Module Name: src
Committed By: maya
Date: Sun Jan 1 19:32:14 UTC 2017
Modified Files:
src/lib/libm/complex: csqrt.c csqrtf.c
Log Message:
compare to zero, instead of using signbit, and be more specific in comment.
-0.0 > 0 is also false. no functional change.
while this is mostly a change to be consistent in style (the rest of the
comparisons aren't done with signbit), it is also a micro-optimization.
with our default compile flags, calls to copysign are libm calls (and a
whole function call!!). this generates more efficient code.
To generate a diff of this commit:
cvs rdiff -u -r1.3 -r1.4 src/lib/libm/complex/csqrt.c \
src/lib/libm/complex/csqrtf.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libm/complex/csqrt.c
diff -u src/lib/libm/complex/csqrt.c:1.3 src/lib/libm/complex/csqrt.c:1.4
--- src/lib/libm/complex/csqrt.c:1.3 Sat Dec 31 20:01:15 2016
+++ src/lib/libm/complex/csqrt.c Sun Jan 1 19:32:14 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: csqrt.c,v 1.3 2016/12/31 20:01:15 maya Exp $ */
+/* $NetBSD: csqrt.c,v 1.4 2017/01/01 19:32:14 maya Exp $ */
/*-
* Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -41,7 +41,10 @@ csqrt(double complex z)
x = creal (z);
y = cimag (z);
- /* Input is a real number that isn't on the branch cut */
+ /*
+ * input is a real number and imaginary part isn't -0.0.
+ * negative zero is on the branch cut.
+ */
if ((y == 0.0) && !signbit(y)) {
if (x == 0.0) {
w = 0.0 + y * I;
@@ -93,9 +96,9 @@ csqrt(double complex z)
t = scale * fabs((0.5 * y) / r);
r *= scale;
}
- if (signbit(y))
- w = t - r * I;
- else
+ if (y > 0)
w = t + r * I;
+ else
+ w = t - r * I;
return w;
}
Index: src/lib/libm/complex/csqrtf.c
diff -u src/lib/libm/complex/csqrtf.c:1.3 src/lib/libm/complex/csqrtf.c:1.4
--- src/lib/libm/complex/csqrtf.c:1.3 Sat Dec 31 22:54:56 2016
+++ src/lib/libm/complex/csqrtf.c Sun Jan 1 19:32:14 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: csqrtf.c,v 1.3 2016/12/31 22:54:56 maya Exp $ */
+/* $NetBSD: csqrtf.c,v 1.4 2017/01/01 19:32:14 maya Exp $ */
/*-
* Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -41,7 +41,10 @@ csqrtf(float complex z)
x = crealf (z);
y = cimagf (z);
- /* Input is a real number that isn't on the branch cut */
+ /*
+ * input is a real number and imaginary part isn't -0.0.
+ * negative zero is on the branch cut.
+ */
if ((y == 0.0f) && !signbit(y)) {
if (x < 0.0f) {
w = 0.0f + sqrtf(-x) * I;
@@ -93,9 +96,9 @@ csqrtf(float complex z)
r *= scale;
}
- if (signbit(y))
- w = t - r * I;
- else
+ if (y > 0)
w = t + r * I;
+ else
+ w = t - r * I;
return w;
}
