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

4.8

Usage Note

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 what
happens 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)
CCR
SP
PC
TRAP instruction executed
Data saved above SP

Figure 4.4 Operation when SP Value is Odd

Section 4 Exception Handling
R1L
SP
PC
MOV.B R1L, @-ER7 executed
Contents of CCR lost
Rev. 6.00 Mar 15, 2006 page 65 of 570
REJ09B0211-0600
Address
H'FFFEFA
H'FFFEFB
H'FFFEFC
H'FFFEFD
H'FFFEFE
H'FFFEFF