diff options
| -rw-r--r-- | ChangeLog | 4 | ||||
| -rw-r--r-- | sysdeps/ieee754/flt-32/s_tanf.c | 29 |
2 files changed, 32 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog index a22301f323..2c902f2b98 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,7 @@ +2018-08-23 Wilco Dijkstra <wdijkstr@arm.com> + + * sysdeps/ieee754/flt-32/s_tanf.c (__tanf): Use fast range reduction. + 2018-08-22 DJ Delorie <dj@redhat.com> * Makefile (testroot.pristine): New rules to initialize the diff --git a/sysdeps/ieee754/flt-32/s_tanf.c b/sysdeps/ieee754/flt-32/s_tanf.c index ba3af54913..fd104103ad 100644 --- a/sysdeps/ieee754/flt-32/s_tanf.c +++ b/sysdeps/ieee754/flt-32/s_tanf.c @@ -21,6 +21,33 @@ static char rcsid[] = "$NetBSD: s_tanf.c,v 1.4 1995/05/10 20:48:20 jtc Exp $"; #include <math.h> #include <math_private.h> #include <libm-alias-float.h> +#include "s_sincosf.h" + +/* Reduce range of X to a multiple of PI/2. The modulo result is between + -PI/4 and PI/4 and returned as a high part y[0] and a low part y[1]. + The low bit in the return value indicates the first or 2nd half of tanf. */ +static inline int32_t +rem_pio2f (float x, float *y) +{ + double dx = x; + int n; + const sincos_t *p = &__sincosf_table[0]; + + if (__glibc_likely (abstop12 (x) < abstop12 (120.0f))) + dx = reduce_fast (dx, p, &n); + else + { + uint32_t xi = asuint (x); + int sign = xi >> 31; + + dx = reduce_large (xi, &n); + dx = sign ? -dx : dx; + } + + y[0] = dx; + y[1] = dx - y[0]; + return n; +} float __tanf(float x) { @@ -42,7 +69,7 @@ float __tanf(float x) /* argument reduction needed */ else { - n = __ieee754_rem_pio2f(x,y); + n = rem_pio2f(x,y); return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /* 1 -- n even -1 -- n odd */ } |