commit e9158fd9e4920bed5e61a7b7a6ef22dfe887209a
author Mike Klein <mtklein@google.com> Thu Oct 10 13:40:35 2019 -0500
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Mon Oct 14 14:52:48 2019 +0000
tree 8ed7fce3f0aa4406121624247d2e886d37de7259
parent ed9daeb11a9887e8e2ed3b85ee5ca778a2d09512

precompute log2(e)

Kind of a freebie.  No interesting change in test case precision.

Change-Id: Ib26ddc5de31f0a456c2c41d92bb457ccdeb12e93
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/247725
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

skcms.cc

diff --git a/skcms.cc b/skcms.cc
index 2cb92ba..4a4fc47 100644
--- a/skcms.cc
+++ b/skcms.cc
@@ -104,8 +104,8 @@
 }
 
 static float expf_(float x) {
-    // TODO: can do better than this...
-    return powf_(2.7182818284590452354f, x);
+    const float log2_e = 1.4426950408889634074f;
+    return exp2f_(log2_e * x);
 }
 
 static float fmaxf_(float x, float y) { return x > y ? x : y; }