Privatization:
move SkFDot.h to private
move parts of SkMath.h into SkMathPriv.h
Review URL: https://codereview.appspot.com/6461045
git-svn-id: http://skia.googlecode.com/svn/trunk@4997 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkMathPriv.h b/src/core/SkMathPriv.h
new file mode 100644
index 0000000..055acc4
--- /dev/null
+++ b/src/core/SkMathPriv.h
@@ -0,0 +1,94 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkMathPriv_DEFINED
+#define SkMathPriv_DEFINED
+
+#include "SkMath.h"
+
+/** Returns -1 if n < 0, else returns 0
+ */
+#define SkExtractSign(n) ((int32_t)(n) >> 31)
+
+/** If sign == -1, returns -n, else sign must be 0, and returns n.
+ Typically used in conjunction with SkExtractSign().
+ */
+static inline int32_t SkApplySign(int32_t n, int32_t sign) {
+ SkASSERT(sign == 0 || sign == -1);
+ return (n ^ sign) - sign;
+}
+
+/** Return x with the sign of y */
+static inline int32_t SkCopySign32(int32_t x, int32_t y) {
+ return SkApplySign(x, SkExtractSign(x ^ y));
+}
+
+/** Given a positive value and a positive max, return the value
+ pinned against max.
+ Note: only works as long as max - value doesn't wrap around
+ @return max if value >= max, else value
+ */
+static inline unsigned SkClampUMax(unsigned value, unsigned max) {
+#ifdef SK_CPU_HAS_CONDITIONAL_INSTR
+ if (value > max) {
+ value = max;
+ }
+ return value;
+#else
+ int diff = max - value;
+ // clear diff if diff is positive
+ diff &= diff >> 31;
+
+ return value + diff;
+#endif
+}
+
+/** Computes the 64bit product of a * b, and then shifts the answer down by
+ shift bits, returning the low 32bits. shift must be [0..63]
+ e.g. to perform a fixedmul, call SkMulShift(a, b, 16)
+ */
+int32_t SkMulShift(int32_t a, int32_t b, unsigned shift);
+
+/** Return the integer square root of n, treated as a SkFixed (16.16)
+ */
+#define SkSqrt32(n) SkSqrtBits(n, 15)
+
+/** Return the integer cube root of value, with a bias of bitBias
+ */
+int32_t SkCubeRootBits(int32_t value, int bitBias);
+
+///////////////////////////////////////////////////////////////////////////////
+
+/** Return a*b/255, truncating away any fractional bits. Only valid if both
+ a and b are 0..255
+ */
+static inline U8CPU SkMulDiv255Trunc(U8CPU a, U8CPU b) {
+ SkASSERT((uint8_t)a == a);
+ SkASSERT((uint8_t)b == b);
+ unsigned prod = SkMulS16(a, b) + 1;
+ return (prod + (prod >> 8)) >> 8;
+}
+
+/** Return (a*b)/255, taking the ceiling of any fractional bits. Only valid if
+ both a and b are 0..255. The expected result equals (a * b + 254) / 255.
+ */
+static inline U8CPU SkMulDiv255Ceiling(U8CPU a, U8CPU b) {
+ SkASSERT((uint8_t)a == a);
+ SkASSERT((uint8_t)b == b);
+ unsigned prod = SkMulS16(a, b) + 255;
+ return (prod + (prod >> 8)) >> 8;
+}
+
+/** Just the rounding step in SkDiv255Round: round(value / 255)
+ */
+static inline unsigned SkDiv255Round(unsigned prod) {
+ prod += 128;
+ return (prod + (prod >> 8)) >> 8;
+}
+
+#endif
+