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@@ -1,68 +1,37 @@
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-/* origin: FreeBSD /usr/src/lib/msun/src/s_modf.c */
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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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- * modf(double x, double *iptr)
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- * return fraction part of x, and return x's integral part in *iptr.
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- * Method:
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- * Bit twiddling.
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- *
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- * Exception:
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- * No exception.
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- */
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-
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-#include "libm.h"
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+#include <math.h>
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+#include <stdint.h>
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double modf(double x, double *iptr)
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{
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- int32_t i0,i1,j0;
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- uint32_t i;
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+ union {double x; uint64_t n;} u = {x};
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+ uint64_t mask;
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+ int e;
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- EXTRACT_WORDS(i0, i1, x);
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- j0 = ((i0>>20) & 0x7ff) - 0x3ff; /* exponent of x */
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- if (j0 < 20) { /* integer part in high x */
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- if (j0 < 0) { /* |x| < 1 */
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- INSERT_WORDS(*iptr, i0 & 0x80000000, 0); /* *iptr = +-0 */
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- return x;
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- }
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- i = 0x000fffff >> j0;
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- if (((i0&i)|i1) == 0) { /* x is integral */
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- uint32_t high;
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- *iptr = x;
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- GET_HIGH_WORD(high, x);
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- INSERT_WORDS(x, high & 0x80000000, 0); /* return +-0 */
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- return x;
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- }
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- INSERT_WORDS(*iptr, i0&~i, 0);
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- return x - *iptr;
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- } else if (j0 > 51) { /* no fraction part */
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- uint32_t high;
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- if (j0 == 0x400) { /* inf/NaN */
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- *iptr = x;
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- return 0.0 / x;
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- }
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+ e = (int)(u.n>>52 & 0x7ff) - 0x3ff;
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+
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+ /* no fractional part */
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+ if (e >= 52) {
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*iptr = x;
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- GET_HIGH_WORD(high, x);
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- INSERT_WORDS(x, high & 0x80000000, 0); /* return +-0 */
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- return x;
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- } else { /* fraction part in low x */
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- i = (uint32_t)0xffffffff >> (j0 - 20);
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- if ((i1&i) == 0) { /* x is integral */
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- uint32_t high;
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- *iptr = x;
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- GET_HIGH_WORD(high, x);
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- INSERT_WORDS(x, high & 0x80000000, 0); /* return +-0 */
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+ if (e == 0x400 && u.n<<12 != 0) /* nan */
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return x;
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- }
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- INSERT_WORDS(*iptr, i0, i1&~i);
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- return x - *iptr;
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+ u.n &= (uint64_t)1<<63;
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+ return u.x;
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+ }
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+
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+ /* no integral part*/
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+ if (e < 0) {
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+ u.n &= (uint64_t)1<<63;
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+ *iptr = u.x;
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+ return x;
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+ }
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+
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+ mask = (uint64_t)-1>>12 >> e;
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+ if ((u.n & mask) == 0) {
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+ *iptr = x;
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+ u.n &= (uint64_t)1<<63;
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+ return u.x;
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}
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+ u.n &= ~mask;
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+ *iptr = u.x;
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+ return x - *iptr;
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}
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