h8s-2649 Renesas Electronics Corporation., h8s-2649 Datasheet - Page 106

• Manufacturer Part Number: h8s-2649
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

Section 4 Exception Handling
4.8
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:
Use the following instructions to restore registers:
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.
Rev. 2.00 Dec. 05, 2005 Page 68 of 724
REJ09B0200-0200
SP
Note: This diagram illustrates an example in which the interrupt control mode is 0, in advanced mode.
PUSH.W
PUSH.L
POP.W
POP.L
[Legend]
CCR :
PC :
R1L :
SP :
SP set to H'FFFEFF
Usage Note
Condition code register
Program counter
General register R1L
Stack pointer
Rn
Rn
ERn
ERn
Figure 4.4 Operation when SP Value Is Odd
(or MOV.W Rn, @-SP)
(or MOV.W @SP+, Rn)
(or MOV.L ERn, @-SP)
(or MOV.L @SP+, ERn)
SP
TRAP instruction executed
Data saved above SP
CCR
PC
SP
MOV.B R1L, @-ER7 instruction executed
Contents of CCR lost
R1L
PC
H'FFFEFA
H'FFFEFB
H'FFFEFC
H'FFFEFD
H'FFFEFE
H'FFFEFF
Address