fasm 1.67.21 bug not in 1.64?

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lazer1

Joined: 24 Jan 2006
Posts: 185

lazer1 27 Mar 2007, 20:29

all the code is now changed, I've now compiled everything with
the new version of fasm and its all functioning fine, Cool

27 Mar 2007, 20:29

Hayden

Joined: 06 Oct 2005
Posts: 132

Hayden 28 Mar 2007, 03:36

In regards to chaging every jump call use an editor that has
"find/replace all"

ps. I've found that it is allways best to use full syntax with memory operands 'cause you can always read it easily and you xan allways see where its jumping, calling or read/write from

especialy in the case of 16bit segment program

28 Mar 2007, 03:36

rugxulo

Joined: 09 Aug 2005
Posts: 2341
Location: Usono (aka, USA)

rugxulo 31 Mar 2007, 03:12

lazer1 wrote:

one problem I found is that there is no form of "loop label"
which both the earlier fasm and the current fasm accept,

the earlier fasm doesnt accept "loop dword label" but
accepts eg "jmp dword label" and "call dword label",

FASM.TXT wrote:

"loop" instructions automatically decrement CX (or ECX) and terminate the
loop (don't transfer the control) when CX (or ECX) is zero. It uses CX or ECX
whether the current code setting is 16-bit or 32-bit, but it can be forced to
us CX with the "loopw" mnemonic or to use ECX with the "loopd" mnemonic.

lazer1 wrote:

I got around that by replacing "loop label" by

sub cx, 1
jnz dword label

(I dont use "dec" as this code isnt speed critical, I
generally avoid the unusual opcodes of 16 bit. In fact
I will probably avoid loop in future as it is too complicated
to remember: does it loop if cx goes to 0 or from 0?
yes I know the answer is to 0, but I have to look that up
which wastes time. )

dec is supposedly slower on a P4 than sub anyways.

31 Mar 2007, 03:12

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8266
Location: Kraków, Poland

Tomasz Grysztar 31 Mar 2007, 03:51

rugxulo: Those are four different instructions:

Code:

loopw word label ; uses CX and IP, no prefix in 16-bit mode
loopw dword label ; uses CX and EIP, prefix 66h in 16-bit mode
loopd word label ; uses ECX and IP, prefix 67h in 16-bit mode
loopd dword label ; uses ECX and EIP, both 66h and 67h prefixes in 16-bit mode

See also the announcement notes of the fasm's version that introduced the correction of jumps handling.

PS. When I write "uses IP", it means actually that high-order 16 bits of EIP get zeroed.

31 Mar 2007, 03:51

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 31 Mar 2007, 05:15

You found the thread I was talking about Very Happy

31 Mar 2007, 05:15

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