recv byte count

[ecube]

I want to log a days worth of recieved bytes via the function recv, I don't think dword will hold it, how should I approach this?

[jj2007]

Either use qwords, or count kBytes...

[Shantanu Gadgil]

I too think qwords should do ... for now  :wink ( ffff ffff ffff ffff [hex] == 18,446,744,073,709,551,615 [dec])

I think that many bytes per day would be enough. (Although, "enough" is never really enough!!!  :bdg )

Ok getting too philosophical ... maybe!

I think the following code might be useful:

Code Select Expand

mov     eax, dwBytesDownloadedLow
mov     edx, dwBytesDownloadedHigh
;============================
add     eax, dwBytesReceived   ;from the recv function
adc     edx, 0
;============================
mov     dwBytesDownloadedLow, eax
mov     dwBytesDownloadedHigh, edx


Then use the 64-bit pair of High:Low to output the number in "string" or KB or MB or whatever!

HTH,
Shantanu

[Tedd]

Code Select Expand


.data?
count_lo    DWORD ?
count_hi    DWORD ?

.code
      :
    mov eax,bytes_recvd
    add count_lo,eax
    adc count_hi,0
      :


You could keep adding 'adc' as many times as you like, but I don't think you'll get a QWORD of bytes in a day (~ 194TB/s for 24hours!!)
..or week :lol

[ecube]

you said use a qword but you're examples you're still using a 2 dwords to represent a qword and just filling 1 of the dwords with the count. doesn't the defeat the purpose?

[Tedd]

The magic part is the ADC :wink

recv gives a 32-bit count of the bytes received in that call.
You take that value and add it onto count_lo - that only requires 32 bits until the total overflows...
When an addition overflows, the carry flag is set (the maximum an addition can overflow is only one extra bit.)
Then you add-with-carry onto count_hi. If there was no bit to carry this will do nothing (count_hi+0+0), but when the carry-flag is set the extra bit will be added on (count_hi+0+1) -- which, in effect, makes count_hi:count_lo behave as the 64-bit value you want.
And you can chain together as many dwords as you want, just by following with extra adc instructions.

[ecube]

that's pretty neat :) thanks for explaining it to me tedd, I never seen anyone intentionally overflow something, but if works, great :D

[Tedd]

That is how the instructions are designed to work :wink
You can do a similar thing for 'long' subtraction, using SUB/SBB