HD6412320 RENESAS [Renesas Technology Corp], HD6412320 Datasheet - Page 139

• Manufacturer Part Number: HD6412320
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family H8S-2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

4.7
When accessing word data or longword data, the chip 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 4.5 shows an example of what
happens when the SP value is odd.
Legend:
CCR: Condition code register
PC:
R1L: General register R1L
SP:
Note: This diagram illustrates an example in which the interrupt control mode is 0, in advanced
PUSH.W
PUSH.L
POP.W
POP.L
Notes on Use of the Stack
SP
Stack pointer
Program counter
mode.
SP set to H'FFFEFF
Rn
ERn
Rn
ERn
TRAP instruction executed
Figure 4.5 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
Rev.6.00 Sep. 27, 2007 Page 109 of 1268
SP
Contents of CCR lost
Section 4 Exception Handling
R1L
PC
H'FFFEFA
H'FFFEFB
H'FFFEFC
H'FFFEFD
REJ09B0220-0600