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Section 3 Exception Handling
Rev. 6.00 Sep 12, 2006 page 78 of 526
REJ09B0326-0600
3.4 Application
Notes
3.4.1
Notes on Stack Area Use
When word data is accessed in the H8/3644 Group, the least significant bit of the address is
regarded as 0. Access to the stack always takes place in word size, so the stack pointer (SP: R7)
should never indicate an odd address. Use PUSH Rn (MOV.W Rn, @–SP) or POP Rn (MOV.W
@SP+, Rn) to save or restore register values.
Setting an odd address in SP may cause a program to crash. An example is shown in figure 3.6.
PC
PC
R1L
PC
SP
SP
SP
H'FEFC
H'FEFD
H'FEFF
→
→
→
H
L
L
MOV. B R1L, @–R7
SP set to H'FEFF
Stack accessed beyond SP
BSR instruction
Contents of PC are lost
H
Legend:
PC
H
:
PC
L
:
R1L:
SP:
Upper byte of program counter
Lower byte of program counter
General register R1L
Stack pointer
Figure 3.6 Operation when Odd Address Is Set in SP
When CCR contents are saved to the stack during interrupt exception handling or restored when
RTE is executed, this also takes place in word size. Both the upper and lower bytes of word data
are saved to the stack; on return, the even address contents are restored to CCR while the odd
address contents are ignored.
Содержание F-ZTAT H8/3642A Series
Страница 6: ...Rev 6 00 Sep 12 2006 page iv of xx ...
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Страница 21: ...Rev 6 00 Sep 12 2006 page xix of xx Appendix E Product Code Lineup 522 Appendix F Package Dimensions 524 ...
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Страница 124: ...Section 5 Power Down Modes Rev 6 00 Sep 12 2006 page 102 of 526 REJ09B0326 0600 ...
Страница 188: ...Section 6 ROM Rev 6 00 Sep 12 2006 page 166 of 526 REJ09B0326 0600 ...
Страница 190: ...Section 7 RAM Rev 6 00 Sep 12 2006 page 168 of 526 REJ09B0326 0600 ...
Страница 298: ...Section 9 Timers Rev 6 00 Sep 12 2006 page 276 of 526 REJ09B0326 0600 ...
Страница 378: ...Section 12 A D Converter Rev 6 00 Sep 12 2006 page 356 of 526 REJ09B0326 0600 ...
Страница 446: ...Section 13 Electrical Characteristics Rev 6 00 Sep 12 2006 page 424 of 526 REJ09B0326 0600 ...