Grahams working code with parity:
*note: two macros used, I find it pretty deadly doing literal to file
shifts and file to file shifts with seperate code lines. macros are
"BTG" and "WMOVL"

(even parity)


;BASIC SETUP INFO:

BAUD_LOOPS      EQU     D'251'  ;1200 BAUD @ 5.58 MHz
ASCII           (SPARE DATA RAM VARIABLE FOR TX DATA)
DEL_A           (SPARE DATA RAM VARIABLE)
TASK_FLAGS      (SPARE DATA RAM VARIABLE)
#DEFINE         _TX_SCI PORTB,0  ;( REPLACE AS APPLICABLE )

;macro working variables:

MV1     EQU     0
MV2     EQU     0

macro definitions:
WMOVL   MACRO   MV1,MV2 ;       LITERAL TO FILE
        NOEXPAND
        MOVLW   MV1
        MOVWF   MV2
        ENDM

WMOVF   MACRO   MV1,MV2 ;       FILE TO FILE
        NOEXPAND
        MOVF    MV1,W
        MOVWF   MV2
        ENDM

BTG     MACRO   MV1,MV2 ;       BIT TOGGLE
        NOEXPAND
        MOVLW   1 << MV2
        XORWF   MV1,F
        ENDM

;======================================

;transmit code:

ASCII_TX_OUT
START_BIT
        CALL    ASYNC_H
TX_ASCII
        BCF     TASK_FLAGS,PARITY
        WMOVL   07,DEL_A        ; (7 BITS DATA, " MOVLW D'07' ",
                                ;               " MOVWF DEL_A " )
EACH_BIT
        BTFSC   ASCII,0
        GOTO    BZZ_HOT
        CALL    ASYNC_H
        GOTO    DUN_BZZ
BZZ_HOT
        CALL    ASYNC_L
        BTG     TASK_FLAGS,PARITY       ; (BTG IS MACRO,  " MOVLW 1 << PARITY ",
                                        ;                 " XORWF       MV1,F "
)
DUN_BZZ
        RRF     ASCII,F
        DECFSZ  DEL_A,F
        GOTO    EACH_BIT
SEND_PARITY
        BTFSC   TASK_FLAGS,PARITY
        GOTO    BZZ_HOTP
        CALL    ASYNC_H
        GOTO    DUN_BZZP
BZZ_HOTP
        CALL    ASYNC_L
DUN_BZZP
        CALL    ASYNC_L
        RETURN

;==========================================

ASYNC_L
        WMOVL   BAUD_LOOPS,CYCLES
        BSF     _TX_SCI
LTL_LOOP
        DECFSZ  CYCLES,F
        GOTO    LTL_LOOP
        RETURN

;==========================================

ASYNC_H
        WMOVL   BAUD_LOOPS,CYCLES
        BCF     _TX_SCI
HTL_LOOP
        DECFSZ  CYCLES,F
        GOTO    HTL_LOOP
        RETURN

;==========================================


James & Ili wrote:
>
> I remember a list discussion about parity generation a while back
> but a search of the piclist archive doesn't turn it up. Could someone
> share with me either the code, a pointer to the code or just the
> theory
> of the code please ??
>
> Thanks in advance !!
>
> James & Ili
> Irving, TX. 75038
James & Ili wrote:
>
> I remember a list discussion about parity generation a while back
> but a search of the piclist archive doesn't turn it up. Could someone
> share with me either the code, a pointer to the code or just the
> theory
> of the code please ??
>
> Thanks in advance !!
>
> James & Ili
> Irving, TX. 75038