ldtoa.c

用于嵌入式Linux系统的标准C的库函数

/* Mode 3 is "f" format.  */
if( mode != 3 )
        ndigits -= 1;
/* Mode 0 is for %.999 format, which is supposed to give a
   minimum length string that will convert back to the same binary value.
   For now, just ask for 20 digits which is enough but sometimes too many.  */
if( mode == 0 )
        ndigits = 20;

/* This sanity limit must agree with the corresponding one in etoasc, to
   keep straight the returned value of outexpon.  */
if( ndigits > NDEC )
        ndigits = NDEC;

etoasc( e, outbuf, ndigits, mode, ldp );
s =  outbuf;
if( eisinf(e) || eisnan(e) )
        {
        *decpt = 9999;
        goto stripspaces;
        }
*decpt = ldp->outexpon + 1;

/* Transform the string returned by etoasc into what the caller wants.  */

/* Look for decimal point and delete it from the string. */
s = outbuf;
while( *s != '\0' )
        {
        if( *s == '.' )
               goto yesdecpt;
        ++s;
        }
goto nodecpt;

yesdecpt:

/* Delete the decimal point.  */
while( *s != '\0' )
        {
        *s = *(s+1);
        ++s;
        }

nodecpt:

/* Back up over the exponent field. */
while( *s != 'E' && s > outbuf)
        --s;
*s = '\0';

stripspaces:

/* Strip leading spaces and sign. */
p = outbuf;
while( *p == ' ' || *p == '-')
        ++p;

/* Find new end of string.  */
s = outbuf;
while( (*s++ = *p++) != '\0' )
        ;
--s;

/* Strip trailing zeros.  */
if( mode == 2 )
        k = 1;
else if( ndigits > ldp->outexpon )
        k = ndigits;
else
        k = ldp->outexpon;

while( *(s-1) == '0' && ((s - outbuf) > k))
        *(--s) = '\0';

/* In f format, flush small off-scale values to zero.
   Rounding has been taken care of by etoasc. */
if( mode == 3 && ((ndigits + ldp->outexpon) < 0))
        {
        s = outbuf;
        *s = '\0';
        *decpt = 0;
        }

/* reentrancy addition to use mprec storage pool */
/* we want to have enough space to hold the formatted result */

if (mode == 3) /* f format, account for sign + dec digits + decpt + frac */
  i = *decpt + orig_ndigits + 3;
else /* account for sign + max precision digs + E + exp sign + exponent */
  i = orig_ndigits + MAX_EXP_DIGITS + 4;

j = sizeof (__ULong);
for (_REENT_MP_RESULT_K(ptr) = 0; sizeof (_Bigint) - sizeof (__ULong) + j <= i; j <<= 1)
  _REENT_MP_RESULT_K(ptr)++;
_REENT_MP_RESULT(ptr) = Balloc (ptr, _REENT_MP_RESULT_K(ptr));

/* Copy from internal temporary buffer to permanent buffer.  */
outstr = (char *)_REENT_MP_RESULT(ptr);
strcpy (outstr, outbuf);

if( rve )
        *rve = outstr + (s - outbuf);

return outstr;
}

/* Routine used to tell if long double is NaN or Infinity or regular number. 
   Returns:  0 = regular number
             1 = Nan
             2 = Infinity
*/
int
_ldcheck (long double *d)
{
unsigned short e[NI];
LDPARMS rnd;
LDPARMS *ldp = &rnd;

rnd.rlast = -1;
rnd.rndprc = NBITS;

#if LDBL_MANT_DIG == 24
e24toe( (unsigned short *)d, e, ldp );
#elif LDBL_MANT_DIG == 53
e53toe( (unsigned short *)d, e, ldp );
#elif LDBL_MANT_DIG == 64
e64toe( (unsigned short *)d, e, ldp );
#else
e113toe( (unsigned short *)d, e, ldp );
#endif

if( (e[NE-1] & 0x7fff) == 0x7fff )
	{
#ifdef NANS
	if( eisnan(e) )
		return( 1 );
#endif
	return( 2 );
	}
else
	return( 0 );
} /* _ldcheck */

static void etoasc(short unsigned int *x, char *string, int ndigits, int outformat, LDPARMS *ldp)
{
long digit;
unsigned short y[NI], t[NI], u[NI], w[NI];
unsigned short *p, *r, *ten;
unsigned short sign;
int i, j, k, expon, rndsav, ndigs;
char *s, *ss;
unsigned short m;
unsigned short *equot = ldp->equot;

ndigs = ndigits;
rndsav = ldp->rndprc;
#ifdef NANS
if( eisnan(x) )
	{
	sprintf( string, " NaN " );
	expon = 9999;
	goto bxit;
	}
#endif
ldp->rndprc = NBITS;		/* set to full precision */
emov( x, y ); /* retain external format */
if( y[NE-1] & 0x8000 )
	{
	sign = 0xffff;
	y[NE-1] &= 0x7fff;
	}
else
	{
	sign = 0;
	}
expon = 0;
ten = &etens[NTEN][0];
emov( eone, t );
/* Test for zero exponent */
if( y[NE-1] == 0 )
	{
	for( k=0; k<NE-1; k++ )
		{
		if( y[k] != 0 )
			goto tnzro; /* denormalized number */
		}
	goto isone; /* legal all zeros */
	}
tnzro:

/* Test for infinity.
 */
if( y[NE-1] == 0x7fff )
	{
	if( sign )
		sprintf( string, " -Infinity " );
	else
		sprintf( string, " Infinity " );
	expon = 9999;
	goto bxit;
	}

/* Test for exponent nonzero but significand denormalized.
 * This is an error condition.
 */
if( (y[NE-1] != 0) && ((y[NE-2] & 0x8000) == 0) )
	{
	mtherr( "etoasc", DOMAIN );
	sprintf( string, "NaN" );
	expon = 9999;
	goto bxit;
	}

/* Compare to 1.0 */
i = ecmp( eone, y );
if( i == 0 )
	goto isone;

if( i < 0 )
	{ /* Number is greater than 1 */
/* Convert significand to an integer and strip trailing decimal zeros. */
	emov( y, u );
	u[NE-1] = EXONE + NBITS - 1;

	p = &etens[NTEN-4][0];
	m = 16;
do
	{
	ediv( p, u, t, ldp );
	efloor( t, w, ldp );
	for( j=0; j<NE-1; j++ )
		{
		if( t[j] != w[j] )
			goto noint;
		}
	emov( t, u );
	expon += (int )m;
noint:
	p += NE;
	m >>= 1;
	}
while( m != 0 );

/* Rescale from integer significand */
	u[NE-1] += y[NE-1] - (unsigned int )(EXONE + NBITS - 1);
	emov( u, y );
/* Find power of 10 */
	emov( eone, t );
	m = MAXP;
	p = &etens[0][0];
	while( ecmp( ten, u ) <= 0 )
		{
		if( ecmp( p, u ) <= 0 )
			{
			ediv( p, u, u, ldp );
			emul( p, t, t, ldp );
			expon += (int )m;
			}
		m >>= 1;
		if( m == 0 )
			break;
		p += NE;
		}
	}
else
	{ /* Number is less than 1.0 */
/* Pad significand with trailing decimal zeros. */
	if( y[NE-1] == 0 )
		{
		while( (y[NE-2] & 0x8000) == 0 )
			{
			emul( ten, y, y, ldp );
			expon -= 1;
			}
		}
	else
		{
		emovi( y, w );
		for( i=0; i<NDEC+1; i++ )
			{
			if( (w[NI-1] & 0x7) != 0 )
				break;
/* multiply by 10 */
			emovz( w, u );
			eshdn1( u );
			eshdn1( u );
			eaddm( w, u );
			u[1] += 3;
			while( u[2] != 0 )
				{
				eshdn1(u);
				u[1] += 1;
				}
			if( u[NI-1] != 0 )
				break;
			if( eone[NE-1] <= u[1] )
				break;
			emovz( u, w );
			expon -= 1;
			}
		emovo( w, y, ldp );
		}
	k = -MAXP;
	p = &emtens[0][0];
	r = &etens[0][0];
	emov( y, w );
	emov( eone, t );
	while( ecmp( eone, w ) > 0 )
		{
		if( ecmp( p, w ) >= 0 )
			{
			emul( r, w, w, ldp );
			emul( r, t, t, ldp );
			expon += k;
			}
		k /= 2;
		if( k == 0 )
			break;
		p += NE;
		r += NE;
		}
	ediv( t, eone, t, ldp );
	}
isone:
/* Find the first (leading) digit. */
emovi( t, w );
emovz( w, t );
emovi( y, w );
emovz( w, y );
eiremain( t, y, ldp );
digit = equot[NI-1];
while( (digit == 0) && (ecmp(y,ezero) != 0) )
	{
	eshup1( y );
	emovz( y, u );
	eshup1( u );
	eshup1( u );
	eaddm( u, y );
	eiremain( t, y, ldp );
	digit = equot[NI-1];
	expon -= 1;
	}
s = string;
if( sign )
	*s++ = '-';
else
	*s++ = ' ';
/* Examine number of digits requested by caller. */
if( outformat == 3 )
        ndigs += expon;
/*
else if( ndigs < 0 )
        ndigs = 0;
*/
if( ndigs > NDEC )
	ndigs = NDEC;
if( digit == 10 )
	{
	*s++ = '1';
	*s++ = '.';
	if( ndigs > 0 )
		{
		*s++ = '0';
		ndigs -= 1;
		}
	expon += 1;
	if( ndigs < 0 )
	        {
	        ss = s;
	        goto doexp;
	        }
	}
else
	{
	*s++ = (char )digit + '0';
	*s++ = '.';
	}
/* Generate digits after the decimal point. */
for( k=0; k<=ndigs; k++ )
	{
/* multiply current number by 10, without normalizing */
	eshup1( y );
	emovz( y, u );
	eshup1( u );
	eshup1( u );
	eaddm( u, y );
	eiremain( t, y, ldp );
	*s++ = (char )equot[NI-1] + '0';
	}
digit = equot[NI-1];
--s;
ss = s;
/* round off the ASCII string */
if( digit > 4 )
	{
/* Test for critical rounding case in ASCII output. */
	if( digit == 5 )
		{
		emovo( y, t, ldp );
		if( ecmp(t,ezero) != 0 )
			goto roun;	/* round to nearest */
		if( (*(s-1) & 1) == 0 )
			goto doexp;	/* round to even */
		}
/* Round up and propagate carry-outs */
roun:
	--s;
	k = *s & 0x7f;
/* Carry out to most significant digit? */
	if( ndigs < 0 )
		{
	        /* This will print like "1E-6". */
		*s = '1';
		expon += 1;
		goto doexp;
		}
	else if( k == '.' )
		{
		--s;
		k = *s;
		k += 1;
		*s = (char )k;
/* Most significant digit carries to 10? */
		if( k > '9' )
			{
			expon += 1;
			*s = '1';
			}
		goto doexp;
		}
/* Round up and carry out from less significant digits */
	k += 1;
	*s = (char )k;
	if( k > '9' )
		{
		*s = '0';
		goto roun;
		}
	}
doexp:
#ifdef __GO32__
if( expon >= 0 )
	sprintf( ss, "e+%02d", expon );
else
	sprintf( ss, "e-%02d", -expon );
#else
	sprintf( ss, "E%d", expon );
#endif
bxit:
ldp->rndprc = rndsav;
ldp->outexpon =  expon;
}




/*
;								ASCTOQ
;		ASCTOQ.MAC		LATEST REV: 11 JAN 84
;					SLM, 3 JAN 78
;
;	Convert ASCII string to quadruple precision floating point
;
;		Numeric input is free field decimal number
;		with max of 15 digits with or without 
;		decimal point entered as ASCII from teletype.
;	Entering E after the number followed by a second
;	number causes the second number to be interpreted
;	as a power of 10 to be multiplied by the first number
;	(i.e., "scientific" notation).
;
;	Usage:
;		asctoq( string, q );
*/

long double _strtold (char *s, char **se)
{
  long double x;
  LDPARMS rnd;
  LDPARMS *ldp = &rnd;
  int lenldstr;

  rnd.rlast = -1;
  rnd.rndprc = NBITS;

  lenldstr = asctoeg( s, (unsigned short *)&x, LDBL_MANT_DIG, ldp );
  if (se)
    *se = s + lenldstr;
  return x;
}

#define REASONABLE_LEN 200

static int
asctoeg(char *ss, short unsigned int *y, int oprec, LDPARMS *ldp)
{
unsigned short yy[NI], xt[NI], tt[NI];
int esign, decflg, sgnflg, nexp, exp, prec, lost;
int k, trail, c, rndsav;
long lexp;
unsigned short nsign, *p;
char *sp, *s, *lstr;
int lenldstr;
int mflag = 0;
char tmpstr[REASONABLE_LEN];

/* Copy the input string. */
c = strlen (ss) + 2;
if (c <= REASONABLE_LEN)
  lstr = tmpstr;
else
  {
    lstr = (char *) calloc (c, 1);
    mflag = 1;
  }
s = ss;
lenldstr = 0;
while( *s == ' ' ) /* skip leading spaces */
  {
    ++s;
    ++lenldstr;
  }
sp = lstr;
for( k=0; k<c; k++ )
	{
	if( (*sp++ = *s++) == '\0' )
		break;
	}
*sp = '\0';
s = lstr;

rndsav = ldp->rndprc;
ldp->rndprc = NBITS; /* Set to full precision */
lost = 0;
nsign = 0;
decflg = 0;
sgnflg = 0;
nexp = 0;
exp = 0;
prec = 0;
ecleaz( yy );
trail = 0;

nxtcom:
k = *s - '0';
if( (k >= 0) && (k <= 9) )
	{
/* Ignore leading zeros */
	if( (prec == 0) && (decflg == 0) && (k == 0) )
		goto donchr;
/* Identify and strip trailing zeros after the decimal point. */
	if( (trail == 0) && (decflg != 0) )
		{
		sp = s;
		while( (*sp >= '0') && (*sp <= '9') )
			++sp;
/* Check for syntax error */
		c = *sp & 0x7f;
		if( (c != 'e') && (c != 'E') && (c != '\0')
			&& (c != '\n') && (c != '\r') && (c != ' ')
			&& (c != ',') )
			goto error;
		--sp;
		while( *sp == '0' )
			*sp-- = 'z';
		trail = 1;
		if( *s == 'z' )
			goto donchr;
		}
/* If enough digits were given to more than fill up the yy register,
 * continuing until overflow into the high guard word yy[2]
 * guarantees that there will be a roundoff bit at the top
 * of the low guard word after normalization.
 */
	if( yy[2] == 0 )
		{
		if( decflg )
			nexp += 1; /* count digits after decimal point */
		eshup1( yy );	/* multiply current number by 10 */
		emovz( yy, xt );
		eshup1( xt );
		eshup1( xt );
		eaddm( xt, yy );
		ecleaz( xt );
		xt[NI-2] = (unsigned short )k;
		eaddm( xt, yy );
		}
	else
		{
		/* Mark any lost non-zero digit.  */
		lost |= k;
		/* Count lost digits before the decimal point.  */
		if (decflg == 0)
		        nexp -= 1;
		}
	prec += 1;
	goto donchr;
	}

switch( *s )
	{
	case 'z':
		break;
	case 'E':
	case 'e':
		goto expnt;
	case '.':	/* decimal point */
		if( decflg )
			goto error;
		++decflg;
		break;
	case '-':
		nsign = 0xffff;
		if( sgnflg )
			goto error;
		++sgnflg;
		break;
	case '+':
		if( sgnflg )
			goto error;
		++sgnflg;
		break;
	case ',':
	case ' ':
	case '\0':
	case '\n':
	case '\r':
		goto daldone;
	case 'i':
	case 'I':
		goto infinite;
	default:
	error:
#ifdef NANS
		enan( yy, NI*16 );
#else
		mtherr( "asctoe", DOMAIN );
		ecleaz(yy);
#endif
		goto aexit;
	}
donchr:
++s;
goto nxtcom;

/* Exponent interpretation */
expnt:

esign = 1;
exp = 0;
++s;
/* check for + or - */
if( *s == '-' )
	{
	esign = -1;
	++s;
	}
if( *s == '+' )
	++s;
while( (*s >= '0') && (*s <= '9') )
	{
	exp *= 10;
	exp += *s++ - '0';
	if (exp > 4977)
		{
		if (esign < 0)
			goto zero;
		else
			goto infinite;
		}
	}
if( esign < 0 )
	exp = -exp;
if( exp > 4932 )
	{
infinite:
	ecleaz(yy);
	yy[E] = 0x7fff;  /* infinity */
	goto aexit;
	}
if( exp < -4977 )
	{
zero:
	ecle