SH7059 Datasheet, PDF (166/1042 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

6. Exception Processing
6.8.3 Address Errors Caused by Stacking of Address Error Exception Processing
When the stack pointer is not a multiple of four, an address error will occur during stacking of the exception processing
(interrupts, etc.) and address error exception processing will start up as soon as the first exception processing is ended.
Address errors will then also occur in the stacking for this address error exception processing. To ensure that address error
exception processing does not go into an endless loop, no address errors are accepted at that point. This allows program
control to be shifted to the address error exception service routine and enables error processing.
When an address error occurs during exception processing stacking, the stacking bus cycle (write) is executed. During
stacking of the status register (SR) and program counter (PC), the SP is decremented by 4 for both, so the value of SP will
not be a multiple of four after the stacking either. The address value output during stacking is the SP value, so the address
where the error occurred is itself output. This means the write data stacked will be undefined.
Rev.3.00 Mar. 12, 2008 Page 76 of 948
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