r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 134

• Manufacturer Part Number: r4f2456
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

Section 4 Exception Handling
4.9
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 operation
when the SP value is odd.
Rev. 1.00 Sep. 19, 2008 Page 104 of 1342
REJ09B0467-0100
SP
PUSH.W
PUSH.L
POP.W
POP.L
Note: This diagram illustrates an example in which the interrupt control mode is 0, in advanced mode.
Usage Note
Legend:
CCR :
R1L :
PC :
SP :
SP set to H'FFFEFF
Condition code register
Program counter
General register R1L
Stack pointer
Rn
ERn
Rn
ERn
TRAP instruction executed
Figure 4.4 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'FFFEFE
H'FFFEFF
Address