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avr: provide polynomial for crc function.

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This commit is contained in:
Martin Preuss
2024-09-12 11:44:54 +02:00
parent c055ee6cc2
commit a10cd8293b
2 changed files with 8 additions and 7 deletions
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14
avr/modules/com2/crc.asm
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@@ -51,16 +51,14 @@ com2CheckMessageInBuffer_error:
; --------------------------------------------------------------------------- ; ---------------------------------------------------------------------------
; com2CalcMsgChecksum ; @routine com2CalcMsgChecksum
; ;
; calc checksum from msg buffer (except crc byte) ; calc checksum from msg buffer (except crc byte)
; ;
; IN: ; @return r16 crc8 checksum
; - X : pointer to packet buffer (points to checksum byte upon return) ; @return X points to position of checksum byte
; OUT: ; @param X pointer to packet buffer (points to checksum byte upon return)
; - r16: crc8 checksum ; @clobbers R16, R18, R19, (R17, R20, X)
; - X : points to position of checksum byte
; MODIFIED REGS: R16, R18, (R17, R20, X)
com2CalcMsgChecksum: com2CalcMsgChecksum:
adiw xh:xl, COM2_MSG_OFFS_MSGLEN adiw xh:xl, COM2_MSG_OFFS_MSGLEN
@@ -68,6 +66,8 @@ com2CalcMsgChecksum:
sbiw xh:xl, COM2_MSG_OFFS_MSGLEN sbiw xh:xl, COM2_MSG_OFFS_MSGLEN
inc r18 ; account for dest address inc r18 ; account for dest address
inc r18 ; account for msg len byte inc r18 ; account for msg len byte
ldi r19, COM2_CRC8_POLYNOMIAL ; polynomial
rjmp crc8Calc ; (R16, R17, R18, R20, X) rjmp crc8Calc ; (R16, R17, R18, R20, X)
; @end

1
avr/modules/com2/defs.asm
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@@ -45,3 +45,4 @@
.equ COM2_ERROR_COLLISION = 5 .equ COM2_ERROR_COLLISION = 5
.equ COM2_CRC8_POLYNOMIAL = 0x97 ; HD=4 up to 119 bytes, e.g. detects all 1 to 3 bit errors