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Index > Compiler Internals > ror in FASM?

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Azu



Joined: 16 Dec 2008
Posts: 1159
Azu
"db 1234 shr 8" works.

"db 1234 ror 8" says "error: extra characters on line.".

Please help.. I can't figure out which characters are the extra ones.. Confused

I think it's some kind of weird bug.
Post 03 Mar 2009, 00:04
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Quote:

I think it's some kind of weird bug.

But it is not, fasm doesn't support such operation on expressions, it is only allowed as a CPU instruction.
Post 03 Mar 2009, 00:08
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Azu



Joined: 16 Dec 2008
Posts: 1159
Azu
LocoDelAssembly wrote:
Quote:

I think it's some kind of weird bug.

But it is not, fasm doesn't support such operation on expressions, it is only allowed as a CPU instruction.
It does with shr, though.

So is it a bug that it works for shr.. or is it a bug that it doesn't work for ror?

Either way is bug.
Post 03 Mar 2009, 00:10
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
The shr and shl, apart of being CPU instructions are also operations allowed on expressions.

TFM brilliantly says wrote:
1.2.4 Numerical expressions


In the above examples all the numerical expressions were the simple numbers,
constants or labels. But they can be more complex, by using the arithmetical
or logical operators for calculations at compile time. All these operators
with their priority values are listed in table 1.4.
The operations with higher priority value will be calculated first, you can
of course change this behavior by putting some parts of expression into
parenthesis. The +, -, * and / are standard arithmetical operations,
mod calculates the remainder from division. The and, or, xor, shl,
shr and not perform the same logical operations as assembly instructions
of those names. The rva performs the conversion of an address into the
relocatable offset and is specific to some of the output formats (see 2.4).

http://flatassembler.net/docs.php?article=manual#1.2.4
Post 03 Mar 2009, 00:38
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Azu



Joined: 16 Dec 2008
Posts: 1159
Azu
LocoDelAssembly wrote:
The shr and shl, apart of being CPU instructions are also operations allowed on expressions.

TFM brilliantly says wrote:
1.2.4 Numerical expressions


In the above examples all the numerical expressions were the simple numbers,
constants or labels. But they can be more complex, by using the arithmetical
or logical operators for calculations at compile time. All these operators
with their priority values are listed in table 1.4.
The operations with higher priority value will be calculated first, you can
of course change this behavior by putting some parts of expression into
parenthesis. The +, -, * and / are standard arithmetical operations,
mod calculates the remainder from division. The and, or, xor, shl,
shr and not perform the same logical operations as assembly instructions
of those names. The rva performs the conversion of an address into the
relocatable offset and is specific to some of the output formats (see 2.4).

http://flatassembler.net/docs.php?article=manual#1.2.4


Thanks.

Can you please tell me where shl and shr are handled (like what file and line number? I can't find them)? I will just add ror/rol support myself. It shouldn't take more then a simple copy/paste and then replacing sh with ro.




Edit: nevermind found it myself. Was easier then I thought.
Post 03 Mar 2009, 00:52
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
I'm not an expert on the matter but I'll try to give you some pointers.

First, you will probably have to add the new ops in TABLES.INC below "operators:". Then change on PARSER.INC the proc get_operator. Finally do the appropriate changes on calculate_expression at EXPRESSI.INC.

However, note that ROR and ROL can be build as a series of SHR/SHL, AND and OR, so before going so far consider if it really worth it considering you can replicate functionality with existing features.
Post 03 Mar 2009, 01:14
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17658
Location: In your JS exploiting you and your system
revolution
Post 03 Mar 2009, 02:40
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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
BUMP (4 years later)

Would it be possible to add ROL and ROR into FASM? I miss them.

(10 years old patches are no longer that useful)

Code:
mov ax, $CD SHL 3
; mov ax, $CD ROL 3 ; !!! BUGGED !!!
mov ax, $CD MOD 3
    


> However, note that ROR and ROL can be build
> as a series of SHR/SHL, AND and OR

True, but with same "right" you could delete many other operators too.

#undef MOD
Post 08 Feb 2013, 10:09
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7795
Location: Kraków, Poland
Tomasz Grysztar
DOS386 wrote:
Would it be possible to add ROL and ROR into FASM? I miss them.
If you'd like to revive the discussion, I suggest to continue from this point: http://board.flatassembler.net/topic.php?p=18841#18841
MCD brought up what the problem is. I never got an idea for a nice solution (though I must confess that I did not put much effort into trying), but maybe you would propose something.
Post 08 Feb 2013, 11:50
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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
Tomasz Grysztar wrote:
revive the discussion, I suggest to continue from this point


Thanks ... it's the size problem and the infamous "infinite precision". I'd be happy with

ROL8
ROR8
ROL32
ROR32

as I don't have any better idea for now, and so far dealt with 8-bit and 32-bit ROL'ling stuff only.

Same for B.S.WAP: either make it 32-bit only, or make BSWAP32 and BSWAP64. BSWAP16 could be replaced by ROL16 (considering that CPU's don't support BSWAP16 at all Very Happy )
Post 08 Feb 2013, 12:46
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17658
Location: In your JS exploiting you and your system
revolution
DOS386 wrote:
(considering that CPU's don't support BSWAP16 at all Very Happy )
Sure they do:
Code:
xchg ah,al ;bswap16 ax    
Razz
Post 08 Feb 2013, 12:52
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