auto import from //depot/cupcake/@135843
diff --git a/libc/bionic/ldexp.c b/libc/bionic/ldexp.c
new file mode 100644
index 0000000..ec1f3dd
--- /dev/null
+++ b/libc/bionic/ldexp.c
@@ -0,0 +1,122 @@
+/* @(#)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>
+
+#include <sys/types.h>
+#include <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;
+}