@@ -1,5 +1,8 @@
2016-10-06 Siddhesh Poyarekar <siddhesh@sourceware.org>
+ * sysdeps/ieee754/dbl-64/s_sin.c (reduce_and_compute, do_sincos_1,
+ do_sincos_2, sloww, sloww1): Update comments.
+
* sysdeps/ieee754/dbl-64/s_sincos.c (__sincos): Adjust calls to
do_sincos_1 and do_sincos_2 to pass a boolean shift_quadrant.
@@ -263,9 +263,9 @@ do_sin_slow (double x, double dx, double eps, double *corp)
return res;
}
-/* 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. */
+/* Reduce range of X and compute sin of a + da. When SHIFT_QUADRANT is true,
+ the routine returns the cosine of a + da by rotating the quadrant once and
+ computing the sine of the result. */
static inline double
__always_inline
reduce_and_compute (double x, bool shift_quadrant)
@@ -315,8 +315,8 @@ reduce_sincos_1 (double x, double *a, double *da)
return n;
}
-/* Compute sin (A + DA). cos can be computed by shifting the quadrant N
- clockwise. */
+/* Compute sin (A + DA). cos can be computed by passing SHIFT_QUADRANT as
+ true, which results in shifting the quadrant N clockwise. */
static double
__always_inline
do_sincos_1 (double a, double da, double x, int4 n, bool shift_quadrant)
@@ -387,8 +387,8 @@ reduce_sincos_2 (double x, double *a, double *da)
return n;
}
-/* Compute sin (A + DA). cos can be computed by shifting the quadrant N
- clockwise. */
+/* Compute sin (A + DA). cos can be computed by passing SHIFT_QUADRANT as
+ true, which results in shifting the quadrant N clockwise. */
static double
__always_inline
do_sincos_2 (double a, double da, double x, int4 n, bool shift_quadrant)
@@ -686,14 +686,11 @@ slow2 (double x)
return __mpsin (fabs (x), 0, false);
}
-/***************************************************************************/
-/* Routine compute sin(x+dx) (Double-Length number) where x is small enough*/
-/* to use Taylor series around zero and (x+dx) */
-/* in first or third quarter of unit circle.Routine receive also */
-/* (right argument) the original value of x for computing error of */
-/* result.And if result not accurate enough routine calls mpsin1 or dubsin */
-/***************************************************************************/
-
+/* Compute sin(x + dx) where X is small enough to use Taylor series around zero
+ and (x + dx) in the first or third quarter of the unit circle. ORIG is the
+ original value of X for computing error of the result. If the result is not
+ accurate enough, the routine calls mpsin or dubsin. SHIFT_QUADRANT rotates
+ the unit circle by 1 to compute the cosine instead of sine. */
static inline double
__always_inline
sloww (double x, double dx, double orig, bool shift_quadrant)
@@ -748,13 +745,11 @@ sloww (double x, double dx, double orig, bool shift_quadrant)
return shift_quadrant ? __mpcos (orig, 0, true) : __mpsin (orig, 0, true);
}
-/***************************************************************************/
-/* Routine compute sin(x+dx) (Double-Length number) where x in first or */
-/* third quarter of unit circle.Routine receive also (right argument) the */
-/* original value of x for computing error of result.And if result not */
-/* accurate enough routine calls mpsin1 or dubsin */
-/***************************************************************************/
-
+/* Compute sin(x + dx) where X is in the first or third quarter of the unit
+ circle. ORIG is the original value of X for computing error of the result.
+ If the result is not accurate enough, the routine calls mpsin or dubsin.
+ SHIFT_QUADRANT rotates the unit circle by 1 to compute the cosine instead of
+ sine. */
static inline double
__always_inline
sloww1 (double x, double dx, double orig, bool shift_quadrant)