[avr-gcc-list] How to do multi-line assembler macros?

[Brian Dean]

Hi,

I'm writing some assembler routines where the use of C #define macros
would make my life a lot easier.  I need to write a macro of the form:

        lds     r0, servo_0
        tst     r0
        brne    servos_reset_0_over_1
        cbi     SERVO_0_PORT, SERVO_0_BIT
        rjmp    servos_reset_0_over
servos_reset_0_over_1:
        sbi     SERVO_0_PORT, SERVO_0_BIT

There are lots of servos, so I'd like to write a macro like this:

#define RESET_SERVO(servo) \
        lds     r##servo, servo_##servo ;\
        tst     r##servo ;\
        brne    servos_reset_##servo##_over_1 ;\
        cbi     SERVO_##servo##_PORT, SERVO_##servo##_BIT; \
        rjmp    servos_reset_##servo##_over; \
servos_reset_##servo##_over_1: \
        sbi     SERVO_##servo##_PORT, SERVO_##servo##_BIT; \
servos_reset_##servo##_over:

To be used like so:

        RESET_SERVO(0)
        RESET_SERVO(1)
        ...

However, the macro expands as follows:

        lds r0, servo_0 ; tst r0 ; brne servos_reset_0_over_1 ; cbi ((0x1B) + 
0), 0; rjmp servos_reset_0_over; servos_reset_0_over_1: sbi ((0x1B) + 0), 0; 
servos_reset_0_over:

Thus, due to the ';' character identifying the beginning of a comment,
only the first 'lds r0, servo_0' instruction is actually assembled.
I've tried preceding the continuation character '\' with '\n' thinking
maybe that would direct the preprocessor to generate linefeeds, but it
didn't.  Also, if I remove the ';', I get the assembler error: "Error:
garbage at end of line".

Is there a way to make this work using #define macros?

BTW, this construct works just fine using the native i386 gas
assembler.  Maybe it treats ';' as "end of instruction" instead of
"beginning of comment".  Could the assembler syntax be that different
to treat the meaning of ';' different between the two targets (AVR vs
i386)?

Does anyone know how to do this and make it work?

Any help is appreciated.

Thanks,
-Brian
-- 
Brian Dean, address@hidden
BDMICRO - Maker of the MAVRIC ATmega128 Dev Board
http://www.bdmicro.com/