Hardware Processing For Accepting And Returning From Exceptions - Renesas RX100 Series User Manual

RX13T Group
13.4

Hardware Processing for Accepting and Returning from Exceptions

This section describes the hardware processing for accepting and returning from exceptions other than a reset.
(1) Hardware Pre-Processing for Accepting an Exception
(a) Saving PSW
 For a fast interrupt
PSW → BPSW
 For exceptions other than a fast interrupt
PSW → Stack
Note: The values in FPSW are not saved by hardware pre-processing. Therefore, if floating-point instructions are to be
used within an exception handling routine, the user must save these values on the stack within the exception
handling routine.
(b) Updating PM, U, and I Bits in PSW
I: Set to 0
U: Set to 0
PM: Set to 0
(c) Saving PC
 For a fast interrupt
PC → BPC
 For exceptions other than a fast interrupt
PC → Stack
(d) Setting Branch Destination Address of Exception Handling Routine in PC
Processing is shifted to the exception handling routine by acquiring the vector corresponding to the exception and then
branching accordingly.
(2) Hardware Post-Processing for Execution of RTE and RTFI Instructions
(a) Restoring PSW
 For a fast interrupt
BPSW → PSW
 For exceptions other than a fast interrupt
Stack → PSW
(b) Restoring PC
 For a fast interrupt
BPC → PC
 For exceptions other than a fast interrupt
Stack → PC
R01UH0822EJ0100 Rev.1.00
Jul 31, 2019
13. Exception Handling
Page 194 of 1041