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Re: [avr-libc-dev] Re: C++ Interrupts

From: Joerg Wunsch
Subject: Re: [avr-libc-dev] Re: C++ Interrupts
Date: Sun, 20 Jan 2008 20:29:27 +0100
User-agent: Mutt/1.5.11

As Dean Camera wrote:

> My solution:
>         #define CLASS_ISR(vector, ...) { vector(); } ISR(vector, __VA_ARGS__)


> Which means you can name the function anything, and it should be
> accessible as a normal function, but also link in as an ISR. As I
> can't seem to get the intermixed assembly listing, I can't see how
> effective it is, but it should allow you to call the ISR by the
> member function name you give it, with either no penalty at all (if
> the optimizer inlines it) or a small penalty of a JUMP instruction.

The only downside appears to be one empty instance of

0000010a <__bad_interrupt>:
 10a:   0c 94 00 00     jmp     0       ; 0x0 <__heap_end>

0000010e <Test::~Test()>:
 10e:   08 95           ret

00000110 <Test::~Test()>:
 110:   08 95           ret

00000112 <Test::__vector_29()>:
 112:   08 95           ret

00000114 <Test::Test()>:
 114:   08 95           ret

00000116 <Test::Test()>:
 116:   08 95           ret

00000118 <__vector_29>:
 118:   f 92            push    r1
 11a:   0f 92           push    r0
 11c:   0f b6           in      r0, 0x3f        ; 63
 11e:   0f 92           push    r0
 120:   11 24           eor     r1, r1
 122:   8f 93           push    r24
 124:   8f ef           ldi     r24, 0xFF       ; 255
 126:   88 b9           out     0x08, r24       ; 8
 128:   8f 91           pop     r24
 12a:   0f 90           pop     r0
 12c:   0f be           out     0x3f, r0        ; 63
 12e:   0f 90           pop     r0
 130:   f 90            pop     r1
 132:   18 95           reti

00000134 <main>:

Btw., I remember that Marek once mentioned an idea how the entire
interrupt vector setup could be changed so arbitrarily named interrupt
vectors are possible.  However, I cannot find his idea at a quick
glance in my archive of avr-libc-dev, so I guess it has been discussed
in avr-gcc-list by its time (which I do not archive personally).  I
just remembered that idea when Ron asked that question in
avrfreaks.net because I think it will also provide a solution.

Anyway, the macro above looks as a really good start to me, and even
when/if we've got a different vector naming scheme some day, it would
be as simple to adapt that macro to the new scheme, so the API will be

cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)

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