/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-â
âvi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :viâ
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ¡
â Copyright 2020 Justine Alexandra Roberts Tunney                              â
â                                                                              â
â Permission to use, copy, modify, and/or distribute this software for         â
â any purpose with or without fee is hereby granted, provided that the         â
â above copyright notice and this permission notice appear in all copies.      â
â                                                                              â
â THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                â
â WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                â
â WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             â
â AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         â
â DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        â
â PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               â
â TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             â
â PERFORMANCE OF THIS SOFTWARE.                                                â
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ
                             â             âââ
                       ââââââââ     â     ââââââââââ
                â    ââââ  âââ    ââââââ    âââââââ         âââ
            ââââââ   ââââ   ââââ           ââââââ         âââââââ
             ââââââ  âââââ  ââââ         âââââââââââ    ââââââââ
      ââââ      ââââ   ââââââââ                ââââ âââââââââââ   ââââââââ
   âââââââ    â   âââââ   ââ                          âââ âââââ  âââââââââââ
  ââââ ââââ  âââ  âââ                                     âââââ âââââ    âââââ
   ââ  âââââââââ        VARIABLE LENGTH INTEGER ENCODING        âââ  âââ â  â
       ââââââ                                                    ââââââââ
        âââ                                                         */
#include "libc/fmt/leb128.h"

/**
 * Encodes signed integer to array w/ zig-zag encoding.
 *
 *     uleb64 INT64_MAX    l:        10ð         3ðð 
 *     zleb64 INT64_MAX    l:        13ð         4ðð 
 *     sleb64 INT64_MAX    l:        16ð         5ðð 
 *     uleb128 INT64_MAX   l:        18ð         6ðð 
 *     zleb128 INT64_MAX   l:        18ð         6ðð 
 *     sleb128 INT64_MAX   l:        24ð         8ðð 
 *
 * @param p is output array which should have 10 items
 * @param x is number
 * @return p + i
 * @see unzleb64()
 */
char *zleb64(char p[hasatleast 10], int64_t x) {
  int c;
  uint64_t u;
  u = x;
  u <<= 1;
  u ^= x >> 63;
  for (;;) {
    c = u & 127;
    if (!(u >>= 7)) {
      *p++ = c;
      return p;
    } else {
      *p++ = c | 128;
    }
  }
}
