Usage Notes; Figure 4.4 Operation When Sp Value Is Odd - Renesas H8S/2368 Series Hardware Manual

4.8

Usage Notes

When accessing word data or longword data, this LSI 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
PUSH.L ERn
Use the following instructions to restore registers:
POP.W Rn
POP.L ERn
Setting SP to an odd value may lead to a malfunction. Figure 4.4 shows an example of operation
when the SP value is odd.
SP
SP set to H'FFFEFF
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.
(or MOV.W Rn, @-SP)
(or MOV.L ERn, @-SP)
(or MOV.W @SP+, Rn)
(or MOV.L @SP+, ERn)
SP
TRAP instruction executed
Data saved above SP

Figure 4.4 Operation when SP Value Is Odd

CCR
SP
PC
MOV.B R1L, @-ER7
Contents of CCR lost
Rev. 2.00, 05/03, page 77 of 820
Address
H'FFFEFA
R1L
H'FFFEFB
PC
H'FFFEFC
H'FFFEFD
H'FFFEFE
H'FFFEFF