HD6412240 RENESAS [Renesas Technology Corp], HD6412240 Datasheet - Page 144

• Manufacturer Part Number: HD6412240
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family / H8S/2200 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 4 Exception Handling
4.6
When accessing word data or longword data, the H8S/2245 Group 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 4.6 shows an example of what
happens when the SP value is odd.
Rev.3.00 Mar. 26, 2007 Page 102 of 772
REJ09B0355-0300
SP
PUSH.W
PUSH.L
POP.W
POP.L
Note: This diagram illustrates an example in which the interrupt control mode is 0,
Legend:
Notes on Use of the Stack
SP set to H'FFFEFF
in advanced mode.
CCR: Condition code register
PC:
R1L: General register R1L
SP:
Rn
ERn
Rn
ERn
TRAPA instruction executed
Stack pointer
Program counter
Figure 4.6 Operation when SP Value is Odd
(or MOV.W Rn, @-SP)
(or MOV.L ERn, @-SP)
(or MOV.W @SP+, Rn)
(or MOV.L @SP+, ERn)
SP
Data saved above SP
CCR
PC
MOV.B R1L, @–ER7
SP
Contents of CCR lost
R1L
PC
H'FFFEFA
H'FFFEFB
H'FFFEFC
H'FFFEFD
H'FFFEFF