Checking a byte for odd parity

[Snowblind]

Im interfacing a 16c84 with a AT keyboard I have it receiving the keyboard scan code and parity bit fine.

I now want to check the parity bit for correctness. I'm currently iqnoring it

The way I understand odd parity is counts all the one in a byte and makes the parity a 0 or 1 to make the byte and the parity bit have a odd number of ones

I also plan on sending keyboard scan codes to the computer.

So Im hoping one of you guys that is better at software than I can show me how to check and generate a parity bit from a byte
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This message was ported from CCS's old forum
Original Post ID: 1299

[Tomi]

Try this:

char GetParity(char be)
{
be ^= be >> 4;
be ^= be >> 2;
be ^= be >> 1;
be &= 0x01;
return (be);
}

Output: 0->Even, 1->Odd


:=Im interfacing a 16c84 with a AT keyboard I have it receiving the keyboard scan code and parity bit fine.
:=
:=I now want to check the parity bit for correctness. I'm currently iqnoring it
:=
:=The way I understand odd parity is counts all the one in a byte and makes the parity a 0 or 1 to make the byte and the parity bit have a odd number of ones
:=
:=I also plan on sending keyboard scan codes to the computer.
:=
:=So Im hoping one of you guys that is better at software than I can show me how to check and generate a parity bit from a byte
___________________________
This message was ported from CCS's old forum
Original Post ID: 1302

[Snowblind]

Thank you,

Works great I had to add a line to get the output i wanted

after this line be &= 0x01; I put a be ^= 0x01;

You me past the bit shifting i have problems getting that down





:=Try this:
:=
:=char GetParity(char be)
:={
:=be ^= be >> 4;
:=be ^= be >> 2;
:=be ^= be >> 1;
:=be &= 0x01;
:=return (be);
:=}
:=
:=Output: 0->Even, 1->Odd
:=
:=
:=:=Im interfacing a 16c84 with a AT keyboard I have it receiving the keyboard scan code and parity bit fine.
:=:=
:=:=I now want to check the parity bit for correctness. I'm currently iqnoring it
:=:=
:=:=The way I understand odd parity is counts all the one in a byte and makes the parity a 0 or 1 to make the byte and the parity bit have a odd number of ones
:=:=
:=:=I also plan on sending keyboard scan codes to the computer.
:=:=
:=:=So Im hoping one of you guys that is better at software than I can show me how to check and generate a parity bit from a byte
___________________________
This message was ported from CCS's old forum
Original Post ID: 1308