diff options
Diffstat (limited to 'sysdeps/libm-ieee754/e_log.c')
| -rw-r--r-- | sysdeps/libm-ieee754/e_log.c | 40 |
1 files changed, 27 insertions, 13 deletions
diff --git a/sysdeps/libm-ieee754/e_log.c b/sysdeps/libm-ieee754/e_log.c index e4e6eab6c5..5b8c7b3ade 100644 --- a/sysdeps/libm-ieee754/e_log.c +++ b/sysdeps/libm-ieee754/e_log.c @@ -9,6 +9,9 @@ * is preserved. * ==================================================== */ +/* Modified by Naohiko Shimizu/Tokai University, Japan 1997/08/25, + for performance improvement on pipelined processors. +*/ #if defined(LIBM_SCCS) && !defined(lint) static char rcsid[] = "$NetBSD: e_log.c,v 1.8 1995/05/10 20:45:49 jtc Exp $"; @@ -67,7 +70,8 @@ static char rcsid[] = "$NetBSD: e_log.c,v 1.8 1995/05/10 20:45:49 jtc Exp $"; #include "math.h" #include "math_private.h" - +#define half Lg[8] +#define two Lg[9] #ifdef __STDC__ static const double #else @@ -76,14 +80,16 @@ static double ln2_hi = 6.93147180369123816490e-01, /* 3fe62e42 fee00000 */ ln2_lo = 1.90821492927058770002e-10, /* 3dea39ef 35793c76 */ 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 */ - + Lg[] = {0.0, + 6.666666666666735130e-01, /* 3FE55555 55555593 */ + 3.999999999940941908e-01, /* 3FD99999 9997FA04 */ + 2.857142874366239149e-01, /* 3FD24924 94229359 */ + 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */ + 1.818357216161805012e-01, /* 3FC74664 96CB03DE */ + 1.531383769920937332e-01, /* 3FC39A09 D078C69F */ + 1.479819860511658591e-01, /* 3FC2F112 DF3E5244 */ + 0.5, + 2.0}; #ifdef __STDC__ static const double zero = 0.0; #else @@ -97,7 +103,7 @@ static double zero = 0.0; double x; #endif { - double hfsq,f,s,z,R,w,t1,t2,dk; + double hfsq,f,s,z,R,w,t1,t2,dk,t11,t12,t21,t22,w2,zw2; int32_t k,hx,i,j; u_int32_t lx; @@ -121,20 +127,28 @@ static double zero = 0.0; if((0x000fffff&(2+hx))<3) { /* |f| < 2**-20 */ if(f==zero) if(k==0) return zero; else {dk=(double)k; return dk*ln2_hi+dk*ln2_lo;} - R = f*f*(0.5-0.33333333333333333*f); + R = f*f*(half-0.33333333333333333*f); if(k==0) return f-R; else {dk=(double)k; return dk*ln2_hi-((R-dk*ln2_lo)-f);} } - s = f/(2.0+f); + s = f/(two+f); dk = (double)k; z = s*s; i = hx-0x6147a; w = z*z; j = 0x6b851-hx; +#ifdef DO_NOT_USE_THIS t1= w*(Lg2+w*(Lg4+w*Lg6)); t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7))); - i |= j; R = t2+t1; +#else + t21 = Lg[5]+w*Lg[7]; w2=w*w; + t22 = Lg[1]+w*Lg[3]; zw2=z*w2; + t11 = Lg[4]+w*Lg[6]; + t12 = w*Lg[2]; + R = t12 + w2*t11 + z*t22 + zw2*t21; +#endif + i |= j; if(i>0) { hfsq=0.5*f*f; if(k==0) return f-(hfsq-s*(hfsq+R)); else |