Commit: 13e075600ac985bb0d5ff171d7554a4e465db829
Author: Sergey Sharybin
Date: Thu Feb 23 14:42:06 2017 +0100
Branches: master
https://developer.blender.org/rB13e075600ac985bb0d5ff171d7554a4e465db829
Cycles: Add utility function to convert float to half
handles overflow and underflow, but not NaN/inf.
===================================================================
M intern/cycles/util/util_half.h
===================================================================
diff --git a/intern/cycles/util/util_half.h b/intern/cycles/util/util_half.h
index 5db3384cda..7285c6ef60 100644
--- a/intern/cycles/util/util_half.h
+++ b/intern/cycles/util/util_half.h
@@ -110,6 +110,28 @@ ccl_device_inline float4 half4_to_float4(half4 h)
return f;
}
+ccl_device_inline half float_to_half(float f)
+{
+ const uint u = __float_as_uint(f);
+ /* Sign bit, shifted to it's position. */
+ uint sign_bit = u & 0x80000000;
+ sign_bit >>= 16;
+ /* Exponent. */
+ uint exponent_bits = u & 0x7f800000;
+ /* Non-sign bits. */
+ uint value_bits = u & 0x7fffffff;
+ value_bits >>= 13; /* Align mantissa on MSB. */
+ value_bits -= 0x1c000; /* Adjust bias. */
+ /* Flush-to-zero. */
+ value_bits = (exponent_bits < 0x38800000) ? 0 : value_bits;
+ /* Clamp-to-max. */
+ value_bits = (exponent_bits > 0x47000000) ? 0x7bff : value_bits;
+ /* Denormals-as-zero. */
+ value_bits = (exponent_bits == 0 ? 0 : value_bits);
+ /* Re-insert sign bit and return. */
+ return (value_bits | sign_bit);
+}
+
#endif
#endif
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