Fig. 5.3.3 Correction Example (2) - Renesas 7200 Series User Manual

APPLICATION
5.3 Usage example of ROM correction function (M37221M8/MA-XXXSP)
(2) Correction example 2
The loop processing is performed between
shown in detail. Example A corrects in loop units and example B corrects only error instructions.
Examples A and B are the same operation, differing in processing time and correction bytes only.
Depending on the contents of loop processing, it may be preferable to include correct codes with the
codes to be corrected, simplifying the correction program and making it easier to read.
When omitting FE96H ( ) and correcting from FE98H, the program cannot move to FE96H by the
BPL instruction (the jump destination addresses of the BPL instruction are limited to bytes between
–128 and +127). Therefore, the example B is provided.
Program before correction
Address
Machine
instructions
FE96 9525
FE98 CA
FE99 10FB
FE9B 60
Notes 1: In , FE9BH is specified as the return destination address of JMP.
In this example, since the instruction at the return destination address is
RTS is used instead of JMP , the operation is the same as that of JMP .
even if
As a result, the number of bytes is reduced.
2: BPL and BMI, as machine instructions, have no absolute addresses, but relative
addresses as branch destinations.

Fig. 5.3.3 Correction example (2)

5-16
Description style
025H, X
STA
DEX
BPL 0FE96H
(See note 2)
RTS
7220 Group User's Manual
and in Figure 5.3.3. Two examples of this part are
Example A
Correction program
Address Machine
(block 2) instructions
02E0 9525
02E2 9D2501
02E5 3A
02E6 CA
02E7 10F7
02E9 60
Example B
Correction program
Address Machine
(block 2) instructions
02E0 9D2501
02E3 3A
02E4 CA
02E5 3003
02E7 4C96FE
4C9BFE
02EA
RTS,
Description style
025H, X
STA
STA 0125H, X
INC A
DEX
BPL
02E0H
(See note 2)
RTS (See note 1)
Description style
STA 0125H, X
INC A
DEX
BMI
02EAH
(See note 2)
JMP FE96H
JMP
FE9BH
(See note 1)