MMX convert text to byte value.

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Roman

Joined: 21 Apr 2012
Posts: 2132

Roman 08 Sep 2026, 16:38

I write code but its big code. I want three or 4 asm commands.

Code:

txtV db '16' ; i have many numbers
intV db 0

tt2 db 48,48,48,48
tt3 db 10,0,0,0 

;do some mmx operations and get intV=16

movd mm0,dword [txtV]
psubb mm0,qword [tt2]
movd ecx,mm0
pmullw mm0,qword[tt3]
movd eax,mm0
add al,ch 
mov [intV],al ;intV=16

08 Sep 2026, 16:38

Roman

Joined: 21 Apr 2012
Posts: 2132

Roman 08 Sep 2026, 18:12

Code:

ttt db '16'
intV db 0

        sub word [ttt],0x3030
        movzx eax,byte [ttt]
        imul eax,10
        add al,[ttt+1]
        mov [intV],al

08 Sep 2026, 18:12

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 21097
Location: In your JS exploiting you and your system

revolution 08 Sep 2026, 18:30

Dor the limited set of two digit bcd inputs.

Code:

mov ax,word[bcd]
sub ax,'00'
imul ax,0x10a
mov [result],ah

bcd db '16'
result db ?

There ia also aad designed exactly for this task.

08 Sep 2026, 18:30

Roman

Joined: 21 Apr 2012
Posts: 2132

Roman 08 Sep 2026, 18:50

Quote:

mov ax,word[bcd]
sub ax,'00'
imul ax,0x10a
mov [result],ah

Wrong result.

08 Sep 2026, 18:50

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 21097
Location: In your JS exploiting you and your system

revolution 08 Sep 2026, 18:53

Wrong multiplier.

Code:

mov ax,word[bcd]
sub ax,'00'
imul ax,0xa01
mov [result],ah

bcd db '16'
result db ?

08 Sep 2026, 18:53

Roman

Joined: 21 Apr 2012
Posts: 2132

Roman 08 Sep 2026, 19:12

Intel was supposed to do it this way AAD

Code:

aad al,ah,0x30  ;= sub al,0x30 and sub ah,0x30 and p1*10+p2.  p1=al and p2=ah

08 Sep 2026, 19:12

Roman

Joined: 21 Apr 2012
Posts: 2132

Roman 09 Sep 2026, 07:04

from 0 to 9999

Code:

ttt db '4687'
intVal dw 0

        movzx eax,word [ttt]
        sub ax,'00'
        imul ax,0xa01
        sub al,al
        imul eax,100

        movzx ecx,word [ttt+2]
        sub cx,'00'
        imul cx,0xa01
        sub cl,cl
        add eax,ecx     ;as integer value. EAX=0x00124F00
        shr eax,8
        mov [intVal],ax ;eax=4687

09 Sep 2026, 07:04

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 21097
Location: In your JS exploiting you and your system

revolution 09 Sep 2026, 12:09

Now convert to MMX

09 Sep 2026, 12:09

Roman

Joined: 21 Apr 2012
Posts: 2132

Roman 09 Sep 2026, 13:45

Quote:

Now convert to MMX

I not any idea how do this.
especially this imul ax,0xa01

09 Sep 2026, 13:45

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 21097
Location: In your JS exploiting you and your system

revolution 09 Sep 2026, 14:15

Roman wrote:

... imul ax,0xa01

PMULLW

09 Sep 2026, 14:15

Roman

Joined: 21 Apr 2012
Posts: 2132

Roman 09 Sep 2026, 16:24

I do this but code size as prevision

Code:

 tt db '4687'  ;this variant good for two numbers like as '4687' and '1635'
 tt2 db 48,48,48,48
 tt3 dw 0xa01,0xa01
 tt4 db 0,255,0,255,0,0,0,0
result dd 0,0


     movd mm0,dword [tt]
     psubb mm0,qword [tt2]
     pmullw mm0,qword[tt3]
     pand mm0,qword [tt4]
     movd ecx,mm0
     shr ecx,8
     movzx eax,cl
     imul eax,100
     shr ecx,16
     add ax,cx              ;eax=4687

;second variant
     movd   mm0,dword [tt]
     psubb  mm0,qword [tt2]
     pmullw mm0,qword[tt3]
     pand mm0,qword [tt4]
     movq qword [result],mm0
     movzx eax,byte [result+1]
     imul eax,100
     add ax,word [result+3]    ;eax=4687

;theerd variant
 tt db '96878687'
 tt2 db 48,48,48,48, 48,48,48,48
 tt3 dw 0xa01,0xa01,0xa01,0xa01         
 tt4 db 0,255,0,255,0,255,0,255

 
     movq mm0,qword [tt]
     psubb mm0,qword [tt2]
     pmullw mm0,qword[tt3]
     pand mm0,qword [tt4]
     movq qword [result],mm0
     movzx eax,byte [result+1]
     imul eax,100
     add ax,word [result+3]
     imul eax,10000

     movzx ecx,byte [result+5]
     imul ecx,100
     add cx,word [result+7]

     add eax,ecx ;eax=96878687 integer

Last edited by Roman on 11 Sep 2026, 05:37; edited 7 times in total

09 Sep 2026, 16:24

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 21097
Location: In your JS exploiting you and your system

revolution 09 Sep 2026, 16:50

Multiplying the constant 100 can be done inside MMX.

09 Sep 2026, 16:50

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