A proposal has been made at the discussion group that the BBC BASIC assembler be adapted for 64-bit addressing as follows:
The 'program counter', which is P% in all previous versions, will become P% (low 32-bits) + Q% (high 32-bits).
The 'code limit', which is L% in all previous versions, will become L% (low 32-bits) + M% (high 32-bits).
(The 'code origin', O%, is virtually never used so is not considered here; see the group for more details).
The implication of this proposal is that allocation of memory for the assembler would need to be done like this, or similar:
Code: DIM limit -1, mcode size%, limit -1 FOR pass% = 8 TO 10 STEP 2 P% = !^mcode : Q% = mcode>>32 L% = !^limit : M% = limit>>32 [OPT pass% .... ] NEXT pass%
An alternative approach, using the 64-bit indirection operator in the 64-bit versions of BBC BASIC, would be as follows:
Code: DIM limit -1, mcode size%, limit -1 FOR pass% = 8 TO 10 STEP 2 ]^P% = mcode ]^L% = limit [OPT pass% .... ] NEXT pass%
If anybody has any comments on, or objections to, these proposals speak now or forever hold your peace!
Note that there is currently no 64-bit assembler to take advantage of these changes; I am relying on both the x86-64 and aarch64 assemblers being contributed by users, and to date nobody has offered to do so.
Richard.
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