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Consolidate sin/cos computation for large inputs

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Siddhesh Poyarekar 2013-09-19 16:45:27 +05:30
parent 5eea0404a8
commit 6cce25f814
2 changed files with 41 additions and 47 deletions
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5
ChangeLog
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@ -1,5 +1,10 @@
2013-09-19 Siddhesh Poyarekar <siddhesh@redhat.com>
* sysdeps/ieee754/dbl-64/s_sin.c (reduce_and_compute): New
function.
(__sin): Use it.
(__cos): Likewise.
* sysdeps/ieee754/dbl-64/s_sin.c (__sin): Remove redundant
gotos.
(__cos): Likewise.

83
sysdeps/ieee754/dbl-64/s_sin.c
View File

@ -93,6 +93,39 @@ static double csloww (double x, double dx, double orig);
static double csloww1 (double x, double dx, double orig);
static double csloww2 (double x, double dx, double orig, int n);
/* Reduce range of X and compute sin of a + da. K is the amount by which to
rotate the quadrants. This allows us to use the same routine to compute cos
by simply rotating the quadrants by 1. */
static inline double
__always_inline
reduce_and_compute (double x, double a, double da, unsigned int k)
{
double retval = 0;
unsigned int n = __branred (x, &a, &da);
k = (n + k) % 4;
switch (k)
{
case 0:
if (a * a < 0.01588)
retval = bsloww (a, da, x, n);
else
retval = bsloww1 (a, da, x, n);
break;
case 2:
if (a * a < 0.01588)
retval = bsloww (-a, -da, x, n);
else
retval = bsloww1 (-a, -da, x, n);
break;
case 1:
case 3:
retval = bsloww2 (a, da, x, n);
break;
}
return retval;
}
/*******************************************************************/
/* An ultimate sin routine. Given an IEEE double machine number x */
/* it computes the correctly rounded (to nearest) value of sin(x) */
@ -366,29 +399,7 @@ __sin (double x)
/* -----------------281474976710656 <|x| <2^1024----------------------------*/
else if (k < 0x7ff00000)
{
n = __branred (x, &a, &da);
switch (n)
{
case 0:
if (a * a < 0.01588)
retval = bsloww (a, da, x, n);
else
retval = bsloww1 (a, da, x, n);
break;
case 2:
if (a * a < 0.01588)
retval = bsloww (-a, -da, x, n);
else
retval = bsloww1 (-a, -da, x, n);
break;
case 1:
case 3:
retval = bsloww2 (a, da, x, n);
break;
}
} /* else if (k < 0x7ff00000 ) */
retval = reduce_and_compute (x, a, da, 0);
/*--------------------- |x| > 2^1024 ----------------------------------*/
else
@ -684,31 +695,9 @@ __cos (double x)
}
} /* else if (k < 0x42F00000 ) */
/* 281474976710656 <|x| <2^1024 */
else if (k < 0x7ff00000)
{ /* 281474976710656 <|x| <2^1024 */
n = __branred (x, &a, &da);
switch (n)
{
case 1:
if (a * a < 0.01588)
retval = bsloww (-a, -da, x, n);
else
retval = bsloww1 (-a, -da, x, n);
break;
case 3:
if (a * a < 0.01588)
retval = bsloww (a, da, x, n);
else
retval = bsloww1 (a, da, x, n);
break;
case 0:
case 2:
retval = bsloww2 (a, da, x, n);
break;
}
} /* else if (k < 0x7ff00000 ) */
retval = reduce_and_compute (x, a, da, 1);
else
{