ldtoa.c

Newlib 嵌入式 C库 标准实现代码

	{ /* if zero exponent, then normalize the significand */
	if( (k = enormlz(yy)) > NBITS )
		ecleazs(yy);
	else
		yy[E] -= (unsigned short )(k-1);
	}
emovo( yy, y, ldp );
#endif /* !DEC */
}

/*
; e type to IEEE double precision
;	double d;
;	unsigned short x[NE];
;	etoe53( x, &d );
*/

#ifdef DEC

static void etoe53( x, e )
unsigned short *x, *e;
{
etodec( x, e ); /* see etodec.c */
}

static void toe53( x, y )
unsigned short *x, *y;
{
todec( x, y );
}

#else

static void toe53(short unsigned int *x, short unsigned int *y)
{
unsigned short i;
unsigned short *p;


#ifdef NANS
if( eiisnan(x) )
	{
	enan( y, 53 );
	return;
	}
#endif
p = &x[0];
#ifdef IBMPC
y += 3;
#endif
#ifdef DEC
y += 3;
#endif
*y = 0;	/* output high order */
if( *p++ )
	*y = 0x8000;	/* output sign bit */

i = *p++;
if( i >= (unsigned int )2047 )
	{	/* Saturate at largest number less than infinity. */
#ifdef USE_INFINITY
	*y |= 0x7ff0;
#ifdef IBMPC
	*(--y) = 0;
	*(--y) = 0;
	*(--y) = 0;
#else /* !IBMPC */
	++y;
	*y++ = 0;
	*y++ = 0;
	*y++ = 0;
#endif /* IBMPC */
#else /* !USE_INFINITY */
	*y |= (unsigned short )0x7fef;
#ifdef IBMPC
	*(--y) = 0xffff;
	*(--y) = 0xffff;
	*(--y) = 0xffff;
#else /* !IBMPC */
	++y;
	*y++ = 0xffff;
	*y++ = 0xffff;
	*y++ = 0xffff;
#endif
#endif /* !USE_INFINITY */
	return;
	}
if( i == 0 )
	{
	(void )eshift( x, 4 );
	}
else
	{
	i <<= 4;
	(void )eshift( x, 5 );
	}
i |= *p++ & (unsigned short )0x0f;	/* *p = xi[M] */
*y |= (unsigned short )i; /* high order output already has sign bit set */
#ifdef IBMPC
*(--y) = *p++;
*(--y) = *p++;
*(--y) = *p;
#else /* !IBMPC */
++y;
*y++ = *p++;
*y++ = *p++;
*y++ = *p++;
#endif /* !IBMPC */
}

#endif /* not DEC */
#endif /* LDBL_MANT_DIG == 53 */

#if LDBL_MANT_DIG == 24
/*
; Convert IEEE single precision to e type
;	float d;
;	unsigned short x[N+2];
;	dtox( &d, x );
*/
void e24toe( short unsigned int *pe, short unsigned int *y, LDPARMS *ldp )
{
register unsigned short r;
register unsigned short *p, *e;
unsigned short yy[NI];
int denorm, k;

e = pe;
denorm = 0;	/* flag if denormalized number */
ecleaz(yy);
#ifdef IBMPC
e += 1;
#endif
#ifdef DEC
e += 1;
#endif
r = *e;
yy[0] = 0;
if( r & 0x8000 )
	yy[0] = 0xffff;
yy[M] = (r & 0x7f) | 0200;
r &= ~0x807f;	/* strip sign and 7 significand bits */
#ifdef USE_INFINITY
if( r == 0x7f80 )
	{
#ifdef NANS
#ifdef MIEEE
	if( ((pe[0] & 0x7f) != 0) || (pe[1] != 0) )
		{
		enan( y, NBITS );
		return;
		}
#else  /* !MIEEE */
	if( ((pe[1] & 0x7f) != 0) || (pe[0] != 0) )
		{
		enan( y, NBITS );
		return;
		}
#endif /* !MIEEE */
#endif  /* NANS */
	eclear( y );
	einfin( y, ldp );
	if( yy[0] )
		eneg(y);
	return;
	}
#endif
r >>= 7;
/* If zero exponent, then the significand is denormalized.
 * So, take back the understood high significand bit. */ 
if( r == 0 )
	{
	denorm = 1;
	yy[M] &= ~0200;
	}
r += EXONE - 0177;
yy[E] = r;
p = &yy[M+1];
#ifdef IBMPC
*p++ = *(--e);
#endif
#ifdef DEC
*p++ = *(--e);
#endif
#ifdef MIEEE
++e;
*p++ = *e++;
#endif
(void )eshift( yy, -8 );
if( denorm )
	{ /* if zero exponent, then normalize the significand */
	if( (k = enormlz(yy)) > NBITS )
		ecleazs(yy);
	else
		yy[E] -= (unsigned short )(k-1);
	}
emovo( yy, y, ldp );
}

static void toe24(short unsigned int *x, short unsigned int *y)
{
unsigned short i;
unsigned short *p;

#ifdef NANS
if( eiisnan(x) )
	{
	enan( y, 24 );
	return;
	}
#endif
p = &x[0];
#ifdef IBMPC
y += 1;
#endif
#ifdef DEC
y += 1;
#endif
*y = 0;	/* output high order */
if( *p++ )
	*y = 0x8000;	/* output sign bit */

i = *p++;
if( i >= 255 )
	{	/* Saturate at largest number less than infinity. */
#ifdef USE_INFINITY
	*y |= (unsigned short )0x7f80;
#ifdef IBMPC
	*(--y) = 0;
#endif
#ifdef DEC
	*(--y) = 0;
#endif
#ifdef MIEEE
	++y;
	*y = 0;
#endif
#else /* !USE_INFINITY */
	*y |= (unsigned short )0x7f7f;
#ifdef IBMPC
	*(--y) = 0xffff;
#endif
#ifdef DEC
	*(--y) = 0xffff;
#endif
#ifdef MIEEE
	++y;
	*y = 0xffff;
#endif
#endif /* !USE_INFINITY */
	return;
	}
if( i == 0 )
	{
	(void )eshift( x, 7 );
	}
else
	{
	i <<= 7;
	(void )eshift( x, 8 );
	}
i |= *p++ & (unsigned short )0x7f;	/* *p = xi[M] */
*y |= i;	/* high order output already has sign bit set */
#ifdef IBMPC
*(--y) = *p;
#endif
#ifdef DEC
*(--y) = *p;
#endif
#ifdef MIEEE
++y;
*y = *p;
#endif
}
#endif /* LDBL_MANT_DIG == 24 */

/* Compare two e type numbers.
 *
 * unsigned short a[NE], b[NE];
 * ecmp( a, b );
 *
 *  returns +1 if a > b
 *           0 if a == b
 *          -1 if a < b
 *          -2 if either a or b is a NaN.
 */
static int ecmp(short unsigned int *a, short unsigned int *b)
{
unsigned short ai[NI], bi[NI];
register unsigned short *p, *q;
register int i;
int msign;

#ifdef NANS
if (eisnan (a)  || eisnan (b))
	return( -2 );
#endif
emovi( a, ai );
p = ai;
emovi( b, bi );
q = bi;

if( *p != *q )
	{ /* the signs are different */
/* -0 equals + 0 */
	for( i=1; i<NI-1; i++ )
		{
		if( ai[i] != 0 )
			goto nzro;
		if( bi[i] != 0 )
			goto nzro;
		}
	return(0);
nzro:
	if( *p == 0 )
		return( 1 );
	else
		return( -1 );
	}
/* both are the same sign */
if( *p == 0 )
	msign = 1;
else
	msign = -1;
i = NI-1;
do
	{
	if( *p++ != *q++ )
		{
		goto diff;
		}
	}
while( --i > 0 );

return(0);	/* equality */



diff:

if( *(--p) > *(--q) )
	return( msign );		/* p is bigger */
else
	return( -msign );	/* p is littler */
}


/*
;	Shift significand
;
;	Shifts significand area up or down by the number of bits
;	given by the variable sc.
*/
static int eshift(short unsigned int *x, int sc)
{
unsigned short lost;
unsigned short *p;

if( sc == 0 )
	return( 0 );

lost = 0;
p = x + NI-1;

if( sc < 0 )
	{
	sc = -sc;
	while( sc >= 16 )
		{
		lost |= *p;	/* remember lost bits */
		eshdn6(x);
		sc -= 16;
		}

	while( sc >= 8 )
		{
		lost |= *p & 0xff;
		eshdn8(x);
		sc -= 8;
		}

	while( sc > 0 )
		{
		lost |= *p & 1;
		eshdn1(x);
		sc -= 1;
		}
	}
else
	{
	while( sc >= 16 )
		{
		eshup6(x);
		sc -= 16;
		}

	while( sc >= 8 )
		{
		eshup8(x);
		sc -= 8;
		}

	while( sc > 0 )
		{
		eshup1(x);
		sc -= 1;
		}
	}
if( lost )
	lost = 1;
return( (int )lost );
}



/*
;	normalize
;
; Shift normalizes the significand area pointed to by argument
; shift count (up = positive) is returned.
*/
static int enormlz(short unsigned int *x)
{
register unsigned short *p;
int sc;

sc = 0;
p = &x[M];
if( *p != 0 )
	goto normdn;
++p;
if( *p & 0x8000 )
	return( 0 );	/* already normalized */
while( *p == 0 )
	{
	eshup6(x);
	sc += 16;
/* With guard word, there are NBITS+16 bits available.
 * return true if all are zero.
 */
	if( sc > NBITS )
		return( sc );
	}
/* see if high byte is zero */
while( (*p & 0xff00) == 0 )
	{
	eshup8(x);
	sc += 8;
	}
/* now shift 1 bit at a time */
while( (*p  & 0x8000) == 0)
	{
	eshup1(x);
	sc += 1;
	if( sc > (NBITS+16) )
		{
		mtherr( "enormlz", UNDERFLOW );
		return( sc );
		}
	}
return( sc );

/* Normalize by shifting down out of the high guard word
   of the significand */
normdn:

if( *p & 0xff00 )
	{
	eshdn8(x);
	sc -= 8;
	}
while( *p != 0 )
	{
	eshdn1(x);
	sc -= 1;

	if( sc < -NBITS )
		{
		mtherr( "enormlz", OVERFLOW );
		return( sc );
		}
	}
return( sc );
}




/* Convert e type number to decimal format ASCII string.
 * The constants are for 64 bit precision.
 */

#define NTEN 12
#define MAXP 4096

#if NE == 10
static unsigned short etens[NTEN + 1][NE] =
{
  {0x6576, 0x4a92, 0x804a, 0x153f,
   0xc94c, 0x979a, 0x8a20, 0x5202, 0xc460, 0x7525,},	/* 10**4096 */
  {0x6a32, 0xce52, 0x329a, 0x28ce,
   0xa74d, 0x5de4, 0xc53d, 0x3b5d, 0x9e8b, 0x5a92,},	/* 10**2048 */
  {0x526c, 0x50ce, 0xf18b, 0x3d28,
   0x650d, 0x0c17, 0x8175, 0x7586, 0xc976, 0x4d48,},
  {0x9c66, 0x58f8, 0xbc50, 0x5c54,
   0xcc65, 0x91c6, 0xa60e, 0xa0ae, 0xe319, 0x46a3,},
  {0x851e, 0xeab7, 0x98fe, 0x901b,
   0xddbb, 0xde8d, 0x9df9, 0xebfb, 0xaa7e, 0x4351,},
  {0x0235, 0x0137, 0x36b1, 0x336c,
   0xc66f, 0x8cdf, 0x80e9, 0x47c9, 0x93ba, 0x41a8,},
  {0x50f8, 0x25fb, 0xc76b, 0x6b71,
   0x3cbf, 0xa6d5, 0xffcf, 0x1f49, 0xc278, 0x40d3,},
  {0x0000, 0x0000, 0x0000, 0x0000,
   0xf020, 0xb59d, 0x2b70, 0xada8, 0x9dc5, 0x4069,},
  {0x0000, 0x0000, 0x0000, 0x0000,
   0x0000, 0x0000, 0x0400, 0xc9bf, 0x8e1b, 0x4034,},
  {0x0000, 0x0000, 0x0000, 0x0000,
   0x0000, 0x0000, 0x0000, 0x2000, 0xbebc, 0x4019,},
  {0x0000, 0x0000, 0x0000, 0x0000,
   0x0000, 0x0000, 0x0000, 0x0000, 0x9c40, 0x400c,},
  {0x0000, 0x0000, 0x0000, 0x0000,
   0x0000, 0x0000, 0x0000, 0x0000, 0xc800, 0x4005,},
  {0x0000, 0x0000, 0x0000, 0x0000,
   0x0000, 0x0000, 0x0000, 0x0000, 0xa000, 0x4002,},	/* 10**1 */
};

static unsigned short emtens[NTEN + 1][NE] =
{
  {0x2030, 0xcffc, 0xa1c3, 0x8123,
   0x2de3, 0x9fde, 0xd2ce, 0x04c8, 0xa6dd, 0x0ad8,},	/* 10**-4096 */
  {0x8264, 0xd2cb, 0xf2ea, 0x12d4,
   0x4925, 0x2de4, 0x3436, 0x534f, 0xceae, 0x256b,},	/* 10**-2048 */
  {0xf53f, 0xf698, 0x6bd3, 0x0158,
   0x87a6, 0xc0bd, 0xda57, 0x82a5, 0xa2a6, 0x32b5,},
  {0xe731, 0x04d4, 0xe3f2, 0xd332,
   0x7132, 0xd21c, 0xdb23, 0xee32, 0x9049, 0x395a,},
  {0xa23e, 0x5308, 0xfefb, 0x1155,
   0xfa91, 0x1939, 0x637a, 0x4325, 0xc031, 0x3cac,},
  {0xe26d, 0xdbde, 0xd05d, 0xb3f6,
   0xac7c, 0xe4a0, 0x64bc, 0x467c, 0xddd0, 0x3e55,},
  {0x2a20, 0x6224, 0x47b3, 0x98d7,
   0x3f23, 0xe9a5, 0xa539, 0xea27, 0xa87f, 0x3f2a,},
  {0x0b5b, 0x4af2, 0xa581, 0x18ed,
   0x67de, 0x94ba, 0x4539, 0x1ead, 0xcfb1, 0x3f94,},
  {0xbf71, 0xa9b3, 0x7989, 0xbe68,
   0x4c2e, 0xe15b, 0xc44d, 0x94be, 0xe695, 0x3fc9,},
  {0x3d4d, 0x7c3d, 0x36ba, 0x0d2b,
   0xfdc2, 0xcefc, 0x8461, 0x7711, 0xabcc, 0x3fe4,},
  {0xc155, 0xa4a8, 0x404e, 0x6113,
   0xd3c3, 0x652b, 0xe219, 0x1758, 0xd1b7, 0x3ff1,},
  {0xd70a, 0x70a3, 0x0a3d, 0xa3d7,
   0x3d70, 0xd70a, 0x70a3, 0x0a3d, 0xa3d7, 0x3ff8,},
  {0xcccd, 0xcccc, 0xcccc, 0xcccc,
   0xcccc, 0xcccc, 0xcccc, 0xcccc, 0xcccc, 0x3ffb,},	/* 10**-1 */
};
#else
static unsigned short etens[NTEN+1][NE] = {
{0xc94c,0x979a,0x8a20,0x5202,0xc460,0x7525,},/* 10**4096 */
{0xa74d,0x5de4,0xc53d,0x3b5d,0x9e8b,0x5a92,},/* 10**2048 */
{0x650d,0x0c17,0x8175,0x7586,0xc976,0x4d48,},
{0xcc65,0x91c6,0xa60e,0xa0ae,0xe319,0x46a3,},
{0xddbc,0xde8d,0x9df9,0xebfb,0xaa7e,0x4351,},
{0xc66f,0x8cdf,0x80e9,0x47c9,0x93ba,0x41a8,},
{0x3cbf,0xa6d5,0xffcf,0x1f49,0xc278,0x40d3,},
{0xf020,0xb59d,0x2b70,0xada8,0x9dc5,0x4069,},
{0x0000,0x0000,0x0400,0xc9bf,0x8e1b,0x4034,},
{0x0000,0x0000,0x0000,0x2000,0xbebc,0x4019,},
{0x0000,0x0000,0x0000,0x0000,0x9c40,0x400c,},
{0x0000,0x0000,0x0000,0x0000,0xc800,0x4005,},
{0x0000,0x0000,0x0000,0x0000,0xa000,0x4002,}, /* 10**1 */
};

static unsigned short emtens[NTEN+1][NE] = {
{0x2de4,0x9fde,0xd2ce,0x04c8,0xa6dd,0x0ad8,}, /* 10**-4096 */
{0x4925,0x2de4,0x3436,0x534f,0xceae,0x256b,}, /* 10**-2048 */
{0x87a6,0xc0bd,0xda57,0x82a5,0xa2a6,0x32b5,},
{0x7133,0xd21c,0xdb23,0xee32,0x9049,0x395a,},
{0xfa91,0x1939,0x637a,0x4325,0xc031,0x3cac,},
{0xac7d,0xe4a0,0x64bc,0x467c,0xddd0,0x3e55,},
{0x3f24,0xe9a5,0xa539,0xea27,0xa87f,0x3f2a,},
{0x67de,0x94ba,0x4539,0x1ead,0xcfb1,0x3f94,},
{0x4c2f,0xe15b,0xc44d,0x94be,0xe695,0x3fc9,},
{0xfdc2,0xcefc,0x8461,0x7711,0xabcc,0x3fe4,},
{0xd3c3,0x652b,0xe219,0x1758,0xd1b7,0x3ff1,},
{0x3d71,0xd70a,0x70a3,0x0a3d,0xa3d7,0x3ff8,},
{0xcccd,0xcccc,0xcccc,0xcccc,0xcccc,0x3ffb,}, /* 10**-1 */
};
#endif



/* ASCII string outputs for unix */


#if 0
void _IO_ldtostr(x, string, ndigs, flags, fmt)
long double *x;
char *string;
int ndigs;
int flags;
char fmt;
{
unsigned short w[NI];
char *t, *u;
LDPARMS rnd;
LDPARMS *ldp = &rnd;

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

if (sizeof(long double) == 16)
  e113toe( (unsigned short *)x, w, ldp );
else
  e64toe( (unsigned short *)x, w, ldp );

etoasc( w, string, ndigs, -1, ldp );
if( ndigs == 0 && flags == 0 )
	{
	/* Delete the decimal point unless alternate format.  */
	t = string;	
	while( *t != '.' )
		++t;
	u = t +  1;
	while( *t != '\0' )
		*t++ = *u++;
	}
if (*string == ' ')
	{
	t = string;	
	u = t + 1;
	while( *t != '\0' )
		*t++ = *u++;
	}
if (fmt == 'E')
	{
	t = string;	
	while( *t != 'e' )
		++t;
	*t = 'E';
	}
}

#endif

/* This routine will not return more than NDEC+1 digits. */

char *
_ldtoa_r (struct _reent *ptr, long double d, int mode, int ndigits, int *decpt, 
          int *sign, char **rve)
{
unsigned short e[NI];
char *s, *p;
int i, j, k;
int orig_ndigits;
LDPARMS rnd;
LDPARMS *ldp = &rnd;
char *outstr;
char outbuf[NDEC + MAX_EXP_DIGITS + 10];
union uconv du;
du.d = d;

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

  _REENT_CHECK_MP(ptr);

/* reentrancy addition to use mprec storage pool */
if (_REENT_MP_RESULT(ptr))
  {
    _REENT_MP_RESULT(ptr)->_k = _REENT_MP_RESULT_K(ptr);
    _REENT_MP_RESULT(ptr)->_maxwds = 1 << _REENT_MP_RESULT_K(ptr);
    Bfree (ptr, _REENT_MP_RESULT(ptr));
    _REENT_MP_RESULT(ptr) = 0;
  }

#if LDBL_MANT_DIG == 24
e24toe( &du.pe, e, ldp );
#elif LDBL_MANT_DIG == 53
e53toe( &du.pe, e, ldp );
#elif LDBL_MANT_DIG == 64
e64toe( &du.pe, e, ldp );
#else
e113toe( &du.pe, e, ldp );
#endif

if( eisneg(e) )