path ops work in progress

src/pathops/SkPathOpsTypes.cpp

Index: src/pathops/SkPathOpsTypes.cpp
diff --git a/src/pathops/SkPathOpsTypes.cpp b/src/pathops/SkPathOpsTypes.cpp
index 2d7388b8822329f48ac91d512082f476835b2901..df73d11ce44e0122abf84f86318ef8011444f0b3 100644
--- a/src/pathops/SkPathOpsTypes.cpp
+++ b/src/pathops/SkPathOpsTypes.cpp
@@ -7,12 +7,30 @@
 #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.
@@ -23,6 +41,19 @@ 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.
@@ -33,6 +64,9 @@ 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.
@@ -43,6 +77,9 @@ 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.
@@ -55,6 +92,11 @@ bool AlmostBequalUlps(float a, float b) {
     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);
@@ -65,6 +107,11 @@ bool NotAlmostEqualUlps(float a, float b) {
     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);