HD6432633 Datasheet, PDF (174/1453 Pages) Renesas Technology Corp – Series of Microcomputers (MCUs: microcomputer units)

4.7 Notes on Use of the Stack
When accessing word data or longword data, the H8S/2633 Series assumes that the lowest address
bit is 0. The stack should always be accessed by word transfer instruction or longword transfer
instruction, and the value of the stack pointer (SP, ER7) should always be kept even. Use the
following instructions to save registers:
PUSH.W Rn (or MOV.W Rn, @-SP)
PUSH.L ERn (or MOV.L ERn, @-SP)
Use the following instructions to restore registers:
POP.W
POP.L
Rn (or MOV.W @SP+, Rn)
ERn (or MOV.L @SP+, ERn)
Setting SP to an odd value may lead to a malfunction. Figure 4-6 shows an example of what
happens when the SP value is odd.
CCR
SP
R1L
H'FFFEFA
SP
H'FFFEFB
PC
PC
H'FFFEFC
H'FFFEFD
SP
H'FFFEFF
TRAP instruction executed MOV.B R1L, @–ER7
SP set to H'FFFEFF Data saved above SP Contents of CCR lost
Legend CCR: Condition code register
PC: Program counter
R1L: General register R1L
SP: Stack pointer
Note: This diagram illustrates an example in which the interrupt control mode
is 0, in advanced mode.
Figure 4-6 Operation when SP Value is Odd
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