XC2200 Derivatives
System Units (Vol. 1 of 2)
Central Processing Unit (CPU)
User’s Manual
4-64
V2.1, 2008-08
CPUSV2_X, V2.2
4.9
DSP Data Processing (MAC Unit)
The new CoXXX arithmetic instructions are performed in the MAC unit. The MAC unit
provides single-instruction-cycle, non-pipelined, 32-bit additions; 32-bit subtraction; right
and left shifts; 16-bit by 16-bit multiplication; and multiplication with cumulative
subtraction/addition. The MAC unit includes the following major components, shown in
•
16-bit by 16-bit signed/unsigned multiplier with signed result
1)
•
Concatenation Unit
•
Scaler (one-bit left shifter) for fractional computing
•
40-bit Adder/Subtracter
•
40-bit Signed Accumulator
•
Data Limiter
•
Accumulator Shifter
•
Repeat Counter
Figure 4-18 Functional MAC Unit Block Diagram
1) The same hardware-multiplier is used in the ALU.
MCA04930
40-Bit Adder/Subtracter
Signed
Ext.
Round + Saturation
32
Signed/
Unsigned
Multiplier
Concatenation
Unit
32
32
16
16
16
16
16-Bit Input Operands
40
40-Bit Signed
Accumulator
Limiter
40
ACCU-Shifter
40
40
MSW Register
Repeat Counter
MCW Register