> -----Original Message----- > From: Andy H [mailto:hutchinsona...@aim.com] > Sent: Thursday, December 17, 2009 6:46 PM > To: Dusan Ferbas > Cc: Andrew Hutchinson; avr-gcc-list@nongnu.org; Weddington, Eric > Subject: Re: [avr-gcc-list] Why are we using EICALL and EIJMP > for AVR256? > > > It is not possible to handle EIND inside gcc (before gas and linker). > Pointer are only 16 bits
In GCC HEAD, which is future 4.5, there is a new "multiple address space feature" that was recently added and is being used in the spu port, and recently one other port. Ideally we need to: - Have the avr port use the multiple address space feature. This will also let us have the ability to have pointers to flash, pointers to ram, pointers to eeprom, and read data out of flash into ram and have gcc generate the lpm instructions for this. - With multiple address spaces, we can have multiple pointer sizes. We need to set the pointer size according to the memory size so that the atmega256x devices will have (nominally) 24-bit pointers, but smaller flash sizes (such as atmega128) have a 16-bit pointer. With 24-bit pointer sizes, we can get rid of the 'trampolines' that cause so many problems and confusion. The trampoline idea, when it was implemented, was a compromise anyway and it was known that it was a bit of a kludge. Granted this may be a lot of work, but this is the direction that the avr port must go in. Eric _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
