Skia Compute core files

Bug: skia:
Change-Id: I4bba49cf20eff013e581800a3f114c85acd8498c
Reviewed-on: https://skia-review.googlesource.com/135782
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/src/compute/common/util.c b/src/compute/common/util.c
new file mode 100644
index 0000000000..69710125a3
--- /dev/null
+++ b/src/compute/common/util.c
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ */
+
+#include <intrin.h> 
+
+//
+//
+//
+
+#include "util.h"
+
+//
+//
+//
+
+bool
+is_pow2_u32(uint32_t n)
+{
+  return (n & (n-1)) == 0;
+}
+
+//
+//
+//
+
+uint32_t
+pow2_ru_u32(uint32_t n)
+{
+  n--;
+  n |= n >> 1;
+  n |= n >> 2;
+  n |= n >> 4;
+  n |= n >> 8;
+  n |= n >> 16;
+  n++;
+
+  return n;
+}
+
+//
+//
+//
+
+uint32_t
+pow2_rd_u32(uint32_t n)
+{
+  return 1u << msb_idx_u32(n);
+}
+
+//
+// ASSUMES NON-ZERO
+//
+
+uint32_t
+msb_idx_u32(uint32_t n)
+{
+
+#ifdef _MSC_VER
+
+  uint32_t index;
+
+  _BitScanReverse(&index,n);
+
+  return index;
+
+#elif defined(__GNUC__)
+
+#error "BUSTED msb_index()"
+  return 31 - __builtin_clz(mask);
+
+#else
+
+#error "No msb_index()"
+
+#endif
+
+}
+
+//
+//
+//