ios fixes

src/core/SkFloatBits.cpp

 /*
  * Copyright 2011 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 "SkMathPriv.h"
 
@@ skipping 67 matching lines @@
         } else {
             value <<= exp;
         }
         // apply the sign after we check for overflow
         return SkApplySign(value, SkExtractSign(packed));
     } else {
         // apply the sign before we right-shift
         value = SkApplySign(value, SkExtractSign(packed));
         exp = -exp;
         if (exp > 25) {   // underflow
+#ifdef SK_BUILD_FOR_IOS
+            if (exp > 149) return 0;

[reed1, 2014/07/10 18:39:39]

Can we perhaps encapsulate this in a helper function, like handle_underflow.
Then we could #ifdef and adda  comment with a bug or test reference to help
explain why.

[caryclark, 2014/07/10 21:07:03]

I commented and gave it a platform independent #define, but it's unclear to me
how to isolate this in a helper function.

+#else
             exp = 25;
+#endif
         }
         // int add = 0;
         return value >> exp;
     }
 }
 
 // same as (int)floor(float + 0.5)
 int32_t SkFloatBits_toIntRound(int32_t packed) {
     // curse you negative 0
     if ((packed << 1) == 0) {
@@ skipping 39 matching lines @@
         } else {
             value <<= exp;
         }
         // apply the sign after we check for overflow
         return SkApplySign(value, SkExtractSign(packed));
     } else {
         // apply the sign before we right-shift
         value = SkApplySign(value, SkExtractSign(packed));
         exp = -exp;
         if (exp > 25) {   // underflow
+#ifdef SK_BUILD_FOR_IOS
+            if (exp > 149) return 0;
+            return 0 < value;
+#else
             exp = 25;
+#endif
         }
         int add = (1 << exp) - 1;
         return (value + add) >> exp;
     }
 }
 
 float SkIntToFloatCast(int32_t value) {
     if (0 == value) {
         return 0;
     }
@@ skipping 38 matching lines @@
     value = SkApplySign(value, sign);
 
     int zeros = SkCLZ(value << 8);
     value <<= zeros;
     shift -= zeros;
 
     SkFloatIntUnion data;
     data.fSignBitInt = (sign << 31) | (shift << 23) | (value & ~MATISSA_MAGIC_BIG);
     return data.fFloat;
 }