Section 5 Exception Handling
Rev. 3.00 Sep. 27, 2007 Page 86 of 758
REJ09B0243-0300
5.8 Usage
Notes
5.8.1
Value of Stack Pointer (SP)
The SP value must always be a multiple of 4. If it is not, an address error will occur when the
stack is accessed during exception handling.
5.8.2
Value of Vector Base Register (VBR)
The VBR value must always be a multiple of 4. If it is not, an address error will occur when the
stack is accessed during exception handling.
5.8.3
Address Errors Caused by Stacking for Address Error Exception Handling
When the SP value is not a multiple of 4, an address error will occur when stacking for exception
handling (interrupts, etc.) and address error exception handling will start after the first exception
handling is ended. Address errors will also occur in the stacking for this address error exception
handling. To ensure that address error exception handling does not go into an endless loop, no
address errors are accepted at that point. This allows program control to be passed to the handling
routine for address error exception and enables error processing.
When an address error occurs during exception handling stacking, the stacking bus cycle (write) is
executed. When stacking the SR and PC values, the SP values for both are subtracted by 4,
therefore, the SP value is still not a multiple of 4 after the stacking. The address value output
during stacking is the SP value whose lower two bits are cleared to 0. So the write data stacked is
undefined.
Summary of Contents for SH7124 R5F7124
Page 2: ...Rev 3 00 Sep 27 2007 Page ii of xx ...
Page 8: ...Rev 3 00 Sep 27 2007 Page viii of xx ...
Page 36: ...Section 1 Overview Rev 3 00 Sep 27 2007 Page 16 of 758 REJ09B0243 0300 ...
Page 68: ...Section 2 CPU Rev 3 00 Sep 27 2007 Page 48 of 758 REJ09B0243 0300 ...
Page 108: ...Section 5 Exception Handling Rev 3 00 Sep 27 2007 Page 88 of 758 REJ09B0243 0300 ...
Page 166: ...Section 7 User Break Controller UBC Rev 3 00 Sep 27 2007 Page 146 of 758 REJ09B0243 0300 ...
Page 724: ...Section 20 List of Registers Rev 3 00 Sep 27 2007 Page 704 of 758 REJ09B0243 0300 ...
Page 772: ...Rev 3 00 Sep 27 2007 Page 752 of 758 REJ09B0243 0300 ...
Page 778: ...Rev 3 00 Sep 27 2007 Page 758 of 758 REJ09B0243 0300 ...
Page 781: ......