vfscanf.c

Newlib 嵌入式 C库 标准实现代码

		case 'B':
		case 'C':
		case 'D':
		case 'E':
		case 'F':
		case 'a':
		case 'b':
		case 'c':
		case 'd':
		case 'e':
		case 'f':
		  /* no need to fix base here */
		  if (base <= 10)
		    break;	/* not legal here */
		  flags &= ~(SIGNOK | PFXOK | NDIGITS | NNZDIGITS);
		  goto ok;

		  /* sign ok only as first character */
		case '+':
		case '-':
		  if (flags & SIGNOK)
		    {
		      flags &= ~SIGNOK;
		      goto ok;
		    }
		  break;

		  /* x ok iff flag still set & single 0 seen */
		case 'x':
		case 'X':
		  if ((flags & (PFXOK | NZDIGITS)) == PFXOK)
		    {
		      base = 16;/* if %i */
		      flags &= ~PFXOK;
		      /* We must reset the NZDIGITS and NDIGITS
			 flags that would have been unset by seeing
			 the zero that preceded the X or x.  */
		      flags |= NZDIGITS | NDIGITS;
		      goto ok;
		    }
		  break;
		}

	      /*
	       * If we got here, c is not a legal character
	       * for a number.  Stop accumulating digits.
	       */
	      break;
	    ok:
	      /*
	       * c is legal: store it and look at the next.
	       */
	      *p++ = c;
	    skip:
	      if (--fp->_r > 0)
		fp->_p++;
	      else
	      if (__srefill_r (rptr, fp))
		break;		/* EOF */
	    }
	  /*
	   * If we had only a sign, it is no good; push back the sign.
	   * If the number ends in `x', it was [sign] '0' 'x', so push back
	   * the x and treat it as [sign] '0'.
	   * Use of ungetc here and below assumes ASCII encoding; we are only
	   * pushing back 7-bit characters, so casting to unsigned char is
	   * not necessary.
	   */
	  if (flags & NDIGITS)
	    {
	      if (p > buf)
		_ungetc_r (rptr, *--p, fp); /* [-+xX] */
	      if (p == buf)
		goto match_failure;
	    }
	  if ((flags & SUPPRESS) == 0)
	    {
	      u_long res;

	      *p = 0;
	      res = (*ccfn) (rptr, buf, (char **) NULL, base);
	      if (flags & POINTER)
		{
		  void **vp = GET_ARG (N, ap, void **);
#ifndef _NO_LONGLONG
		  if (sizeof (uintptr_t) > sizeof (u_long))
		    {
		      u_long_long resll;
		      resll = _strtoull_r (rptr, buf, (char **) NULL, base);
		      *vp = (void *) (uintptr_t) resll;
		    }
		  else
#endif /* !_NO_LONGLONG */
		    *vp = (void *) (uintptr_t) res;
		}
#ifdef _WANT_IO_C99_FORMATS
	      else if (flags & CHAR)
		{
		  cp = GET_ARG (N, ap, char *);
		  *cp = res;
		}
#endif
	      else if (flags & SHORT)
		{
		  sp = GET_ARG (N, ap, short *);
		  *sp = res;
		}
	      else if (flags & LONG)
		{
		  lp = GET_ARG (N, ap, long *);
		  *lp = res;
		}
#ifndef _NO_LONGLONG
	      else if (flags & LONGDBL)
		{
		  u_long_long resll;
		  if (ccfn == _strtoul_r)
		    resll = _strtoull_r (rptr, buf, (char **) NULL, base);
		  else
		    resll = _strtoll_r (rptr, buf, (char **) NULL, base);
		  llp = GET_ARG (N, ap, long long*);
		  *llp = resll;
		}
#endif
	      else
		{
		  ip = GET_ARG (N, ap, int *);
		  *ip = res;
		}
	      nassigned++;
	    }
	  nread += p - buf + skips;
	  break;
	}
#ifdef FLOATING_POINT
	case CT_FLOAT:
	{
	  /* scan a floating point number as if by strtod */
	  /* This code used to assume that the number of digits is reasonable.
	     However, ANSI / ISO C makes no such stipulation; we have to get
	     exact results even when there is an unreasonable amount of
	     leading zeroes.  */
	  long leading_zeroes = 0;
	  long zeroes, exp_adjust;
	  char *exp_start = NULL;
	  unsigned width_left = 0;
	  char nancount = 0;
	  char infcount = 0;
#ifdef hardway
	  if (width == 0 || width > sizeof (buf) - 1)
#else
	  /* size_t is unsigned, hence this optimisation */
	  if (width - 1 > sizeof (buf) - 2)
#endif
	    {
	      width_left = width - (sizeof (buf) - 1);
	      width = sizeof (buf) - 1;
	    }
	  flags |= SIGNOK | NDIGITS | DPTOK | EXPOK;
	  zeroes = 0;
	  exp_adjust = 0;
	  for (p = buf; width; )
	    {
	      c = *fp->_p;
	      /*
	       * This code mimicks the integer conversion
	       * code, but is much simpler.
	       */
	      switch (c)
		{
		case '0':
		  if (flags & NDIGITS)
		    {
		      flags &= ~SIGNOK;
		      zeroes++;
		      if (width_left)
			{
			  width_left--;
			  width++;
			}
		      goto fskip;
		    }
		  /* Fall through.  */
		case '1':
		case '2':
		case '3':
		case '4':
		case '5':
		case '6':
		case '7':
		case '8':
		case '9':
		  if (nancount + infcount == 0)
		    {
		      flags &= ~(SIGNOK | NDIGITS);
		      goto fok;
		    }
		  break;

		case '+':
		case '-':
		  if (flags & SIGNOK)
		    {
		      flags &= ~SIGNOK;
		      goto fok;
		    }
		  break;
		case 'n':
		case 'N':
		  if (nancount == 0
		      && (flags & (NDIGITS | DPTOK | EXPOK)) ==
				  (NDIGITS | DPTOK | EXPOK))
		    {
		      flags &= ~(SIGNOK | DPTOK | EXPOK | NDIGITS);
		      nancount = 1;
		      goto fok;
		    }
		  if (nancount == 2)
		    {
		      nancount = 3;
		      goto fok;
		    }
		  if (infcount == 1 || infcount == 4)
		    {
		      infcount++;
		      goto fok;
		    }
		  break;
		case 'a':
		case 'A':
		  if (nancount == 1)
		    {
		      nancount = 2;
		      goto fok;
		    }
		  break;
		case 'i':
		case 'I':
		  if (infcount == 0
		      && (flags & (NDIGITS | DPTOK | EXPOK)) ==
				  (NDIGITS | DPTOK | EXPOK))
		    {
		      flags &= ~(SIGNOK | DPTOK | EXPOK | NDIGITS);
		      infcount = 1;
		      goto fok;
		    }
		  if (infcount == 3 || infcount == 5)
		    {
		      infcount++;
		      goto fok;
		    }
		  break;
		case 'f':
		case 'F':
		  if (infcount == 2)
		    {
		      infcount = 3;
		      goto fok;
		    }
		  break;
		case 't':
		case 'T':
		  if (infcount == 6)
		    {
		      infcount = 7;
		      goto fok;
		    }
		  break;
		case 'y':
		case 'Y':
		  if (infcount == 7)
		    {
		      infcount = 8;
		      goto fok;
		    }
		  break;
		case '.':
		  if (flags & DPTOK)
		    {
		      flags &= ~(SIGNOK | DPTOK);
		      leading_zeroes = zeroes;
		      goto fok;
		    }
		  break;
		case 'e':
		case 'E':
		  /* no exponent without some digits */
		  if ((flags & (NDIGITS | EXPOK)) == EXPOK
		      || ((flags & EXPOK) && zeroes))
		    {
		      if (! (flags & DPTOK))
			{
			  exp_adjust = zeroes - leading_zeroes;
			  exp_start = p;
			}
		      flags =
			(flags & ~(EXPOK | DPTOK)) |
			SIGNOK | NDIGITS;
		      zeroes = 0;
		      goto fok;
		    }
		  break;
		}
	      break;
	    fok:
	      *p++ = c;
	    fskip:
	      width--;
	      ++nread;
	      if (--fp->_r > 0)
		fp->_p++;
	      else
	      if (__srefill_r (rptr, fp))
		break;		/* EOF */
	    }
	  if (zeroes)
	    flags &= ~NDIGITS;
	  /* We may have a 'N' or possibly even [sign] 'N' 'a' as the
	     start of 'NaN', only to run out of chars before it was
	     complete (or having encountered a non-matching char).  So
	     check here if we have an outstanding nancount, and if so
	     put back the chars we did swallow and treat as a failed
	     match.

	     FIXME - we still don't handle NAN([0xdigits]).  */
	  if (nancount - 1U < 2U) /* nancount && nancount < 3 */
	    {
	      /* Newlib's ungetc works even if we called __srefill in
		 the middle of a partial parse, but POSIX does not
		 guarantee that in all implementations of ungetc.  */
	      while (p > buf)
		{
		  _ungetc_r (rptr, *--p, fp); /* [-+nNaA] */
		  --nread;
		}
	      goto match_failure;
	    }
	  /* Likewise for 'inf' and 'infinity'.	 But be careful that
	     'infinite' consumes only 3 characters, leaving the stream
	     at the second 'i'.	 */
	  if (infcount - 1U < 7U) /* infcount && infcount < 8 */
	    {
	      if (infcount >= 3) /* valid 'inf', but short of 'infinity' */
		while (infcount-- > 3)
		  {
		    _ungetc_r (rptr, *--p, fp); /* [iInNtT] */
		    --nread;
		  }
	      else
		{
		  while (p > buf)
		    {
		      _ungetc_r (rptr, *--p, fp); /* [-+iInN] */
		      --nread;
		    }
		  goto match_failure;
		}
	    }
	  /*
	   * If no digits, might be missing exponent digits
	   * (just give back the exponent) or might be missing
	   * regular digits, but had sign and/or decimal point.
	   */
	  if (flags & NDIGITS)
	    {
	      if (flags & EXPOK)
		{
		  /* no digits at all */
		  while (p > buf)
		    {
		      _ungetc_r (rptr, *--p, fp); /* [-+.] */
		      --nread;
		    }
		  goto match_failure;
		}
	      /* just a bad exponent (e and maybe sign) */
	      c = *--p;
	      --nread;
	      if (c != 'e' && c != 'E')
		{
		  _ungetc_r (rptr, c, fp); /* [-+] */
		  c = *--p;
		  --nread;
		}
	      _ungetc_r (rptr, c, fp); /* [eE] */
	    }
	  if ((flags & SUPPRESS) == 0)
	    {
	      double res = 0;
#ifdef _NO_LONGDBL
#define QUAD_RES res;
#else  /* !_NO_LONG_DBL */
	      long double qres = 0;
#define QUAD_RES qres;
#endif /* !_NO_LONG_DBL */
	      long new_exp = 0;

	      *p = 0;
	      if ((flags & (DPTOK | EXPOK)) == EXPOK)
		{
		  exp_adjust = zeroes - leading_zeroes;
		  new_exp = -exp_adjust;
		  exp_start = p;
		}
	      else if (exp_adjust)
                new_exp = _strtol_r (rptr, (exp_start + 1), NULL, 10) - exp_adjust;
	      if (exp_adjust)
		{

		  /* If there might not be enough space for the new exponent,
		     truncate some trailing digits to make room.  */
		  if (exp_start >= buf + sizeof (buf) - MAX_LONG_LEN)
		    exp_start = buf + sizeof (buf) - MAX_LONG_LEN - 1;
                 sprintf (exp_start, "e%ld", new_exp);
		}

	      /* Current _strtold routine is markedly slower than 
	         _strtod_r.  Only use it if we have a long double
	         result.  */
#ifndef _NO_LONGDBL /* !_NO_LONGDBL */
	      if (flags & LONGDBL)
		qres = _strtold (buf, NULL);
	      else
#endif
	        res = _strtod_r (rptr, buf, NULL);

	      if (flags & LONG)
		{
		  dp = GET_ARG (N, ap, double *);
		  *dp = res;
		}
	      else if (flags & LONGDBL)
		{
		  ldp = GET_ARG (N, ap, _LONG_DOUBLE *);
		  *ldp = QUAD_RES;
		}
	      else
		{
		  flp = GET_ARG (N, ap, float *);
		  if (isnan (res))
		    *flp = nanf (NULL);
		  else
		    *flp = res;
		}
	      nassigned++;
	    }
	  break;
	}
#endif /* FLOATING_POINT */
	}
    }
input_failure:
  /* On read failure, return EOF failure regardless of matches; errno
     should have been set prior to here.  On EOF failure (including
     invalid format string), return EOF if no matches yet, else number
     of matches made prior to failure.  */
  _funlockfile (fp);
  return nassigned && !(fp->_flags & __SERR) ? nassigned : EOF;
match_failure:
all_done:
  /* Return number of matches, which can be 0 on match failure.  */
  _funlockfile (fp);
  return nassigned;
}

#ifndef _NO_POS_ARGS
/* Process all intermediate arguments.  Fortunately, with scanf, all
   intermediate arguments are sizeof(void*), so we don't need to scan
   ahead in the format string.  */
static void *
get_arg (int n, va_list *ap, int *numargs_p, void **args)
{
  int numargs = *numargs_p;
  while (n >= numargs)
    args[numargs++] = va_arg (*ap, void *);
  *numargs_p = numargs;
  return args[n];
}
#endif /* !_NO_POS_ARGS */