101 lines
2.1 KiB
C
101 lines
2.1 KiB
C
#include <_ansi.h>
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#include <limits.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <reent.h>
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#include "vfieeefp.h"
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/*
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* Convert a string to a fixed-point (sign + 31-bits) value.
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*
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* Ignores `locale' stuff.
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*/
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__int32_t
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_DEFUN (_strtosfix32_r, (rptr, nptr, endptr),
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struct _reent *rptr _AND
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_CONST char *nptr _AND
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char **endptr)
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{
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union double_union dbl;
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int exp, negexp, sign;
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unsigned long tmp, tmp2;
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long result = 0;
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dbl.d = _strtod_r (rptr, nptr, endptr);
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/* treat NAN as domain error, +/- infinity as saturation */
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if (!finite(dbl.d))
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{
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if (isnan (dbl.d))
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{
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rptr->_errno = EDOM;
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return 0;
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}
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rptr->_errno = ERANGE;
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if (word0(dbl) & Sign_bit)
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return LONG_MIN;
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return LONG_MAX;
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}
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/* check for normal saturation */
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if (dbl.d >= 1.0)
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{
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rptr->_errno = ERANGE;
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return LONG_MAX;
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}
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else if (dbl.d < -1.0)
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{
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rptr->_errno = ERANGE;
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return LONG_MIN;
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}
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/* otherwise we have normal number in range */
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/* strip off sign and exponent */
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sign = word0(dbl) & Sign_bit;
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exp = ((word0(dbl) & Exp_mask) >> Exp_shift) - Bias;
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negexp = -exp;
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if (negexp > 31)
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return 0;
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word0(dbl) &= ~(Exp_mask | Sign_bit);
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/* add in implicit normalized bit */
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word0(dbl) |= Exp_msk1;
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/* shift so result is contained in single word */
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tmp = word0(dbl) << Ebits;
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tmp |= ((unsigned long)word1(dbl) >> (32 - Ebits));
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if (negexp != 0)
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{
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/* perform rounding */
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tmp2 = tmp + (1 << (negexp - 1));
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result = (long)(tmp2 >> negexp);
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/* check if rounding caused carry bit which must be added into result */
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if (tmp2 < tmp)
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result |= (1 << (32 - negexp));
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/* check if positive saturation has occurred because of rounding */
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if (!sign && result < 0)
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{
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rptr->_errno = ERANGE;
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return LONG_MAX;
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}
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}
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else
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{
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/* we have -1.0, no rounding necessary */
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return LONG_MIN;
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}
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return sign ? -result : result;
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}
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#ifndef _REENT_ONLY
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__int32_t
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_DEFUN (strtosfix32, (s, ptr, base),
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_CONST char *s _AND
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char **ptr)
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{
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return _strtosfix32_r (_REENT, s, ptr);
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}
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#endif
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