mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 03:27:39 +00:00
a089c07ddc
Cosmopolitan's printf-family functions will currently crash if one tries formatting a floating point number with a larger precision (large enough that gdtoa attempts to allocate memory to format the number) while under memory pressure (i.e. when malloc fails) because gdtoa fails to check if malloc fails. The added tests (which would previously crash under cosmopolitan without this patch) show how to reproduce the issue. This patch fixes this, and adds the aforementioned tests.
626 lines
17 KiB
C
626 lines
17 KiB
C
/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
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│ vi: set noet ft=c ts=8 sw=8 fenc=utf-8 :vi │
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╚──────────────────────────────────────────────────────────────────────────────╝
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│ │
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│ The author of this software is David M. Gay. │
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│ Please send bug reports to David M. Gay <dmg@acm.org> │
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│ or Justine Tunney <jtunney@gmail.com> │
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│ │
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│ Copyright (C) 1998, 1999 by Lucent Technologies │
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│ All Rights Reserved │
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│ │
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│ Permission to use, copy, modify, and distribute this software and │
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│ its documentation for any purpose and without fee is hereby │
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│ granted, provided that the above copyright notice appear in all │
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│ copies and that both that the copyright notice and this │
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│ permission notice and warranty disclaimer appear in supporting │
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│ documentation, and that the name of Lucent or any of its entities │
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│ not be used in advertising or publicity pertaining to │
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│ distribution of the software without specific, written prior │
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│ permission. │
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│ │
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│ LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, │
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│ INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. │
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│ IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY │
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│ SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES │
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│ WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER │
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│ IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, │
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│ ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF │
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│ THIS SOFTWARE. │
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│ │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/runtime/fenv.h"
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#include "third_party/gdtoa/gdtoa.internal.h"
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/* dtoa for IEEE arithmetic (dmg): convert double to ASCII string.
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*
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* Inspired by "How to Print Floating-Point Numbers Accurately" by
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* Guy L. Steele, Jr. and Jon L. White [Proc. ACM SIGPLAN '90, pp. 112-126].
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*
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* Modifications:
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* 1. Rather than iterating, we use a simple numeric overestimate
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* to determine k = floor(log10(d)). We scale relevant
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* quantities using O(log2(k)) rather than O(k) __gdtoa_multiplications.
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* 2. For some modes > 2 (corresponding to ecvt and fcvt), we don't
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* try to generate digits strictly left to right. Instead, we
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* compute with fewer bits and propagate the carry if necessary
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* when rounding the final digit up. This is often faster.
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* 3. Under the as__gdtoa_sumption that input will be rounded nearest,
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* mode 0 renders 1e23 as 1e23 rather than 9.999999999999999e22.
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* That is, we allow equality in stopping tests when the
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* round-nearest rule will give the same floating-point value
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* as would satisfaction of the stopping test with strict
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* inequality.
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* 4. We remove common factors of powers of 2 from relevant
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* quantities.
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* 5. When converting floating-point integers less than 1e16,
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* we use floating-point arithmetic rather than resorting
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* to __gdtoa_multiple-precision integers.
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* 6. When asked to produce fewer than 15 digits, we first try
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* to get by with floating-point arithmetic; we resort to
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* __gdtoa_multiple-precision integer arithmetic only if we cannot
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* guarantee that the floating-point calculation has given
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* the correctly rounded result. For k requested digits and
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* "uniformly" distributed input, the probability is
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* something like 10^(k-15) that we must resort to the Long
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* calculation.
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*/
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char *
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dtoa(double d0, int mode, int ndigits, int *decpt, int *sign, char **rve)
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{
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/* Arguments ndigits, decpt, sign are similar to those
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of ecvt and fcvt; trailing zeros are suppressed from
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the returned string. If not null, *rve is set to point
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to the end of the return value. If d is +-Infinity or NaN,
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then *decpt is set to 9999.
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mode:
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0 ==> shortest string that yields d when read in
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and rounded to nearest.
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1 ==> like 0, but with Steele & White stopping rule;
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e.g. with IEEE P754 arithmetic , mode 0 gives
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1e23 whereas mode 1 gives 9.999999999999999e22.
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2 ==> max(1,ndigits) significant digits. This gives a
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return value similar to that of ecvt, except
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that trailing zeros are suppressed.
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3 ==> through ndigits past the decimal point. This
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gives a return value similar to that from fcvt,
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except that trailing zeros are suppressed, and
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ndigits can be negative.
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4,5 ==> similar to 2 and 3, respectively, but (in
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round-nearest mode) with the tests of mode 0 to
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possibly return a shorter string that rounds to d.
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With IEEE arithmetic and compilation with
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-DHonor_FLT_ROUNDS, modes 4 and 5 behave the same
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as modes 2 and 3 when FLT_ROUNDS != 1.
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6-9 ==> Debugging modes similar to mode - 4: don't try
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fast floating-point estimate (if applicable).
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Values of mode other than 0-9 are treated as mode 0.
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Sufficient space is allocated to the return value
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to hold the suppressed trailing zeros.
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*/
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ThInfo *TI = 0;
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int bbits, b2, b5, be, dig, i, ieps, ilim, ilim0, ilim1,
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j, j1, k, k0, k_check, leftright, m2, m5, s2, s5,
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spec_case, try_quick;
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Long L;
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int denorm;
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ULong x;
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Bigint *b, *b1, *delta, *mlo, *mhi, *S;
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U d, d2, eps, eps1;
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double ds;
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char *s, *s0;
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int Rounding;
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Rounding = FLT_ROUNDS;
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d.d = d0;
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if (word0(&d) & Sign_bit) {
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/* set sign for everything, including 0's and NaNs */
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*sign = 1;
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word0(&d) &= ~Sign_bit; /* clear sign bit */
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}
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else
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*sign = 0;
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if ((word0(&d) & Exp_mask) == Exp_mask)
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{
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/* Infinity or NaN */
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*decpt = 9999;
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if (!word1(&d) && !(word0(&d) & 0xfffff))
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return __gdtoa_nrv_alloc("Infinity", rve, 8, &TI);
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return __gdtoa_nrv_alloc("NaN", rve, 3, &TI);
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}
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if (!dval(&d)) {
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*decpt = 1;
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return __gdtoa_nrv_alloc("0", rve, 1, &TI);
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}
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if (Rounding >= 2) {
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if (*sign)
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Rounding = Rounding == 2 ? 0 : 2;
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else
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if (Rounding != 2)
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Rounding = 0;
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}
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b = __gdtoa_d2b(dval(&d), &be, &bbits, &TI);
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if (( i = (int)(word0(&d) >> Exp_shift1 & (Exp_mask>>Exp_shift1)) )!=0) {
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dval(&d2) = dval(&d);
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word0(&d2) &= Frac_mask1;
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word0(&d2) |= Exp_11;
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/* log(x) ~=~ log(1.5) + (x-1.5)/1.5
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* log10(x) = log(x) / log(10)
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* ~=~ log(1.5)/log(10) + (x-1.5)/(1.5*log(10))
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* log10(&d) = (i-Bias)*log(2)/log(10) + log10(&d2)
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*
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* This suggests computing an approximation k to log10(&d) by
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*
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* k = (i - Bias)*0.301029995663981
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* + ( (d2-1.5)*0.289529654602168 + 0.176091259055681 );
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*
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* We want k to be too large rather than too small.
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* The error in the first-order Taylor series approximation
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* is in our favor, so we just round up the constant enough
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* to compensate for any error in the __gdtoa_multiplication of
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* (i - Bias) by 0.301029995663981; since |i - Bias| <= 1077,
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* and 1077 * 0.30103 * 2^-52 ~=~ 7.2e-14,
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* adding 1e-13 to the constant term more than suffices.
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* Hence we adjust the constant term to 0.1760912590558.
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* (We could get a more accurate k by invoking log10,
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* but this is probably not worthwhile.)
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*/
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i -= Bias;
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denorm = 0;
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}
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else {
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/* d is denormalized */
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i = bbits + be + (Bias + (P-1) - 1);
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x = i > 32 ? word0(&d) << (64 - i) | word1(&d) >> (i - 32)
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: word1(&d) << (32 - i);
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dval(&d2) = x;
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word0(&d2) -= 31*Exp_msk1; /* adjust exponent */
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i -= (Bias + (P-1) - 1) + 1;
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denorm = 1;
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}
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ds = (dval(&d2)-1.5)*0.289529654602168 + 0.1760912590558 + i*0.301029995663981;
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k = (int)ds;
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if (ds < 0. && ds != k)
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k--; /* want k = floor(ds) */
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k_check = 1;
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if (k >= 0 && k <= Ten_pmax) {
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if (dval(&d) < __gdtoa_tens[k])
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k--;
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k_check = 0;
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}
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j = bbits - i - 1;
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if (j >= 0) {
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b2 = 0;
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s2 = j;
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}
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else {
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b2 = -j;
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s2 = 0;
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}
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if (k >= 0) {
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b5 = 0;
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s5 = k;
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s2 += k;
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}
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else {
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b2 -= k;
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b5 = -k;
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s5 = 0;
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}
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if (mode < 0 || mode > 9)
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mode = 0;
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try_quick = Rounding == 1;
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if (mode > 5) {
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mode -= 4;
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try_quick = 0;
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}
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leftright = 1;
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ilim = ilim1 = -1; /* Values for cases 0 and 1; done here to */
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/* silence erroneous "gcc -Wall" warning. */
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switch(mode) {
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case 0:
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case 1:
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i = 18;
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ndigits = 0;
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break;
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case 2:
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leftright = 0;
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/* no break */
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case 4:
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if (ndigits <= 0)
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ndigits = 1;
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ilim = ilim1 = i = ndigits;
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break;
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case 3:
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leftright = 0;
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/* no break */
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case 5:
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i = ndigits + k + 1;
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ilim = i;
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ilim1 = i - 1;
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if (i <= 0)
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i = 1;
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}
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s = s0 = __gdtoa_rv_alloc(i, &TI);
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if (s0 == NULL)
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goto ret1;
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if (mode > 1 && Rounding != 1)
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leftright = 0;
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if (ilim >= 0 && ilim <= Quick_max && try_quick) {
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/* Try to get by with floating-point arithmetic. */
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i = 0;
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j1 = 0;
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dval(&d2) = dval(&d);
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k0 = k;
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ilim0 = ilim;
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ieps = 2; /* conservative */
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if (k > 0) {
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ds = __gdtoa_tens[k&0xf];
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j = k >> 4;
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if (j & Bletch) {
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/* prevent overflows */
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j &= Bletch - 1;
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dval(&d) /= __gdtoa_bigtens[n___gdtoa_bigtens-1];
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ieps++;
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}
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for(; j; j >>= 1, i++)
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if (j & 1) {
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ieps++;
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ds *= __gdtoa_bigtens[i];
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}
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dval(&d) /= ds;
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}
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else if (( j1 = -k )!=0) {
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dval(&d) *= __gdtoa_tens[j1 & 0xf];
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for(j = j1 >> 4; j; j >>= 1, i++)
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if (j & 1) {
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ieps++;
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dval(&d) *= __gdtoa_bigtens[i];
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}
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}
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if (k_check && dval(&d) < 1. && ilim > 0) {
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if (ilim1 <= 0)
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goto fast_failed;
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ilim = ilim1;
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k--;
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dval(&d) *= 10.;
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ieps++;
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}
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dval(&eps) = ieps*dval(&d) + 7.;
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word0(&eps) -= (P-1)*Exp_msk1;
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if (ilim == 0) {
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S = mhi = 0;
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dval(&d) -= 5.;
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if (dval(&d) > dval(&eps))
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goto one_digit;
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if (dval(&d) < -dval(&eps))
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goto no_digits;
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goto fast_failed;
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}
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if (leftright) {
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/* Use Steele & White method of only
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* generating digits needed.
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*/
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dval(&eps) = 0.5/__gdtoa_tens[ilim-1] - dval(&eps);
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if (k0 < 0 && j1 >= 307) {
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eps1.d = 1.01e256; /* 1.01 allows roundoff in the next few lines */
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word0(&eps1) -= Exp_msk1 * (Bias+P-1);
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dval(&eps1) *= __gdtoa_tens[j1 & 0xf];
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for(i = 0, j = (j1-256) >> 4; j; j >>= 1, i++)
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if (j & 1)
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dval(&eps1) *= __gdtoa_bigtens[i];
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if (eps.d < eps1.d)
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eps.d = eps1.d;
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if (10. - d.d < 10.*eps.d && eps.d < 1.) {
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/* eps.d < 1. excludes trouble with the tiniest denormal */
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*s++ = '1';
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++k;
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goto ret1;
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}
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}
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for(i = 0;;) {
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L = dval(&d);
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dval(&d) -= L;
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*s++ = '0' + (int)L;
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if (dval(&d) < dval(&eps))
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goto retc;
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if (1. - dval(&d) < dval(&eps))
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goto bump_up;
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if (++i >= ilim)
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break;
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dval(&eps) *= 10.;
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dval(&d) *= 10.;
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}
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}
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else {
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/* Generate ilim digits, then fix them up. */
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dval(&eps) *= __gdtoa_tens[ilim-1];
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for(i = 1;; i++, dval(&d) *= 10.) {
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L = (Long)(dval(&d));
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if (!(dval(&d) -= L))
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ilim = i;
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*s++ = '0' + (int)L;
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if (i == ilim) {
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if (dval(&d) > 0.5 + dval(&eps))
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goto bump_up;
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else if (dval(&d) < 0.5 - dval(&eps))
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goto retc;
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break;
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}
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}
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}
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fast_failed:
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s = s0;
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dval(&d) = dval(&d2);
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k = k0;
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ilim = ilim0;
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}
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/* Do we have a "small" integer? */
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if (be >= 0 && k <= Int_max) {
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/* Yes. */
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ds = __gdtoa_tens[k];
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if (ndigits < 0 && ilim <= 0) {
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S = mhi = 0;
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if (ilim < 0 || dval(&d) <= 5*ds)
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goto no_digits;
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goto one_digit;
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}
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for(i = 1;; i++, dval(&d) *= 10.) {
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L = (Long)(dval(&d) / ds);
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dval(&d) -= L*ds;
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/* If FLT_ROUNDS == 2, L will usually be high by 1 */
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if (dval(&d) < 0) {
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L--;
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dval(&d) += ds;
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}
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*s++ = '0' + (int)L;
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if (!dval(&d)) {
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break;
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}
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if (i == ilim) {
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if (mode > 1)
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switch(Rounding) {
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case 0: goto retc;
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case 2: goto bump_up;
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}
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dval(&d) += dval(&d);
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if (dval(&d) > ds || (dval(&d) == ds && L & 1)) {
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bump_up:
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while(*--s == '9')
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if (s == s0) {
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k++;
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*s = '0';
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break;
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}
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++*s++;
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}
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break;
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}
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}
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goto retc;
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}
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m2 = b2;
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m5 = b5;
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mhi = mlo = 0;
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if (leftright) {
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i = denorm ? be + (Bias + (P-1) - 1 + 1) : 1 + P - bbits;
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b2 += i;
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s2 += i;
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mhi = __gdtoa_i2b(1, &TI);
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}
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if (m2 > 0 && s2 > 0) {
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i = m2 < s2 ? m2 : s2;
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b2 -= i;
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m2 -= i;
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s2 -= i;
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}
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if (b5 > 0) {
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if (leftright) {
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if (m5 > 0) {
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mhi = __gdtoa_pow5mult(mhi, m5, &TI);
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b1 = __gdtoa_mult(mhi, b, &TI);
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__gdtoa_Bfree(b, &TI);
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b = b1;
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}
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if (( j = b5 - m5 )!=0)
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b = __gdtoa_pow5mult(b, j, &TI);
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}
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else
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b = __gdtoa_pow5mult(b, b5, &TI);
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}
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S = __gdtoa_i2b(1, &TI);
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if (s5 > 0)
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S = __gdtoa_pow5mult(S, s5, &TI);
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/* Check for special case that d is a normalized power of 2. */
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spec_case = 0;
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if ((mode < 2 || leftright) && Rounding == 1) {
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if (!word1(&d) && !(word0(&d) & Bndry_mask) &&
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word0(&d) & (Exp_mask & ~Exp_msk1)) {
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/* The special case */
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b2 += Log2P;
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s2 += Log2P;
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spec_case = 1;
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}
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}
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/* Arrange for convenient computation of quotients:
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* shift left if necessary so divisor has 4 leading 0 bits.
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*
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* Perhaps we should just compute leading 28 bits of S once
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* and for all and pass them and a shift to __gdtoa_quorem, so it
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* can do shifts and ors to compute the numerator for q.
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*/
|
|
if (( i = ((s5 ? 32 - hi0bits(S->x[S->wds-1]) : 1) + s2) & 0x1f )!=0)
|
|
i = 32 - i;
|
|
if (i > 4) {
|
|
i -= 4;
|
|
b2 += i;
|
|
m2 += i;
|
|
s2 += i;
|
|
}
|
|
else if (i < 4) {
|
|
i += 28;
|
|
b2 += i;
|
|
m2 += i;
|
|
s2 += i;
|
|
}
|
|
if (b2 > 0)
|
|
b = __gdtoa_lshift(b, b2, &TI);
|
|
if (s2 > 0)
|
|
S = __gdtoa_lshift(S, s2, &TI);
|
|
if (k_check) {
|
|
if (__gdtoa_cmp(b,S) < 0) {
|
|
k--;
|
|
b = __gdtoa_multadd(b, 10, 0, &TI); /* we botched the k estimate */
|
|
if (leftright)
|
|
mhi = __gdtoa_multadd(mhi, 10, 0, &TI);
|
|
ilim = ilim1;
|
|
}
|
|
}
|
|
if (ilim <= 0 && (mode == 3 || mode == 5)) {
|
|
if (ilim < 0 || __gdtoa_cmp(b,S = __gdtoa_multadd(S,5,0,&TI)) <= 0) {
|
|
/* no digits, fcvt style */
|
|
no_digits:
|
|
k = -1 - ndigits;
|
|
goto ret;
|
|
}
|
|
one_digit:
|
|
*s++ = '1';
|
|
k++;
|
|
goto ret;
|
|
}
|
|
if (leftright) {
|
|
if (m2 > 0)
|
|
mhi = __gdtoa_lshift(mhi, m2, &TI);
|
|
/* Compute mlo -- check for special case
|
|
* that d is a normalized power of 2.
|
|
*/
|
|
mlo = mhi;
|
|
if (spec_case) {
|
|
mhi = __gdtoa_Balloc(mhi->k, &TI);
|
|
Bcopy(mhi, mlo);
|
|
mhi = __gdtoa_lshift(mhi, Log2P, &TI);
|
|
}
|
|
for(i = 1;;i++) {
|
|
dig = __gdtoa_quorem(b,S) + '0';
|
|
/* Do we yet have the shortest decimal string
|
|
* that will round to d?
|
|
*/
|
|
j = __gdtoa_cmp(b, mlo);
|
|
delta = __gdtoa_diff(S, mhi, &TI);
|
|
j1 = delta->sign ? 1 : __gdtoa_cmp(b, delta);
|
|
__gdtoa_Bfree(delta, &TI);
|
|
if (j1 == 0 && mode != 1 && !(word1(&d) & 1) && Rounding >= 1) {
|
|
if (dig == '9')
|
|
goto round_9_up;
|
|
if (j > 0)
|
|
dig++;
|
|
*s++ = dig;
|
|
goto ret;
|
|
}
|
|
if (j < 0 || (j == 0 && mode != 1 && !(word1(&d) & 1)
|
|
)) {
|
|
if (!b->x[0] && b->wds <= 1) {
|
|
goto accept_dig;
|
|
}
|
|
if (mode > 1)
|
|
switch(Rounding) {
|
|
case 0: goto accept_dig;
|
|
case 2: goto keep_dig;
|
|
}
|
|
if (j1 > 0) {
|
|
b = __gdtoa_lshift(b, 1, &TI);
|
|
j1 = __gdtoa_cmp(b, S);
|
|
if ((j1 > 0 || (j1 == 0 && dig & 1))
|
|
&& dig++ == '9')
|
|
goto round_9_up;
|
|
}
|
|
accept_dig:
|
|
*s++ = dig;
|
|
goto ret;
|
|
}
|
|
if (j1 > 0) {
|
|
if (!Rounding && mode > 1)
|
|
goto accept_dig;
|
|
if (dig == '9') { /* possible if i == 1 */
|
|
round_9_up:
|
|
*s++ = '9';
|
|
goto roundoff;
|
|
}
|
|
*s++ = dig + 1;
|
|
goto ret;
|
|
}
|
|
keep_dig:
|
|
*s++ = dig;
|
|
if (i == ilim)
|
|
break;
|
|
b = __gdtoa_multadd(b, 10, 0, &TI);
|
|
if (mlo == mhi)
|
|
mlo = mhi = __gdtoa_multadd(mhi, 10, 0, &TI);
|
|
else {
|
|
mlo = __gdtoa_multadd(mlo, 10, 0, &TI);
|
|
mhi = __gdtoa_multadd(mhi, 10, 0, &TI);
|
|
}
|
|
}
|
|
}
|
|
else {
|
|
for(i = 1;; i++) {
|
|
*s++ = dig = __gdtoa_quorem(b,S) + '0';
|
|
if (!b->x[0] && b->wds <= 1) {
|
|
goto ret;
|
|
}
|
|
if (i >= ilim)
|
|
break;
|
|
b = __gdtoa_multadd(b, 10, 0, &TI);
|
|
}
|
|
}
|
|
|
|
/* Round off last digit */
|
|
switch(Rounding) {
|
|
case 0: goto trimzeros;
|
|
case 2: goto roundoff;
|
|
}
|
|
b = __gdtoa_lshift(b, 1, &TI);
|
|
j = __gdtoa_cmp(b, S);
|
|
if (j > 0 || (j == 0 && dig & 1))
|
|
{
|
|
roundoff:
|
|
while(*--s == '9')
|
|
if (s == s0) {
|
|
k++;
|
|
*s++ = '1';
|
|
goto ret;
|
|
}
|
|
++*s++;
|
|
}
|
|
else {
|
|
trimzeros:
|
|
while(*--s == '0');
|
|
s++;
|
|
}
|
|
ret:
|
|
__gdtoa_Bfree(S, &TI);
|
|
if (mhi) {
|
|
if (mlo && mlo != mhi)
|
|
__gdtoa_Bfree(mlo, &TI);
|
|
__gdtoa_Bfree(mhi, &TI);
|
|
}
|
|
retc:
|
|
while(s > s0 && s[-1] == '0')
|
|
--s;
|
|
ret1:
|
|
__gdtoa_Bfree(b, &TI);
|
|
if (s != NULL)
|
|
*s = 0;
|
|
*decpt = k + 1;
|
|
if (rve)
|
|
*rve = s;
|
|
return s0;
|
|
}
|