diff -ruN /usr/src.bak/lib/msun/Makefile lib/msun/Makefile
--- /usr/src.bak/lib/msun/Makefile	Sun Jul 17 17:47:52 2005
+++ lib/msun/Makefile	Thu Jul 21 15:00:25 2005
@@ -33,7 +33,7 @@
 	e_expf.c e_fmod.c e_fmodf.c e_gamma.c e_gamma_r.c e_gammaf.c \
 	e_gammaf_r.c e_hypot.c e_hypotf.c e_j0.c e_j0f.c e_j1.c e_j1f.c \
 	e_jn.c e_jnf.c e_lgamma.c e_lgamma_r.c e_lgammaf.c e_lgammaf_r.c \
-	e_log.c e_log10.c e_log10f.c e_logf.c e_pow.c e_powf.c e_rem_pio2.c \
+	e_log.c e_log2.c e_log10.c e_log10f.c e_log2f.c e_logf.c e_pow.c e_powf.c e_rem_pio2.c \
 	e_rem_pio2f.c e_remainder.c e_remainderf.c e_scalb.c e_scalbf.c \
 	e_sinh.c e_sinhf.c e_sqrt.c e_sqrtf.c fenv.c \
 	k_cos.c k_cosf.c k_rem_pio2.c k_rem_pio2f.c k_sin.c k_sinf.c \
@@ -114,7 +114,8 @@
 MLINKS+=exp.3 expm1.3 exp.3 log.3 exp.3 log10.3 exp.3 log1p.3 exp.3 pow.3 \
 	exp.3 exp2.3 exp.3 exp2f.3 exp.3 expf.3 \
 	exp.3 expm1f.3 exp.3 logf.3 exp.3 powf.3 \
-	exp.3 log10f.3 exp.3 log1pf.3
+	exp.3 log10f.3 exp.3 log1pf.3 \
+	exp.3 log2.3 exp.3 log2f.3
 MLINKS+=fabs.3 fabsf.3 fabs.3 fabsl.3
 MLINKS+=fdim.3 fdimf.3 fdim.3 fdiml.3
 MLINKS+=feclearexcept.3 fegetexceptflag.3 feclearexcept.3 feraiseexcept.3 \
diff -ruN /usr/src.bak/lib/msun/man/exp.3 lib/msun/man/exp.3
--- /usr/src.bak/lib/msun/man/exp.3	Sun Jul 17 17:47:50 2005
+++ lib/msun/man/exp.3	Thu Jul 21 15:00:54 2005
@@ -45,6 +45,8 @@
 .Nm expm1f ,
 .Nm log ,
 .Nm logf ,
+.Nm log2,
+.Nm log2f,
 .Nm log10 ,
 .Nm log10f ,
 .Nm log1p ,
@@ -73,6 +75,10 @@
 .Ft float
 .Fn logf "float x"
 .Ft double
+.Fn log2 "double x"
+.Ft float
+.Fn log2f "float x"
+.Ft double
 .Fn log10 "double x"
 .Ft float
 .Fn log10f "float x"
@@ -114,6 +120,14 @@
 .Fn logf
 functions compute the value of the natural logarithm of argument
 .Fa x .
+.Pp
+The
+.Fn log2
+and the
+.Fn log2f
+functions compute the value of the logarithm of argument
+.Fa x
+to base 2.
 .Pp
 The
 .Fn log10
diff -ruN /usr/src.bak/lib/msun/src/e_log2.c lib/msun/src/e_log2.c
--- /usr/src.bak/lib/msun/src/e_log2.c	Thu Jan  1 03:00:00 1970
+++ lib/msun/src/e_log2.c	Thu Jul 21 15:12:49 2005
@@ -0,0 +1,79 @@
+
+/* @(#)e_log.c 1.3 95/01/18 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+
+#ifndef lint
+static char rcsid[] = "$FreeBSD$";
+#endif
+
+#include "math.h"
+#include "math_private.h"
+
+static const double
+ln2 = 0.6931471805599452862268,
+two54   =  1.80143985094819840000e+16,  /* 43500000 00000000 */
+Lg1 = 6.666666666666735130e-01,  /* 3FE55555 55555593 */
+Lg2 = 3.999999999940941908e-01,  /* 3FD99999 9997FA04 */
+Lg3 = 2.857142874366239149e-01,  /* 3FD24924 94229359 */
+Lg4 = 2.222219843214978396e-01,  /* 3FCC71C5 1D8E78AF */
+Lg5 = 1.818357216161805012e-01,  /* 3FC74664 96CB03DE */
+Lg6 = 1.531383769920937332e-01,  /* 3FC39A09 D078C69F */
+Lg7 = 1.479819860511658591e-01;  /* 3FC2F112 DF3E5244 */
+
+static const double zero   =  0.0;
+
+double
+__ieee754_log2(double x)
+{
+	double hfsq,f,s,z,R,w,t1,t2,dk;
+	int32_t k,hx,i,j;
+	u_int32_t lx;
+
+	EXTRACT_WORDS(hx,lx,x);
+
+	k=0;
+	if (hx < 0x00100000) {			/* x < 2**-1022  */
+	    if (((hx&0x7fffffff)|lx)==0) 
+		return -two54/zero;		/* log(+-0)=-inf */
+	    if (hx<0) return (x-x)/zero;	/* log(-#) = NaN */
+	    k -= 54; x *= two54; /* subnormal number, scale up x */
+	    GET_HIGH_WORD(hx,x);
+	} 
+	if (hx >= 0x7ff00000) return x+x;
+	k += (hx>>20)-1023;
+	hx &= 0x000fffff;
+	i = (hx+0x95f64)&0x100000;
+	SET_HIGH_WORD(x,hx|(i^0x3ff00000));	/* normalize x or x/2 */
+	k += (i>>20);
+	f = x-1.0;
+	dk = (double)k;
+	if((0x000fffff&(2+hx))<3) {	/* |f| < 2**-20 */
+	    if (f==zero) 
+		    return (dk);
+	    R = f*f*(0.5-0.33333333333333333*f);
+	    return (dk-(R-f)/ln2);
+	}
+ 	s = f/(2.0+f); 
+	z = s*s;
+	i = hx-0x6147a;
+	w = z*z;
+	j = 0x6b851-hx;
+	t1= w*(Lg2+w*(Lg4+w*Lg6)); 
+	t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7))); 
+	i |= j;
+	R = t2+t1;
+	if(i>0) {
+	    hfsq=0.5*f*f;
+	    return (dk-(hfsq-s*(hfsq+R)-f)/ln2);
+	} else
+		return (dk-((s*(f-R))-f)/ln2);
+}
diff -ruN /usr/src.bak/lib/msun/src/e_log2f.c lib/msun/src/e_log2f.c
--- /usr/src.bak/lib/msun/src/e_log2f.c	Thu Jan  1 03:00:00 1970
+++ lib/msun/src/e_log2f.c	Thu Jul 21 14:43:57 2005
@@ -0,0 +1,80 @@
+/* e_logf.c -- float version of e_log.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+#ifndef lint
+static char rcsid[] = "$FreeBSD$";
+#endif
+
+#include "math.h"
+#include "math_private.h"
+
+static const float
+ln2 = 0.6931471805599452862268, 
+two25 =    3.355443200e+07,	/* 0x4c000000 */
+Lg1 = 6.6666668653e-01,	/* 3F2AAAAB */
+Lg2 = 4.0000000596e-01,	/* 3ECCCCCD */
+Lg3 = 2.8571429849e-01, /* 3E924925 */
+Lg4 = 2.2222198546e-01, /* 3E638E29 */
+Lg5 = 1.8183572590e-01, /* 3E3A3325 */
+Lg6 = 1.5313838422e-01, /* 3E1CD04F */
+Lg7 = 1.4798198640e-01; /* 3E178897 */
+
+static const float zero   =  0.0;
+
+float
+__ieee754_log2f(float x)
+{
+	float hfsq,f,s,z,R,w,t1,t2,dk;
+	int32_t k,ix,i,j;
+
+	GET_FLOAT_WORD(ix,x);
+
+	k=0;
+	if (ix < 0x00800000) {			/* x < 2**-126  */
+	    if ((ix&0x7fffffff)==0)
+		return -two25/zero;		/* log(+-0)=-inf */
+	    if (ix<0) return (x-x)/zero;	/* log(-#) = NaN */
+	    k -= 25; x *= two25; /* subnormal number, scale up x */
+	    GET_FLOAT_WORD(ix,x);
+	}
+	if (ix >= 0x7f800000) return x+x;
+	k += (ix>>23)-127;
+	ix &= 0x007fffff;
+	i = (ix+(0x95f64<<3))&0x800000;
+	SET_FLOAT_WORD(x,ix|(i^0x3f800000));	/* normalize x or x/2 */
+	k += (i>>23);
+	dk = (float)k;
+	f = x-(float)1.0;
+	if((0x007fffff&(15+ix))<16) {	/* |f| < 2**-20 */
+	    if (f==zero) 
+		    return (dk);
+	    R = f*f*((float)0.5-(float)0.33333333333333333*f);
+	    return (dk-(R-f)/ln2);
+	}
+ 	s = f/((float)2.0+f);
+	z = s*s;
+	i = ix-(0x6147a<<3);
+	w = z*z;
+	j = (0x6b851<<3)-ix;
+	t1= w*(Lg2+w*(Lg4+w*Lg6));
+	t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7)));
+	i |= j;
+	R = t2+t1;
+	if(i>0) {
+	    hfsq=(float)0.5*f*f;
+	    return (dk-(hfsq-s*(hfsq+R)-f)/ln2);
+	} else
+		return (dk-((s*(f-R))-f)/ln2);
+}
diff -ruN /usr/src.bak/lib/msun/src/math.h lib/msun/src/math.h
--- /usr/src.bak/lib/msun/src/math.h	Sun Jul 17 17:47:52 2005
+++ lib/msun/src/math.h	Thu Jul 21 14:25:21 2005
@@ -203,6 +203,7 @@
 double	frexp(double, int *);	/* fundamentally !__pure2 */
 double	ldexp(double, int);
 double	log(double);
+double	log2(double);
 double	log10(double);
 double	modf(double, double *);	/* fundamentally !__pure2 */
 
@@ -314,6 +315,7 @@
 float	ldexpf(float, int);
 float	log10f(float);
 float	log1pf(float);
+float	log2f(float);
 float	logf(float);
 float	modff(float, float *);	/* fundamentally !__pure2 */
 
diff -ruN /usr/src.bak/lib/msun/src/math_private.h lib/msun/src/math_private.h
--- /usr/src.bak/lib/msun/src/math_private.h	Sun Jul 17 17:47:52 2005
+++ lib/msun/src/math_private.h	Thu Jul 21 14:45:31 2005
@@ -176,6 +176,7 @@
 #define	__ieee754_lgamma_r lgamma_r
 #define	__ieee754_gamma_r gamma_r
 #define	__ieee754_log10	log10
+#define	__ieee754_log2	log2
 #define	__ieee754_sinh	sinh
 #define	__ieee754_hypot	hypot
 #define	__ieee754_j0	j0
@@ -202,6 +203,7 @@
 #define	__ieee754_lgammaf_r lgammaf_r
 #define	__ieee754_gammaf_r gammaf_r
 #define	__ieee754_log10f log10f
+#define	__ieee754_log2f	log2f
 #define	__ieee754_sinhf	sinhf
 #define	__ieee754_hypotf hypotf
 #define	__ieee754_j0f	j0f