> ----- Message from Georg-Johann Lay <a...@gjlay.de> on Thu, 22 Jan > 2009 00:06:15 +0100 ----- > > To: > > Colin Wall <col...@pec.co.nz> > > cc: > > avr-gcc-list@nongnu.org > > Subject: > > Re: [avr-gcc-list] Using __tmp_reg__ etc in assembly file > > Colin Wall schrieb: > > Hi List, > > > > I must be missing something. > > > > I can use symbols like __SREG__, __tmp_reg__ and __zero_reg__ in in-line > > asm (e.g. "push __tmp_reg__") but if I do the same in a pure assembly > > file, the compiler complains with "constant value required". How does one > > access these symbols in the assembly file and keep gas happy? > > gcc gererates a header in easch assembly output that looks like > > .file "fifo.c" > .arch atmega168 > __SREG__ = 0x3f > __SP_H__ = 0x3e > __SP_L__ = 0x3d > __tmp_reg__ = 0 > __zero_reg__ = 1 > .global __do_copy_data > .global __do_clear_bss > ; GNU C version 3.4.6 (avr) > > Newer versions ov gcc even define more. So the __tmp_reg__ is not a > symbol it's just a definiton. So > > push __tmp_reg__ > > is equivalent to > > push 0 > > and yes, there is no (redundant) register prefix "R" in this case. > > > > I know I can always do my own #define, but it feels wrong to re-define
> > something that already exists... > > No, it does not exist in any header. It exists in gcc ;-) > > Georg-Johann > So, from what I can see, the compiler makes these defines available to C source, but not to asm (.S) source, and I need to repeat them myself in the asm file to use them there. Thanks for your help Georg-Johann. Colin. > > > > > ----- Message from Ruud Vlaming <r...@betaresearch.nl> on Thu, 22 > Jan 2009 00:28:57 +0100 ----- > > To: > > avr-gcc-list@nongnu.org > > Subject: > > Re: [avr-gcc-list] Using __tmp_reg__ etc in assembly file > > On Wednesday 21 January 2009 23:09, Colin Wall wrote: > > > I know I can always do my own #define, but it feels wrong to re-define > > something that already exists... > > You can make use of the constructions (examples): > out (_SFR_IO_ADDR(SREG)), r25 > out (_SFR_IO_ADDR(SPL)), r26 > out (_SFR_IO_ADDR(SPH)), r27 > etc, if i remember correctly. > > Ruud. > > These work in the asm file because SREG etc are defined when io.h is included. I can't see a way to use __tmp_reg__ et al without re-defining them myself. Colin. ########################################################################### This e-mail is confidential and may contain information subject to legal privilege. If you are not the intended recipient please advise us of our error by return e-mail then delete this e-mail and any attached files. You may not copy, disclose or use the contents in any way. The views expressed in this e-mail may not be those of Gallagher Group Ltd or subsidiary companies thereof. ########################################################################### _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
