1 files changed, 21 insertions, 0 deletions

diff --git a/linden/indra/llmath/llmath.h b/linden/indra/llmath/llmath.h
index dbd825d..dd44e0c 100644
--- a/linden/indra/llmath/llmath.h
+++ b/linden/indra/llmath/llmath.h
@@ -99,6 +99,27 @@ inline BOOL is_approx_equal(F32 x, F32 y)
         return (abs((S32) ((U32&)x - (U32&)y) ) < COMPARE_MANTISSA_UP_TO_BIT);
 }
 
+inline BOOL is_approx_equal_fraction(F32 x, F32 y, U32 frac_bits)
+{
+        BOOL ret = TRUE;
+        F32 diff = (F32) fabs(x - y);
+
+        S32 diffInt = (S32) diff;
+        S32 diffFracTolerance = (S32) ((diff - (F32) diffInt) * (1 << frac_bits));
+        
+        // if integer portion is not equal, not enough bits were used for packing
+        // so error out since either the use case is not correct OR there is
+        // an issue with pack/unpack. should fail in either case.
+        // for decimal portion, make sure that the delta is no more than 1
+        // based on the number of bits used for packing decimal portion.
+        if (diffInt != 0 || diffFracTolerance > 1)
+        {
+                ret = FALSE;
+        }
+
+        return ret;
+}
+
 inline S32 llabs(const S32 a)
 {
         return S32(labs(a));