git: 85e5714ec795 - stable/13 - Also use the musl scalbn code for ldexp()

[Alex Richardson]

The branch stable/13 has been updated by arichardson:

URL: https://cgit.FreeBSD.org/src/commit/?id=85e5714ec7952851e4232a8fc8354b37c6d94971

commit 85e5714ec7952851e4232a8fc8354b37c6d94971
Author:     Alex Richardson <arichardson at FreeBSD.org>
AuthorDate: 2021-02-25 14:29:44 +0000
Commit:     Alex Richardson <arichardson at FreeBSD.org>
CommitDate: 2021-04-22 09:42:19 +0000

    Also use the musl scalbn code for ldexp()
    
    Instead of copying the code as 00646ca2047305fce32d99edc7a8e6dfd801f3b4
    did, include the implementation with the function name re-defined.
    
    (cherry picked from commit aac21e66f94e0a8ad52c1f8cd8dce50fcdd35cca)
---
 lib/libc/gen/ldexp.c | 126 +++------------------------------------------------
 1 file changed, 6 insertions(+), 120 deletions(-)

diff --git a/lib/libc/gen/ldexp.c b/lib/libc/gen/ldexp.c
index 887f673ee9a5..878271576313 100644
--- a/lib/libc/gen/ldexp.c
+++ b/lib/libc/gen/ldexp.c
@@ -1,123 +1,9 @@
-/* @(#)s_scalbn.c 5.1 93/09/24 */
-/* @(#)fdlibm.h 5.1 93/09/24 */
-/*
- * ====================================================
- * 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.
- * ====================================================
- */
-
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
-#include <sys/types.h>
-#include <machine/endian.h>
-#include <math.h>
-
-/* Bit fiddling routines copied from msun/src/math_private.h,v 1.15 */
-
-#if BYTE_ORDER == BIG_ENDIAN
-
-typedef union
-{
-  double value;
-  struct
-  {
-    u_int32_t msw;
-    u_int32_t lsw;
-  } parts;
-} ieee_double_shape_type;
-
-#endif
-
-#if BYTE_ORDER == LITTLE_ENDIAN
-
-typedef union
-{
-  double value;
-  struct
-  {
-    u_int32_t lsw;
-    u_int32_t msw;
-  } parts;
-} ieee_double_shape_type;
-
-#endif
-
-/* Get two 32 bit ints from a double.  */
-
-#define EXTRACT_WORDS(ix0,ix1,d)				\
-do {								\
-  ieee_double_shape_type ew_u;					\
-  ew_u.value = (d);						\
-  (ix0) = ew_u.parts.msw;					\
-  (ix1) = ew_u.parts.lsw;					\
-} while (0)
-
-/* Get the more significant 32 bit int from a double.  */
-
-#define GET_HIGH_WORD(i,d)					\
-do {								\
-  ieee_double_shape_type gh_u;					\
-  gh_u.value = (d);						\
-  (i) = gh_u.parts.msw;						\
-} while (0)
-
-/* Set the more significant 32 bits of a double from an int.  */
-
-#define SET_HIGH_WORD(d,v)					\
-do {								\
-  ieee_double_shape_type sh_u;					\
-  sh_u.value = (d);						\
-  sh_u.parts.msw = (v);						\
-  (d) = sh_u.value;						\
-} while (0)
-
-
-static const double
-two54   =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
-twom54  =  5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
-huge   = 1.0e+300,
-tiny   = 1.0e-300;
-
-static double
-_copysign(double x, double y)
-{
-	u_int32_t hx,hy;
-	GET_HIGH_WORD(hx,x);
-	GET_HIGH_WORD(hy,y);
-	SET_HIGH_WORD(x,(hx&0x7fffffff)|(hy&0x80000000));
-	return x;
-}
-
-double
-ldexp(double x, int n)
-{
-	int32_t k,hx,lx;
-	EXTRACT_WORDS(hx,lx,x);
-        k = (hx&0x7ff00000)>>20;		/* extract exponent */
-        if (k==0) {				/* 0 or subnormal x */
-            if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
-	    x *= two54;
-	    GET_HIGH_WORD(hx,x);
-	    k = ((hx&0x7ff00000)>>20) - 54;
-            if (n< -50000) return tiny*x; 	/*underflow*/
-	    }
-        if (k==0x7ff) return x+x;		/* NaN or Inf */
-        k = k+n;
-        if (k >  0x7fe) return huge*_copysign(huge,x); /* overflow  */
-        if (k > 0) 				/* normal result */
-	    {SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x;}
-        if (k <= -54) {
-            if (n > 50000) 	/* in case integer overflow in n+k */
-		return huge*_copysign(huge,x);	/*overflow*/
-	    else return tiny*_copysign(tiny,x); 	/*underflow*/
-	}
-        k += 54;				/* subnormal result */
-	SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));
-        return x*twom54;
-}
+/*
+ * ldexp() and scalbn() are defined to be identical, but ldexp() lives in libc
+ * for backwards compatibility.
+ */
+#define scalbn ldexp
+#include "../../msun/src/s_scalbn.c"