F28335 carry bit

Bryan Lu

Hi TI

Is there any body can help me?

I currently want to read Carry bit of ST0. I read SPRU430E- the assembly lanuage instructions, I cannot find any instruction can read the Carry bit.

Actually I want to get every bit of a 32bit data.

I plan to use:

ROL ACC then read the Carry bit to get every single bit data.

this is why i need to read Carry bt.

who can help me? thanks

over 12 years ago

0 Bill Finger over 12 years ago

Genius 3735 points

Mr. Lu:

I would use the fast conditional branch:

BF #label, C

; do stuff with C = 0

BF #done

label:

; do stuff with C = 1

done:

BTW, there are probably more efficient ways to do what you really want to do, but here you are.

Regards,

Bill

0 David M. Alter over 12 years ago

TI__Guru 61235 points

Bryan,

Bill suggested one approach. Beyond that, if you want to read any of the bits in the ST0 or ST1 register (e.g., C bit), you use PUSH ST0 (or PUSH ST1) to push the register onto the stack. You can then POP it into the accumulator and get to the bit(s) you are interested in. I don't think you can do this from C. You need to use assembly.

Regards,

David

0 Bryan Lu over 12 years ago in reply to Bill Finger

Prodigy 40 points

thanks Bill. I wil try to use BF instruction

0 Bryan Lu over 12 years ago in reply to David M. Alter

Prodigy 40 points

thanks David. it's another good approach.

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F28335 carry bit