diff options
Diffstat (limited to 'sysdeps/libm-ieee754/e_asin.c')
| -rw-r--r-- | sysdeps/libm-ieee754/e_asin.c | 48 |
1 files changed, 35 insertions, 13 deletions
diff --git a/sysdeps/libm-ieee754/e_asin.c b/sysdeps/libm-ieee754/e_asin.c index 09d06a9158..65dc318db3 100644 --- a/sysdeps/libm-ieee754/e_asin.c +++ b/sysdeps/libm-ieee754/e_asin.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_asin.c,v 1.9 1995/05/12 04:57:22 jtc Exp $"; @@ -47,28 +50,27 @@ static char rcsid[] = "$NetBSD: e_asin.c,v 1.9 1995/05/12 04:57:22 jtc Exp $"; #include "math.h" #include "math_private.h" - +#define one qS[0] #ifdef __STDC__ static const double #else static double #endif -one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */ huge = 1.000e+300, pio2_hi = 1.57079632679489655800e+00, /* 0x3FF921FB, 0x54442D18 */ pio2_lo = 6.12323399573676603587e-17, /* 0x3C91A626, 0x33145C07 */ pio4_hi = 7.85398163397448278999e-01, /* 0x3FE921FB, 0x54442D18 */ /* coefficient for R(x^2) */ -pS0 = 1.66666666666666657415e-01, /* 0x3FC55555, 0x55555555 */ -pS1 = -3.25565818622400915405e-01, /* 0xBFD4D612, 0x03EB6F7D */ -pS2 = 2.01212532134862925881e-01, /* 0x3FC9C155, 0x0E884455 */ -pS3 = -4.00555345006794114027e-02, /* 0xBFA48228, 0xB5688F3B */ -pS4 = 7.91534994289814532176e-04, /* 0x3F49EFE0, 0x7501B288 */ -pS5 = 3.47933107596021167570e-05, /* 0x3F023DE1, 0x0DFDF709 */ -qS1 = -2.40339491173441421878e+00, /* 0xC0033A27, 0x1C8A2D4B */ -qS2 = 2.02094576023350569471e+00, /* 0x40002AE5, 0x9C598AC8 */ -qS3 = -6.88283971605453293030e-01, /* 0xBFE6066C, 0x1B8D0159 */ -qS4 = 7.70381505559019352791e-02; /* 0x3FB3B8C5, 0xB12E9282 */ +pS[] = {1.66666666666666657415e-01, /* 0x3FC55555, 0x55555555 */ + -3.25565818622400915405e-01, /* 0xBFD4D612, 0x03EB6F7D */ + 2.01212532134862925881e-01, /* 0x3FC9C155, 0x0E884455 */ + -4.00555345006794114027e-02, /* 0xBFA48228, 0xB5688F3B */ + 7.91534994289814532176e-04, /* 0x3F49EFE0, 0x7501B288 */ + 3.47933107596021167570e-05}, /* 0x3F023DE1, 0x0DFDF709 */ +qS[] = {1.0, -2.40339491173441421878e+00, /* 0xC0033A27, 0x1C8A2D4B */ + 2.02094576023350569471e+00, /* 0x40002AE5, 0x9C598AC8 */ + -6.88283971605453293030e-01, /* 0xBFE6066C, 0x1B8D0159 */ + 7.70381505559019352791e-02}; /* 0x3FB3B8C5, 0xB12E9282 */ #ifdef __STDC__ double __ieee754_asin(double x) @@ -77,7 +79,7 @@ qS4 = 7.70381505559019352791e-02; /* 0x3FB3B8C5, 0xB12E9282 */ double x; #endif { - double t,w,p,q,c,r,s; + double t,w,p,q,c,r,s,p1,p2,p3,q1,q2,q3,z2,z4,z6; int32_t hx,ix; GET_HIGH_WORD(hx,x); ix = hx&0x7fffffff; @@ -93,8 +95,18 @@ qS4 = 7.70381505559019352791e-02; /* 0x3FB3B8C5, 0xB12E9282 */ if(huge+x>one) return x;/* return x with inexact if x!=0*/ } else { t = x*x; +#ifdef DO_NOT_USE_THIS p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5))))); q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4))); +#else + p1 = t*pS[0]; z2=t*t; + p2 = pS[1]+t*pS[2]; z4=z2*z2; + p3 = pS[3]+t*pS[4]; z6=z4*z2; + q1 = one+t*qS[1]; + q2 = qS[2]+t*qS[3]; + p = p1 + z2*p2 + z4*p3 + z6*pS[5]; + q = q1 + z2*q2 + z4*qS[4]; +#endif w = p/q; return x+x*w; } @@ -102,8 +114,18 @@ qS4 = 7.70381505559019352791e-02; /* 0x3FB3B8C5, 0xB12E9282 */ /* 1> |x|>= 0.5 */ w = one-fabs(x); t = w*0.5; +#ifdef DO_NOT_USE_THIS p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5))))); q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4))); +#else + p1 = t*pS[0]; z2=t*t; + p2 = pS[1]+t*pS[2]; z4=z2*z2; + p3 = pS[3]+t*pS[4]; z6=z4*z2; + q1 = one+t*qS[1]; + q2 = qS[2]+t*qS[3]; + p = p1 + z2*p2 + z4*p3 + z6*pS[5]; + q = q1 + z2*q2 + z4*qS[4]; +#endif s = __ieee754_sqrt(t); if(ix>=0x3FEF3333) { /* if |x| > 0.975 */ w = p/q; |