how count bits in macro ?

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Roman

Joined: 21 Apr 2012
Posts: 2019

Roman 07 May 2025, 07:29

fasmw 1.73
I want get last set-up bit.
For example 01001 last bit number is 3

Code:

;analog asm command bsr
macro getBtNum v { ... }

;in code
getBtNum 32 ;must get 5 bit
getBtNum 1 ;must get 0 bit
getBtNum 8 ;must get 3 bit

Last edited by Roman on 07 May 2025, 08:09; edited 1 time in total

07 May 2025, 07:29

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20759
Location: In your JS exploiting you and your system

revolution 07 May 2025, 07:42

bsr

Code:

display bsr 01001b + '0'

flat assembler  version 1.73.31  (16384 kilobytes memory)
3
1 passes, 0 bytes.

07 May 2025, 07:42

Roman

Joined: 21 Apr 2012
Posts: 2019

Roman 07 May 2025, 08:10

fasmw supported bsr ! wow ! Its cool.
Thanks.

07 May 2025, 08:10

Roman

Joined: 21 Apr 2012
Posts: 2019

Roman 07 May 2025, 08:51

How about ror in fasmw macro?
Or how implement ror in fasmw macro?

07 May 2025, 08:51

macomics

Joined: 26 Jan 2021
Posts: 1197
Location: Russia

macomics 07 May 2025, 08:57

Roman wrote:

How about ror in fasmw macro?

Code:

a = 7 shl 3
n = 3
a = 0xFFFFFFFF and (a shl (32-n)) and (a shr n) ; 32-bit ror
display a + '0', 13, 10

b = 1048576
k = 10
b = 0xFFFFFFFFFFFFFFFF and (b shr (64-k)) and (b shl k) ; 64-bit rol

c = 1 shl 32
i = 24
if i < 38
  c = 0x7FFFFFFFFF and (c shl (39-i)) and (c shr i) ; 39-bit ror
end if

07 May 2025, 08:57

Roman

Joined: 21 Apr 2012
Posts: 2019

Roman 07 May 2025, 09:15

I get zero.

Code:

n = 3
v = 6025
__@v1 = 0xFFFFFFFF and (v shl (32-n)) and (v shr n)
mov ecx,__@v1 ; get zero

must be 0x78900001

07 May 2025, 09:15

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20759
Location: In your JS exploiting you and your system

revolution 07 May 2025, 09:20

The shr and shl parts need to be ored together, then and with the 0xffffffff mask.

07 May 2025, 09:20

macomics

Joined: 26 Jan 2021
Posts: 1197
Location: Russia

macomics 07 May 2025, 09:27

Code:

macro display_int x { local ..u, ..v
  ..v = x
  ..u = 1
  while ..u < ..v
    ..u = ..u * 10
  end while
  if ..v = 0
    display '0'
  else
    while ..u > 1
      ..u = ..u / 10
      display '0' + ..v / ..u
      ..v = ..v - ..u * ( ..v / ..u )
    end while
  end if
  display ' '
}

a = 6020
n = 3
BIT_MASK = 0xFFFFFFFF
BIT_LENGTH = 32
a = ( BIT_MASK AND ( a shr ( BIT_LENGHT - n + 1 ))) OR ( BIT_MASK AND ( a shl n ))
display_int a
mov ecx, a

Code:

Last edited by macomics on 07 May 2025, 10:08; edited 1 time in total

07 May 2025, 09:27

Roman

Joined: 21 Apr 2012
Posts: 2019

Roman 07 May 2025, 09:32

Thanks.
How about rol ?

Last edited by Roman on 07 May 2025, 09:35; edited 1 time in total

07 May 2025, 09:32

macomics

Joined: 26 Jan 2021
Posts: 1197
Location: Russia

macomics 07 May 2025, 09:34

Roman wrote:

must be 0x78900001

n=3 ; bits => must be 0x1784 shl 3 = 0xBC20

07 May 2025, 09:34

Roman

Joined: 21 Apr 2012
Posts: 2019

Roman 07 May 2025, 09:36

macomics
How about rol ?

07 May 2025, 09:36

macomics

Joined: 26 Jan 2021
Posts: 1197
Location: Russia

macomics 07 May 2025, 09:39

Code:

use64
macro display_int x { local ..u, ..v
  ..v = x
  ..u = 1
  while ..u < ..v
    ..u = ..u * 10
  end while
  if ..v = 0
    display '0'
  else
    while ..u > 1
      ..u = ..u / 10
      display '0' + ..v / ..u
      ..v = ..v - ..u * ( ..v / ..u )
    end while
  end if
  display ' '
}

a = 6025
n = 12
BIT_MASK   = 0x7FFFFFFFFF
BIT_LENGTH = 1 + bsr BIT_MASK
a = ( BIT_MASK AND ( a shl ( BIT_LENGTH - n + 1 ))) OR ( BIT_MASK AND ( a shr n ))
display_int a
mov rcx, a

Code:

517811994625

or 0x7890000001

Last edited by macomics on 07 May 2025, 10:08; edited 1 time in total

07 May 2025, 09:39

macomics

Joined: 26 Jan 2021
Posts: 1197
Location: Russia

macomics 07 May 2025, 09:45

Roman wrote:

How about rol ?

rol and ror

07 May 2025, 09:45

Roman

Joined: 21 Apr 2012
Posts: 2019

Roman 07 May 2025, 09:47

ror wrong result.

Code:

n = 12
v = 6025
__@v1 = ( 0xFFFFFFFF AND ( v shr ( 32 - n ))) OR ( 0xFFFFFFFF AND ( v shl n ))

I get 1789000h but must be 7890001h

07 May 2025, 09:47

macomics

Joined: 26 Jan 2021
Posts: 1197
Location: Russia

macomics 07 May 2025, 09:50

Roman wrote:

ror wrong result.

correct

Last edited by macomics on 07 May 2025, 10:14; edited 2 times in total

07 May 2025, 09:50

Roman

Joined: 21 Apr 2012
Posts: 2019

Roman 07 May 2025, 09:51

macomics
Try for ror
n = 12
a = 6025

07 May 2025, 09:51

macomics

Joined: 26 Jan 2021
Posts: 1197
Location: Russia

macomics 07 May 2025, 10:02

Roman wrote:

Try
n = 12
v = 6025

correct

Last edited by macomics on 07 May 2025, 10:14; edited 1 time in total

07 May 2025, 10:02

macomics

Joined: 26 Jan 2021
Posts: 1197
Location: Russia

macomics 07 May 2025, 10:03

It is 39-bit ror. Use BIT_MASK = 0xFFFFFFFF for 32-bit and BIT_MASK = 0xFFFFF for 20-bit

07 May 2025, 10:03

macomics

Joined: 26 Jan 2021
Posts: 1197
Location: Russia

macomics 07 May 2025, 10:12

Code:

use64
macro display_int x { local ..u, ..v
  ..v = x
  ..u = 1
  while ..u < ..v
    ..u = ..u * 10
  end while
  if ..v = 0
    display '0'
  else
    while ..u > 1
      ..u = ..u / 10
      display '0' + ..v / ..u
      ..v = ..v - ..u * ( ..v / ..u )
    end while
  end if
  display ' '
}

a = 6025
n = 12
BIT_MASK   = 0x7FFFFFFFFF
BIT_LENGTH = 1 + bsr BIT_MASK
a = ( BIT_MASK AND ( a shl ( BIT_LENGTH - n + 1 ))) OR ( BIT_MASK AND ( a shr n ))
display_int a
mov rcx, a

Code:

517811994625

That's not how I count the bits in the calculator. That's right

Description:
Filesize:	124.23 KB
Viewed:	5402 Time(s)

07 May 2025, 10:12

Roman

Joined: 21 Apr 2012
Posts: 2019

Roman 07 May 2025, 10:14

I do this for ror:

Code:

use32
n = 12
v = 6025
BIT_MASK = 0xFFFFFFFF 
__@v1 = ( BIT_MASK AND ( v shr ( 1 + bsr BIT_MASK - n ))) OR ( BIT_MASK AND ( v shl n ))
mov eax,__@v1 ;IDA Pro show 1789000h

I get 1789000h but must be 78900001h

Code:

mov eax,6025
ror eax,12 ;IDA Pro show 78900001h

07 May 2025, 10:14

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