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"
 
+static bool arguments_denormalized(float a, float b, int epsilon) {
+    float denomalizedCheck = FLT_EPSILON * epsilon / 2;
+    return fabsf(a) <= denomalizedCheck && fabsf(b) <= denomalizedCheck;
+}
+
 // 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) {
     if (!SkScalarIsFinite(a) || !SkScalarIsFinite(b)) {
         return false;
     }
+    if (arguments_denormalized(a, b, epsilon)) {
+        return true;
+    }
     int aBits = SkFloatAs2sCompliment(a);
     int bBits = SkFloatAs2sCompliment(b);
     // Find the difference in ULPs.
+    return aBits < bBits + epsilon && bBits < aBits + epsilon;
+}
+
+static bool d_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 not_equal_ulps(float a, float b, int epsilon) {
     if (!SkScalarIsFinite(a) || !SkScalarIsFinite(b)) {
         return false;
     }
+    if (arguments_denormalized(a, b, epsilon)) {
+        return false;
+    }
+    int aBits = SkFloatAs2sCompliment(a);
+    int bBits = SkFloatAs2sCompliment(b);
+    // Find the difference in ULPs.
+    return aBits >= bBits + epsilon || bBits >= aBits + epsilon;
+}
+
+static bool d_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) {
     if (!SkScalarIsFinite(a) || !SkScalarIsFinite(b)) {
         return false;
     }
+    if (arguments_denormalized(a, b, epsilon)) {
+        return a <= b - FLT_EPSILON * epsilon;
+    }
     int aBits = SkFloatAs2sCompliment(a);
     int bBits = SkFloatAs2sCompliment(b);
     // Find the difference in ULPs.
     return aBits <= bBits - epsilon;
 }
 
 static bool less_or_equal_ulps(float a, float b, int epsilon) {
     if (!SkScalarIsFinite(a) || !SkScalarIsFinite(b)) {
         return false;
     }
+    if (arguments_denormalized(a, b, epsilon)) {
+        return a < b + FLT_EPSILON * epsilon;
+    }
     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 AlmostDequalUlps(float a, float b) {
+    const int UlpsEpsilon = 16;
+    return d_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 NotAlmostDequalUlps(float a, float b) {
+    const int UlpsEpsilon = 16;
+    return d_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 = 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);
 }
@@ skipping 53 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;
 }