Shell Programming and Scripting

The log file reads as follows.

D function_add() ADD input data 1021214
0 VAR1 STR 10
0 VAR2 STR 20
0 VAR3 STR
1 SUM=VAR1+VAR2
D function_add() ADD output data 1021267
0 DISPLAY SUM

D function_sub() SUB input data 1021214
0 VAR1 STR 10
0 VAR2 STR 20
0 VAR3 STR
1 sub=VAR1-VAR2
D function_sub() SUB output data 1021267
0 DISPLAY sub

I want to get the output as follows in PERL script. i.e i want to get the lines inbetween "D function_add() ADD input data 1021214" and "D function_sub() SUB input data 1021214".
Kindly suggest ideas for me to write in PERL script

Sample OUTPUT
------------------------
OPCODE is ADD
Input function
0 VAR1 STR 10
0 VAR2 STR 20
0 VAR3 STR
1 SUM=VAR1+VAR2
Output function
0 DISPLAY SUM
-------------------------
-------------------------
OPCODE IS SUB
Input function
0 VAR1 STR 10
0 VAR2 STR 20
0 VAR3 STR
1 sub=VAR1-VAR2
output function
0 DISPLAY SUB
-------------------------

Code:

open LOG, "a";

$print_ind = 0;

while ( <LOG> ){

  $print_ind = 0 if ( m/D function_sub\(\) SUB input data 1021214/ );

  print if $print_ind;

  $print_ind = 1 if ( m/D function_add\(\) ADD input data 1021214/ );
  
  }

Code:

while(<DATA>){
	if(/.*?() (\S*)\s*input/){
		print "OPCODE is $1\n";
		print "Input function\n";
	}
	elsif(/output/){
		print "Output function\n";
	}
	else{
		print;
	}
}
__DATA__
D function_add() ADD input data 1021214
0 VAR1 STR 10
0 VAR2 STR 20
0 VAR3 STR
1 SUM=VAR1+VAR2
D function_add() ADD output data 1021267
0 DISPLAY SUM

D function_sub() SUB input data 1021214
0 VAR1 STR 10
0 VAR2 STR 20
0 VAR3 STR
1 sub=VAR1-VAR2
D function_sub() SUB output data 1021267
0 DISPLAY sub