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authorZack Weinberg <zackw@panix.com>2017-06-08 15:39:03 -0400
committerZack Weinberg <zackw@panix.com>2017-06-08 15:39:03 -0400
commit5046dbb4a7eba5eccfd258f92f4735c9ffc8d069 (patch)
tree4470480d904b65cf14ca524f96f79eca818c3eaf /REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/s_scalbn.c
parent199fc19d3aaaf57944ef036e15904febe877fc93 (diff)
downloadglibc-zack/build-layout-experiment.tar.gz
Prepare for radical source tree reorganization.zack/build-layout-experiment
All top-level files and directories are moved into a temporary storage directory, REORG.TODO, except for files that will certainly still exist in their current form at top level when we're done (COPYING, COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which are moved to the new directory OldChangeLogs, instead), and the generated file INSTALL (which is just deleted; in the new order, there will be no generated files checked into version control).
Diffstat (limited to 'REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/s_scalbn.c')
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diff --git a/REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/s_scalbn.c b/REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/s_scalbn.c
new file mode 100644
index 0000000000..d517a919c8
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+++ b/REORG.TODO/sysdeps/ieee754/dbl-64/wordsize-64/s_scalbn.c
@@ -0,0 +1,60 @@
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/*
+ * scalbn (double x, int n)
+ * scalbn(x,n) returns x* 2**n computed by exponent
+ * manipulation rather than by actually performing an
+ * exponentiation or a multiplication.
+ */
+
+#include <math.h>
+#include <math_private.h>
+
+static const double
+two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
+twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
+huge = 1.0e+300,
+tiny = 1.0e-300;
+
+double
+__scalbn (double x, int n)
+{
+ int64_t ix;
+ int64_t k;
+ EXTRACT_WORDS64(ix,x);
+ k = (ix >> 52) & 0x7ff; /* extract exponent */
+ if (__builtin_expect(k==0, 0)) { /* 0 or subnormal x */
+ if ((ix & UINT64_C(0xfffffffffffff))==0) return x; /* +-0 */
+ x *= two54;
+ EXTRACT_WORDS64(ix,x);
+ k = ((ix >> 52) & 0x7ff) - 54;
+ }
+ if (__builtin_expect(k==0x7ff, 0)) return x+x; /* NaN or Inf */
+ if (__builtin_expect(n< -50000, 0))
+ return tiny*__copysign(tiny,x); /*underflow*/
+ if (__builtin_expect(n> 50000 || k+n > 0x7fe, 0))
+ return huge*__copysign(huge,x); /* overflow */
+ /* Now k and n are bounded we know that k = k+n does not
+ overflow. */
+ k = k+n;
+ if (__builtin_expect(k > 0, 1)) /* normal result */
+ {INSERT_WORDS64(x,(ix&UINT64_C(0x800fffffffffffff))|(k<<52));
+ return x;}
+ if (k <= -54)
+ return tiny*__copysign(tiny,x); /*underflow*/
+ k += 54; /* subnormal result */
+ INSERT_WORDS64(x,(ix&INT64_C(0x800fffffffffffff))|(k<<52));
+ return x*twom54;
+}
+#ifdef NO_LONG_DOUBLE
+strong_alias (__scalbn, __scalbnl)
+#endif