cosmopolitan/libc/fmt/uleb64.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 2020 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.      │
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│ 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/fmt/leb128.h"

/**
 * Encodes unsigned integer to array.
 *
 *     uleb64 INT64_MAX    l:        10𝑐         3𝑛𝑠
 *     zleb64 INT64_MAX    l:        13𝑐         4𝑛𝑠
 *     sleb64 INT64_MAX    l:        16𝑐         5𝑛𝑠
 *     uleb128 INT64_MAX   l:        18𝑐         6𝑛𝑠
 *     zleb128 INT64_MAX   l:        18𝑐         6𝑛𝑠
 *     sleb128 INT64_MAX   l:        24𝑐         8𝑛𝑠
 *     zleb64 INT64_MIN    l:        13𝑐         4𝑛𝑠
 *     sleb64 INT64_MIN    l:        16𝑐         5𝑛𝑠
 *     zleb128 INT64_MIN   l:        19𝑐         6𝑛𝑠
 *     sleb128 INT64_MIN   l:        24𝑐         8𝑛𝑠
 *
 * @param p is output array
 * @param x is number
 * @return p + i
 */
char *uleb64(char p[hasatleast 10], uint64_t x) {
  int c;
  for (;;) {
    c = x & 127;
    if (!(x >>= 7)) {
      *p++ = c;
      return p;
    } else {
      *p++ = c | 128;
    }
  }
}