HD6432147SW datasheet(156/1177 Pages) RENESAS

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Section 4 Exception Handling

Rev. 4.00 Sep 27, 2006 page 112 of 1130

REJ09B0327-0400

4.6

Notes on Use of the Stack

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

(or MOV.W Rn, @-SP)

PUSH.L

ERn

(or MOV.L ERn, @-SP)

Use the following instructions to restore registers:

POP.W

(or MOV.W @SP+, Rn)

POP.L

ERn

(or MOV.L @SP+, ERn)

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.

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.

CCR

R1L

H'FFEFFA

H'FFEFFB

H'FFEFFC

H'FFEFFD

H'FFEFFF

MOV.B R1L, @–ER7

SP set to H'FFEFFF

TRAP instruction executed

Data saved above SP

Contents of CCR lost

Figure 4.6 Operation when SP Value Is Odd

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