path ops work in progress

src/pathops/SkPathOpsTypes.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkFloatBits.h"
 #include "SkPathOpsTypes.h"
 
-
-
 // from http://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/
 // FIXME: move to SkFloatBits.h
 static bool equal_ulps(float a, float b, int epsilon) {
-    SkFloatIntUnion floatIntA, floatIntB;
-    floatIntA.fFloat = a;
-    floatIntB.fFloat = b;
-    // Different signs means they do not match.
-    if ((floatIntA.fSignBitInt < 0) != (floatIntB.fSignBitInt < 0)) {
-        // Check for equality to make sure +0 == -0
-        return a == b;
+    if (!SkScalarIsFinite(a) || !SkScalarIsFinite(b)) {
+        return false;
     }
+    int aBits = SkFloatAs2sCompliment(a);
+    int bBits = SkFloatAs2sCompliment(b);
     // Find the difference in ULPs.
-    int ulpsDiff = abs(floatIntA.fSignBitInt - floatIntB.fSignBitInt);
-    return ulpsDiff <= epsilon;
+    return aBits < bBits + epsilon && bBits < aBits + epsilon;
+}
+
+static bool not_equal_ulps(float a, float b, int epsilon) {
+    if (!SkScalarIsFinite(a) || !SkScalarIsFinite(b)) {
+        return false;
+    }
+    int aBits = SkFloatAs2sCompliment(a);
+    int bBits = SkFloatAs2sCompliment(b);
+    // Find the difference in ULPs.
+    return aBits >= bBits + epsilon || bBits >= aBits + epsilon;
 }
 
 static bool less_ulps(float a, float b, int epsilon) {
-    SkFloatIntUnion floatIntA, floatIntB;
-    floatIntA.fFloat = a;
-    floatIntB.fFloat = b;
-    // Check different signs with float epsilon since we only care if they're both close to 0.
-    if ((floatIntA.fSignBitInt < 0) != (floatIntB.fSignBitInt < 0)) {
-        return a <= b + FLT_EPSILON * epsilon;
+    if (!SkScalarIsFinite(a) || !SkScalarIsFinite(b)) {
+        return false;
     }
+    int aBits = SkFloatAs2sCompliment(a);
+    int bBits = SkFloatAs2sCompliment(b);
     // Find the difference in ULPs.
-    return floatIntA.fSignBitInt <= floatIntB.fSignBitInt + epsilon;
+    return aBits <= bBits - epsilon;
+}
+
+static bool less_or_equal_ulps(float a, float b, int epsilon) {
+    if (!SkScalarIsFinite(a) || !SkScalarIsFinite(b)) {
+        return false;
+    }
+    int aBits = SkFloatAs2sCompliment(a);
+    int bBits = SkFloatAs2sCompliment(b);
+    // Find the difference in ULPs.
+    return aBits < bBits + epsilon;
+}
+
+// equality using the same error term as between
+bool AlmostBequalUlps(float a, float b) {
+    const int UlpsEpsilon = 2;
+    return equal_ulps(a, b, UlpsEpsilon);
 }
 
 bool AlmostEqualUlps(float a, float b) {
     const int UlpsEpsilon = 16;
     return equal_ulps(a, b, UlpsEpsilon);
 }
 
+bool NotAlmostEqualUlps(float a, float b) {
+    const int UlpsEpsilon = 16;
+    return not_equal_ulps(a, b, UlpsEpsilon);
+}
+
 bool RoughlyEqualUlps(float a, float b) {
     const int UlpsEpsilon = 256;
     return equal_ulps(a, b, UlpsEpsilon);
 }
 
 bool AlmostBetweenUlps(float a, float b, float c) {
-    const int UlpsEpsilon = 1;
-    return a <= c ? less_ulps(a, b, UlpsEpsilon) && less_ulps(b, c, UlpsEpsilon)
-        : less_ulps(b, a, UlpsEpsilon) && less_ulps(c, b, UlpsEpsilon);
+    const int UlpsEpsilon = 2;
+    return a <= c ? less_or_equal_ulps(a, b, UlpsEpsilon) && less_or_equal_ulps(b, c, UlpsEpsilon)
+        : less_or_equal_ulps(b, a, UlpsEpsilon) && less_or_equal_ulps(c, b, UlpsEpsilon);
+}
+
+bool AlmostLessUlps(float a, float b) {
+    const int UlpsEpsilon = 16;
+    return less_ulps(a, b, UlpsEpsilon);
+}
+
+bool AlmostLessOrEqualUlps(float a, float b) {
+    const int UlpsEpsilon = 16;
+    return less_or_equal_ulps(a, b, UlpsEpsilon);
 }
 
 int UlpsDistance(float a, float b) {
+    if (!SkScalarIsFinite(a) || !SkScalarIsFinite(b)) {
+        return SK_MaxS32;
+    }
     SkFloatIntUnion floatIntA, floatIntB;
     floatIntA.fFloat = a;
     floatIntB.fFloat = b;
     // Different signs means they do not match.
     if ((floatIntA.fSignBitInt < 0) != (floatIntB.fSignBitInt < 0)) {
         // Check for equality to make sure +0 == -0
         return a == b ? 0 : SK_MaxS32;
     }
     // Find the difference in ULPs.
     return abs(floatIntA.fSignBitInt - floatIntB.fSignBitInt);
@@ skipping 28 matching lines @@
 double SkDCubeRoot(double x) {
     if (approximately_zero_cubed(x)) {
         return 0;
     }
     double result = halley_cbrt3d(fabs(x));
     if (x < 0) {
         result = -result;
     }
     return result;
 }