Motorola DSP96002 - Manual (Page 761)

MOTOROLA DSP96002 USER’S MANUAL D-9
Figure D-8. The Data ALU
Automatic Format Conversion Unit
d0.h d0.m d0.l d0
d1
d2
d3
d4
d5
d6
d7
d8
d9
Register File
Control and
Arbitration Unit
Add/Subtract Unit
Multiply Unit
Special Function Unit
Operands Results
X-Data Bus
Y-Data Bus
1. Round to nearest (even): a convergent rounding mode, designed to deliver results without a
rounding bias. In this case the infinite-precision result is rounded to the finite-precision result
which is closest. In the case of an absolute tie, the infinite-precision result is rounded to the
"nearest even" finite precision result, as is illustrated in Table D-2.
2. finite precision result which is closest to zero. Clearly, results are rounded up in this mode when
negative, and down when positive.
3. Round to plus infinity: results are always rounded in the direction of plus infinity, i.e. "up".