EIT
4.13 Precautions on EIT
4
4.13 Precautions on EIT
The Address Exception (AE) requires caution because if one of the instructions that use “register indirect + register
update” addressing mode (following three) generates an address exception when it is executed, the values of the
registers to be automatically updated (Rsrc and Rsrc2) become undefined.
Except that the values of Rsrc and Rsrc2 become undefined, these instructions behave the same way as when
used in other addressing modes.
• Applicable instructions
LD
ST
ST
Rdest, @Rsrc+
Rsrc1, @-Rsrc2
Rsrc1, @+Rsrc2
If the above case applies, consider the fact that the register values become undefined when you design the processing
to be performed after executing said instructions. (If an address exception occurs, it means that the system has some
fatal fault already existing in it. Therefore, address exceptions must be used on condition that control will not be returned
from the address exception handler to the program that was being executed when the exception occurred.)
32180 Group User’s Manual (Rev.1.0)
4-22
RENESAS [ RENESAS TECHNOLOGY CORP ]
