dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 191

• Manufacturer Part Number: dsp56800e
• Description: 16-bit Digital Signal Controller Core
• Manufacturer: Freescale Semiconductor, Inc

Freescale Semiconductor
Case I: If A0 < $8000 (1/2), then round down (add nothing)
Before Rounding
35
Case II: If A0 > $8000 (1/2), then round up (add 1 to A1)
Before Rounding
35
Case III: If A0 = $8000 (1/2), and the LSB of A1 = 0 (even), then round down (add nothing)
Before Rounding
35
Case IV: If A0 = $8000 (1/2), and the LSB = 1 (odd), then round up (add 1 to A1)
Before Rounding
35
*A0 is always clear; performed during RND, MPYR, MACR
X X . . X X X X X . . . X X X 0 1 0 0 0 1 1 X X X . . . . X X X
X X . . X X X X X . . . X X X 0 1 0 0 1 1 1 0 X X . . . . X X X
X X . . X X X X X . . . X X X 0 1 0 0 1 0 0 0 . . . . . . . . 0 0 0
X X . . X X X X X . . . X X X 0 1 0 1 1 0 0 0 . . . . . . . . 0 0 0
A2
A2
A2
A2
32 31
32 31
32 31
32 31
A1
A1
A1
A1
16 15
16 15
16 15
16 15
0
0
1
1
Figure 5-28. Convergent Rounding
A0
A0
A0
A0
Data Arithmetic Logic Unit
0
0
0
0
After Rounding
35
After Rounding
35
After Rounding
35
After Rounding
35
X X . . X X X X X . . . X X X 0 1 0 0 0 0 0 . . . . . . . . . 0 0 0
X X . . X X X X X . . . X X X 0 1 0 1 0 0 0 . . . . . . . . . 0 0 0
X X . . X X X X X . . . X X X 0 1 0 0 0 0 0 . . . . . . . . . 0 0 0
X X . . X X X X X . . . X X X 0 1 1 0 0 0 0 . . . . . . . . . 0 0 0
A2
A2
A2
A2
32 31
32 31
32 31
32 31
A1
A1
A1
A1
16 15
16 15
16 15
16 15
A0*
A0*
A0*
A0*
Rounding
5-45
0
0
0
0