flat assembler
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Spool



Joined: 08 Jan 2013
Posts: 154
Spool
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Last edited by Spool on 17 Mar 2013, 04:04; edited 2 times in total
Post 10 Jan 2013, 14:44
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shutdownall



Joined: 02 Apr 2010
Posts: 518
Location: Munich
shutdownall
It's not efficient to work with 8 bit data and 64 bit addresses.
How would you calculate and how many operations do you want to combine to realize a 64 bit addition or subtraction ? And what about multiplication or division ?

I don't know any 8 bit processor supporting 64 bit address range. It's not handy nor is it necessary. You write yourself you could spare hard disk and memory with 8 bit calculating. So if you spare it, for what do you need 64 bit addresses ?

With 32 bit you can address 4 GB memory. For what the hell do you need about 4 billion pages (!) of 4 GB ?

So I don't understand your approach. There is version of flatassembler for Zilog's 8-bit Z80 CPU. You can try work with that but offers only 16 bit address range / 64 kByte.

Or you explain a bit more detailed what you want to do.
Post 10 Jan 2013, 17:44
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cod3b453



Joined: 25 Aug 2004
Posts: 619
cod3b453
There's nothing stopping you from storing 8bit offsets from a 64bit base address and combining them to form the actual address:
Code:
use64

mov rax,0x100000000     ; 64bit base address +0x80 for SX
mov bl,0x80             ; 8bit offset

movzx edx,bl            ; or movsx for sign extended
lea rsi,[rax+rdx]       ; final address    
but I'm not sure if this is what you mean Question
Post 10 Jan 2013, 19:46
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Spool



Joined: 08 Jan 2013
Posts: 154
Spool
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Last edited by Spool on 17 Mar 2013, 04:45; edited 1 time in total
Post 27 Jan 2013, 03:51
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cod3b453



Joined: 25 Aug 2004
Posts: 619
cod3b453
Assuming you only address 64bit values, simply adjust the offset:
Code:
...
lea rsi,[rax+8*rdx]       ; final address    
Question
Post 27 Jan 2013, 13:32
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