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30891f35fa
We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
150 lines
4.5 KiB
C
150 lines
4.5 KiB
C
/* e_fmodl.c -- long double version of e_fmod.c.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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* __ieee754_fmodl(x,y)
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* Return x mod y in exact arithmetic
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* Method: shift and subtract
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*/
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#include <math.h>
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#include <math_private.h>
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#include <ieee754.h>
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#include <libm-alias-finite.h>
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static const long double one = 1.0, Zero[] = {0.0, -0.0,};
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long double
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__ieee754_fmodl (long double x, long double y)
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{
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int64_t hx, hy, hz, sx, sy;
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uint64_t lx, ly, lz;
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int n, ix, iy;
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double xhi, xlo, yhi, ylo;
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ldbl_unpack (x, &xhi, &xlo);
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EXTRACT_WORDS64 (hx, xhi);
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EXTRACT_WORDS64 (lx, xlo);
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ldbl_unpack (y, &yhi, &ylo);
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EXTRACT_WORDS64 (hy, yhi);
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EXTRACT_WORDS64 (ly, ylo);
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sx = hx&0x8000000000000000ULL; /* sign of x */
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hx ^= sx; /* |x| */
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sy = hy&0x8000000000000000ULL; /* sign of y */
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hy ^= sy; /* |y| */
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/* purge off exception values */
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if(__builtin_expect(hy==0 ||
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(hx>=0x7ff0000000000000LL)|| /* y=0,or x not finite */
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(hy>0x7ff0000000000000LL),0)) /* or y is NaN */
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return (x*y)/(x*y);
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if (__glibc_unlikely (hx <= hy))
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{
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/* If |x| < |y| return x. */
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if (hx < hy)
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return x;
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/* At this point the absolute value of the high doubles of
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x and y must be equal. */
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if ((lx & 0x7fffffffffffffffLL) == 0
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&& (ly & 0x7fffffffffffffffLL) == 0)
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/* Both low parts are zero. The result should be an
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appropriately signed zero, but the subsequent logic
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could treat them as unequal, depending on the signs
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of the low parts. */
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return Zero[(uint64_t) sx >> 63];
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/* If the low double of y is the same sign as the high
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double of y (ie. the low double increases |y|)... */
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if (((ly ^ sy) & 0x8000000000000000LL) == 0
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/* ... then a different sign low double to high double
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for x or same sign but lower magnitude... */
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&& (int64_t) (lx ^ sx) < (int64_t) (ly ^ sy))
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/* ... means |x| < |y|. */
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return x;
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/* If the low double of x differs in sign to the high
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double of x (ie. the low double decreases |x|)... */
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if (((lx ^ sx) & 0x8000000000000000LL) != 0
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/* ... then a different sign low double to high double
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for y with lower magnitude (we've already caught
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the same sign for y case above)... */
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&& (int64_t) (lx ^ sx) > (int64_t) (ly ^ sy))
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/* ... means |x| < |y|. */
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return x;
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/* If |x| == |y| return x*0. */
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if ((lx ^ sx) == (ly ^ sy))
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return Zero[(uint64_t) sx >> 63];
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}
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/* Make the IBM extended format 105 bit mantissa look like the ieee854 112
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bit mantissa so the following operations will give the correct
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result. */
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ldbl_extract_mantissa(&hx, &lx, &ix, x);
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ldbl_extract_mantissa(&hy, &ly, &iy, y);
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if (__glibc_unlikely (ix == -IEEE754_DOUBLE_BIAS))
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{
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/* subnormal x, shift x to normal. */
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while ((hx & (1LL << 48)) == 0)
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{
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hx = (hx << 1) | (lx >> 63);
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lx = lx << 1;
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ix -= 1;
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}
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}
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if (__glibc_unlikely (iy == -IEEE754_DOUBLE_BIAS))
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{
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/* subnormal y, shift y to normal. */
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while ((hy & (1LL << 48)) == 0)
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{
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hy = (hy << 1) | (ly >> 63);
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ly = ly << 1;
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iy -= 1;
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}
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}
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/* fix point fmod */
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n = ix - iy;
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while(n--) {
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hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
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if(hz<0){hx = hx+hx+(lx>>63); lx = lx+lx;}
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else {
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if((hz|lz)==0) /* return sign(x)*0 */
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return Zero[(uint64_t)sx>>63];
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hx = hz+hz+(lz>>63); lx = lz+lz;
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}
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}
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hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
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if(hz>=0) {hx=hz;lx=lz;}
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/* convert back to floating value and restore the sign */
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if((hx|lx)==0) /* return sign(x)*0 */
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return Zero[(uint64_t)sx>>63];
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while(hx<0x0001000000000000LL) { /* normalize x */
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hx = hx+hx+(lx>>63); lx = lx+lx;
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iy -= 1;
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}
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if(__builtin_expect(iy>= -1022,0)) { /* normalize output */
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x = ldbl_insert_mantissa((sx>>63), iy, hx, lx);
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} else { /* subnormal output */
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n = -1022 - iy;
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/* We know 1 <= N <= 52, and that there are no nonzero
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bits in places below 2^-1074. */
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lx = (lx >> n) | ((uint64_t) hx << (64 - n));
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hx >>= n;
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x = ldbl_insert_mantissa((sx>>63), -1023, hx, lx);
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x *= one; /* create necessary signal */
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}
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return x; /* exact output */
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}
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libm_alias_finite (__ieee754_fmodl, __fmodl)
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