auto import from //depot/cupcake/@135843
diff --git a/libm/src/s_truncl.c b/libm/src/s_truncl.c
new file mode 100644
index 0000000..39926a5
--- /dev/null
+++ b/libm/src/s_truncl.c
@@ -0,0 +1,68 @@
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ *
+ * From: @(#)s_floor.c 5.1 93/09/24
+ */
+
+#ifndef lint
+static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_truncl.c,v 1.4 2005/04/28 19:45:55 stefanf Exp $";
+#endif
+
+/*
+ * truncl(x)
+ * Return x rounded toward 0 to integral value
+ * Method:
+ * Bit twiddling.
+ * Exception:
+ * Inexact flag raised if x not equal to truncl(x).
+ */
+
+#include <float.h>
+#include <math.h>
+#include <stdint.h>
+
+#include "fpmath.h"
+
+#ifdef LDBL_IMPLICIT_NBIT
+#define MANH_SIZE (LDBL_MANH_SIZE + 1)
+#else
+#define MANH_SIZE LDBL_MANH_SIZE
+#endif
+
+static const long double huge = 1.0e300;
+
+long double
+truncl(long double x)
+{
+ union IEEEl2bits u = { .e = x };
+ int e = u.bits.exp - LDBL_MAX_EXP + 1;
+
+ if (e < MANH_SIZE - 1) {
+ if (e < 0) { /* raise inexact if x != 0 */
+ if (huge + x > 0.0)
+ u.e = 0.0;
+ } else {
+ uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1);
+ if (((u.bits.manh & m) | u.bits.manl) == 0)
+ return (x); /* x is integral */
+ if (huge + x > 0.0) { /* raise inexact flag */
+ u.bits.manh &= ~m;
+ u.bits.manl = 0;
+ }
+ }
+ } else if (e < LDBL_MANT_DIG - 1) {
+ uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1);
+ if ((u.bits.manl & m) == 0)
+ return (x); /* x is integral */
+ if (huge + x > 0.0) /* raise inexact flag */
+ u.bits.manl &= ~m;
+ }
+ return (u.e);
+}