Micro-programmed State Machines - Digital Design of Signal Processing Systems: A Practical Approach - page 440

Loop_Count
fields from micro-
code

end_addr fields

From
PC

from
Microcode

Start Address
Stack

Loop Count
Stack

End Address
Stack

N

N L

0
1
2
3

write_en

current

current current

2 2 2

N N L

loop instr

P N

To Next Address
Generation Unit

rst_n

Down Counter

clk

comparator

2
2

Stack Pointer logic

dec

incremented

L
NOR

clk

Zero
Check
Logic

Push SP OR
Loop End Flag

1

rst_n

1

1

1

To Next Address
Generation Unit

loop count not 0

Figure 10.20 Loop machine with four-nested-loop support