reason for
having the ugly underscore anymore. To use these functions, you need to
pass -mcosmo to cosmocc.
2024-03-04 17:33:26 -08:00

84 lines
3.3 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/dce.h"
#include "libc/intrin/bsr.h"
#include "libc/macros.internal.h"
#include "libc/mem/mem.h"
#include "libc/serialize.h"
#include "libc/stdio/append.h"
#define W sizeof(size_t)
/**
* Appends character or word-encoded string to buffer.
*
* Up to eight characters can be appended. For example:
*
* appendw(&s, 'h'|'i'<<8);
* appendw(&s, READ64LE("hi\0\0\0\0\0"));
*
* Are equivalent to:
*
* appends(&s, "hi");
*
* The special case:
*
* appendw(&s, 0);
*
* Will append a single NUL character.
*
* This function is slightly faster than appendd() and appends(). Its
* main advantage is it improves code size in functions that call it.
*
* The resulting buffer is guaranteed to be NUL-terminated, i.e.
* `!b[appendz(b).i]` will be the case.
*
* @return bytes appended or -1 if `ENOMEM`
* @see appendz(b).i to get buffer length
*/
ssize_t appendw(char **b, uint64_t w) {
size_t n;
unsigned l;
char *p, *q;
struct appendz z;
z = appendz((p = *b));
l = w ? (bsrl(w) >> 3) + 1 : 1;
n = ROUNDUP(z.i + 8 + 1, 8) + W;
if (n > z.n) {
if (!z.n) z.n = W * 2;
while (n > z.n) z.n += z.n >> 1;
z.n = ROUNDUP(z.n, W);
if ((p = realloc(p, z.n))) {
z.n = malloc_usable_size(p);
unassert(!(z.n & (W - 1)));
*b = p;
} else {
return -1;
}
}
q = p + z.i;
WRITE64LE(q, w);
q[8] = 0;
z.i += l;
if (!IsTiny() && W == 8) z.i |= (size_t)APPEND_COOKIE << 48;
*(size_t *)(p + z.n - W) = z.i;
return l;
}