Re: [avr-gcc-list] gcc prolog incorrect?

[HutchinsonAndy]

So what happens if we get interrupt between 69 and 70? And that interrupt 
disables interrupts?



HutchinsonAndy wrote:

>As you describe is exactly what I am concerned about!
>
>
>"Ben L. Titzer" <address@hidden> wrote:
>
>>It seems as though the code restores the interrupt mask to exactly as 
>>it was before the call; if the cli were to come first, the I flag would 
>>be written to 0 and thus would not be restored correctly.
>>
>>The thing I wonder about is what happens if there is an interrupt 
>>between 72 and 73....It seems to me that those two instructions should 
>>be swapped...
>>
>>On Mar 6, 2005, at 6:12 PM, address@hidden wrote:
>>
>>> Is it possible that gcc prolog is incorrect?
>>>
>>>   69 000a 0FB6              in __tmp_reg__,__SREG__
>>>   70 000c F894              cli
>>>   71 000e DEBF              out __SP_H__,r29
>>>   72 0010 0FBE              out __SREG__,__tmp_reg__
>>>   73 0012 CDBF              out __SP_L__,r28
>>>
>>> This is the code used to adjust the stack pointer for a regular 
>>> function with interrupts active. Basically it turns of interupts so it 
>>> can chnage both bytes of SP without a problem.
>>>
>>> But saved BEFORE interrupts are disabled. Doesn't that mean that if 
>>> interrupts were disabled during ISR, a function could re-enabled them 
>>> when SREG is restored?
>>>
>>>
>>>
>>> -- 
>>> Andy Hutchinson
>>>
>>>
>>> __________________________________________________________________
>>> Switch to Netscape Internet Service.
>>> As low as $9.95 a month -- Sign up today at 
>>> http://isp.netscape.com/register
>>>
>>> Netscape. Just the Net You Need.
>>>
>>> New! Netscape Toolbar for Internet Explorer
>>> Search from anywhere on the Web and block those annoying pop-ups.
>>> Download now at http://channels.netscape.com/ns/search/install.jsp
>>>
>>>
>>> _______________________________________________
>>> AVR-GCC-list mailing list
>>> address@hidden
>>> http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
>>>
>>>
>>======================================================
>>Imagination is more important than knowledge.
>>-- Albert Einstein
>>
>>
>
>
>-- 
>Andy Hutchinson
>
>
>__________________________________________________________________
>Switch to Netscape Internet Service.
>As low as $9.95 a month -- Sign up today at http://isp.netscape.com/register
>
>Netscape. Just the Net You Need.
>
>New! Netscape Toolbar for Internet Explorer
>Search from anywhere on the Web and block those annoying pop-ups.
>Download now at http://channels.netscape.com/ns/search/install.jsp
>


-- 
Andy Hutchinson


__________________________________________________________________
Switch to Netscape Internet Service.
As low as $9.95 a month -- Sign up today at http://isp.netscape.com/register

Netscape. Just the Net You Need.

New! Netscape Toolbar for Internet Explorer
Search from anywhere on the Web and block those annoying pop-ups.
Download now at http://channels.netscape.com/ns/search/install.jsp