HD64F2145 datasheet(124/829 Pages) RENESAS

124 / 829 page

Rev. 2.0, 08/02, page 84 of 788

4.7

Usage Note

When accessing word data or longword data, this LSI assumes that the lowest address bit is 0. The

stack should always be accessed in words or longwords, 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 4.3 shows an example of what

happens when the SP value is odd.

CCR :

PC :

R1L :

SP :

Condition code register

Program counter

General register R1L

Stack pointer

CCR

R1L

H'FFEFFA

H'FFEFFB

H'FFEFFC

H'FFEFFD

H'FFEFFF

TRAPA instruction executed

SP set to H'FFFEFF

Data saved above SP

MOV.B R1L, @-ER7 executed

Contents of CCR lost

Address

Legend

Note: This diagram illustrates an example in which the interrupt control mode is 0 in advanced mode.

Figure 4.3 Operation when SP Value is Odd

HD64F2145 Datasheet(PDF) 124 Page - Renesas Technology Corp

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