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[avr-gcc-list] Writing ASM libraries for avr-gcc
From: |
Larry Barello |
Subject: |
[avr-gcc-list] Writing ASM libraries for avr-gcc |
Date: |
Tue, 10 Sep 2002 11:44:43 -0700 |
Sometime ago there was a file "ctoasm.inc" which detailed the parameter
passing sequence and the registers one could clobber in their assembly
routine. I cannot find it anywhere (well I found an old pre 2.97 one) and
wanted to verify that R30:31 are clobberable registers in the subroutine.
Currently this is my understanding:
R24:25 - P1
R22:23 - P2 Byte, Word, Long
R20:21 - P3 etc
R18:19 - P4 etc
All the above registers along with R0 and R1 (with restoring to 0) R26, 27,
30 and 31 are freely clobberable. R1-R17 and (maybe) R27:28 need to be
preserved.
Thanks!
avr-gcc-list at http://avr1.org
- [avr-gcc-list] Writing ASM libraries for avr-gcc,
Larry Barello <=