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From: ld AT jasmine DOT netrix DOT com (Long Doan)
Subject: Re: [Q] ISR - Stack switching
Lines: 51
Sender: root AT netrix DOT com
Organization: Netrix Corporation
References: <813408666 DOT 180snx AT techm DOT pl DOT my>
Date: Fri, 13 Oct 1995 14:51:26 GMT
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Dj-Gateway: from newsgroup comp.os.msdos.djgpp

In article <813408666 DOT 180snx AT techm DOT pl DOT my> kenfoo AT techm DOT pl DOT my (Kenneth Foo) writes:

> Question.
> How do we switch stacks in an interrupt service routine?

Some sample of code:
    asm ("
/*--------------------------------------------------------------------
    Switch stack.
--------------------------------------------------------------------*/
    pushl %eax
    pushl %ebx
    movl  %esp, %eax
    movw  %ss,  %bx
    pushl %ds
    popl  %ss
    movl  _My_isr_stack_end, %esp
    pushl $0
    pushl %eax
    pushl %ebx

/*--------------------------------------------------------------------
    Do whatever is necessary here
--------------------------------------------------------------------*/
    call  _my_big_interrupt_service_routine

/*--------------------------------------------------------------------
    Switch stack back.
--------------------------------------------------------------------*/
    popl  %ebx
    popl  %eax
    movw  %bx, %ss
    movl  %eax, %esp
    popl  %ebx
    popl  %eax
    ");

> Must %esp be doubleword (4-byte) aligned?

Yep.

Hope that helps,
Long.

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Long Doan                                        ld AT netrix DOT com     
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