leb128.h

/*
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#ifndef LEB128_H
#define LEB128_H

/// Utility function to decode a ULEB128 value.
static uint64_t decodeULEB128(const uint8_t *p, unsigned *n,
                              const uint8_t *end,
                              const char **error) {
  const uint8_t *orig_p = p;
  uint64_t Value = 0;
  unsigned Shift = 0;
  if (error)
    *error = NULL;
  do {
    if (end && p == end) {
      if (error)
        *error = "malformed uleb128, extends past end";
      if (n)
        *n = (unsigned)(p - orig_p);
      return 0;
    }
    uint64_t Slice = *p & 0x7f;
    if (Shift >= 64 || Slice << Shift >> Shift != Slice) {
      if (error)
        *error = "uleb128 too big for uint64";
      if (n)
        *n = (unsigned)(p - orig_p);
      return 0;
    }
    Value += (uint64_t)(*p & 0x7f) << Shift;
    Shift += 7;
  } while (*p++ >= 128);
  if (n)
    *n = (unsigned)(p - orig_p);
  return Value;
}

/// Utility function to decode a SLEB128 value.
static int64_t decodeSLEB128(const uint8_t *p, unsigned *n,
                             const uint8_t *end,
                             const char **error) {
  const uint8_t *orig_p = p;
  int64_t Value = 0;
  unsigned Shift = 0;
  uint8_t Byte;
  do {
    if (end && p == end) {
      if (error)
        *error = "malformed sleb128, extends past end";
      if (n)
        *n = (unsigned)(p - orig_p);
      return 0;
    }
    Byte = *p++;
    Value |= ((int64_t)(Byte & 0x7f) << Shift);
    Shift += 7;
  } while (Byte >= 128);
  // Sign extend negative numbers.
  if (Byte & 0x40)
    Value |= (-1ULL) << Shift;
  if (n)
    *n = (unsigned)(p - orig_p);
  return Value;
}

#endif // LEB128_H