Novel Rounding Techniques on the NEON Floating-Point Pipeline
David Lutz, Christopher Neal Hinds · 2006
NEON TM Floating-Point (NFP) is a SIMD architecture designed to accelerate 3D Graphics in a handheld environment. Graphics needs less precision than general purpose floating-point, so NFP is single-precision, only supports round-to-nearest-even rounding, and flushes all subnormal inputs and outputs to zero. These simplifications, along with new rounding techniques, enable our first implementation to fit in only half the logic levels of our previous IEEE 754 compliant designs. Parts of the new rounding techniques are based on half-adder form, which allows us to manipulate sums for easy insertion of rounding values and for quick detection of sticky bits. Our rounding is simpler and faster than previous methods for addition, multiplication, and conversion from fixed-point to floatingpoint.