PIC 滚动码的解码程序

liyf · 发表于 2012-1-27 14:12:53

???? 摘要：PIC单片机滚动码的解码程序

　　#include
　　;
　　global DECRYPT
　　global KEY0,KEY1,KEY2,KEY3,KEY4,KEY5,KEY6,KEY7
　　global CSR0,CSR1,CSR2,CSR3,CSR4,CSR5,CSR6,CSR7,CSR8
　　;
　　#define? HOP1 CSR0??? ; ﹚竡 HOP1"4 单 CSR1"4
　　#define? HOP2 CSR1
　　#define? HOP3 CSR2
　　#define? HOP4 CSR3
　　#define? MAX_CODE_LENGTH .72
　　#define? CODE_LENGTH .66
　　;
　　UDATA_SHR???? ; Difine CSR0:CSR7 ON Share memory
　　CSR0? res 1????? ; Hopping Code 钡Μ纗既竟 (LSB)
　　CSR1? res 1
　　CSR2? res 1
　　CSR3? res 1
　　CSR4? res 1
　　CSR5? res 1
　　CSR6? res 1
　　CSR7? res 1
　　CSR8? res 1????? ; Hopping Code 钡Μ纗既竟 (MSB)
　　;
　　Encrypt_Data UDATA 0x20
　　KEY0? res 1????? ; 64-bit 秆盞じン戈 (LSB)
　　KEY1? res 1
　　KEY2? res 1
　　KEY3? res 1
　　KEY4? res 1
　　KEY5? res 1
　　KEY6? res 1
　　KEY7? res 1
　　;
　　UDATA
　　CNT0? res 1
　　CNT1? res 1
　　HOP_LENGTH res 1
　　MASK? res 1
　　KEELOQ_temp res 1
　　;
　　;
　　KEELOQ_CODE CODE
　　;
　　;*****************************************************
　　;**** Rotate CSRs regiSTer right 1 bit
　　;*****************************************************
　　ROT_CSRs
　　RRF? CSR8,F
　　RRF???? CSR7,F
　　RRF???? CSR6,F
　　RRF???? CSR5,F
　　RRF???? CSR4,F
　　RRF???? CSR3,F
　　RRF???? CSR2,F
　　RRF???? CSR1,F
　　RRF???? CSR0,F
　　return
　　;
　　;
　　;
　　;
　　;****************************************************************
　　;
　　; FUNCTION????? : DECRYPT ()
　　;
　　; DESCRIPTION?? : DECRYPTS 32 BIT [HOP1:HOP4] USING [CSR0:CSR7]
　　;
　　;****************************************************************
　　DECRYPT
　　BANKSEL CNT1
　　MOVLW?? (.11+1)???????? ; OUTER LOOP 11+1 TIMES
　　MOVWF?? CNT1?????????? ; OUTER LOOP 11+1 TIMES
　　DECRYPT_OUTER
　　MOVLW?? .48???????????? ; INNER LOOP 48 TIMES
　　MOVWF?? CNT0?????????? ; INNER LOOP 48 TIMES
　　DECRYPT_INNER
　　CLRWDT???? ; RESET WATCHDOG TIMER
　　MOVFW?? CNT1?? ; LAST 48 LOOPS RESTORE THE KEY
　　XORLW?? .1????????????? ; LAST 48 LOOPS RESTORE THE KEY
　　btfsc STATUS,Z??????? ; LAST 48 LOOPS RESTORE THE KEY
　　GOTO??? ROTATE_KEY????? ; LAST 48 LOOPS RESTORE THE KEY
　　; THE LOOKUP TABLE IS COMPRESSED INTO IN 4 BYTES TO SAVE SPACE
　　; USE THE 3 LOW INDEX BITS TO MAKE UP AN 8-BIT BIT MASK
　　; USE THE 2 HIGH INDEX BITS TO LOOK UP THE VALUE IN THE TABLE
　　; USE THE BIT MASK TO ISOLATE THE CORRECT BIT IN THE BYTE
　　; PART OF THE REASON FOR THIS SCHEME IS BECAUSE NORMAL TABLE
　　; LOOKUP REQUIRES AN ADDITIONAL STACK LEVEL
　　bcf STATUS,C???????? ; CLEAR CARRY (FOR THE LEFT SHIFT)
　　MOVLW?? .1????????????? ; INITIALISE MASK = 1
　　BTFSC?? HOP3,3??????? ; SHIFT MASK 4X IF BIT 2 SET
　　MOVLW?? B'00010000'???? ; SHIFT MASK 4X IF BIT 2 SET
　　MOVWF?? MASK??????????? ; INITIALISE MASK = 1
　　BTFSS?? HOP2,0??????? ; SHIFT MASK ANOTHER 2X IF BIT 1 SET
　　GOTO??? $+3
　　RLF???? MASK,F
　　RLF???? MASK,F
　　BTFSC?? HOP1,0??????? ; SHIFT MASK ANOTHER 1X IF BIT 0 SET
　　RLF???? MASK,F
　　; MASK HAS NOW BEEN SHIFTED 0-7 TIMES ACCORDING TO BITS 2:1:0
　　MOVlw HIGH TABLE
　　MOVwf PCLATH
　　MOVlw LOW TABLE
　　MOVwf KEELOQ_Temp
　　MOVLW?? 0?????????????? ; TABLE INDEX = 0
　　BTFSC?? HOP4,1
　　IORLW?? .2????????????? ; IF BIT 3 SET ADD 2 TO THE TABLE INDEX
　　BTFSC?? HOP4,6
　　IORLW?? .4????????????? ; IF BIT 4 SET ADD 4 TO THE TABLE INDEX
　　addwf KEELOQ_Temp,W
　　btfsc STATUS,C
　　incf PCLATH,F
　　MOVwf PCL??????????? ; ADD THE INDEX TO THE PROGRAM COUNTER
　　;? [ MUST BE IN LOWER HALF OF PAGE ]
　　TABLE
　　MOVLW?? 0x2E??????????? ; BITS 4:3 WERE 00
　　GOTO??? TABLE_END?????? ; END OF LOOKUP
　　MOVLW?? 0x74??????????? ; BITS 4:3 WERE 01
　　GOTO??? TABLE_END?????? ; END OF LOOKUP
　　MOVLW?? 0x5C??????????? ; BITS 4:3 WERE 10
　　GOTO??? TABLE_END?????? ; END OF LOOKUP
　　MOVLW?? 0x3A??????????? ; BITS 4:3 WERE 11
　　TABLE_END
　　ANDWF?? MASK,1????????? ; ISOLATE THE CORRECT BIT
　　MOVLW?? 0?????????????? ; COPY THE BIT TO BIT 7
　　btfss STATUS,Z??????? ; COPY THE BIT TO BIT 7
　　MOVLW?? B'10000000'???? ; COPY THE BIT TO BIT 7
　　XORWF?? HOP2,W????? ; ONLY INTERESTED IN BIT HOP2,7
　　XORWF?? HOP4,W????? ; ONLY INTERESTED IN BIT HOP4,7
　　XORWF?? KEY1,W?? ; ONLY INTERESTED IN BIT KEYREG1,7
　　MOVWF?? MASK??????????? ; STORE W TEMPORARILY (WE NEED BIT 7)
　　RLF???? MASK,F????????? ; LEFT ROTATE MASK TO GET BIT 7 INTO CARRY
　　RLF???? HOP1,F????????? ; SHIFT IN THE NEW BIT
　　RLF???? HOP2,F
　　RLF???? HOP3,F
　　RLF???? HOP4,F
　　ROTATE_KEY
　　bcf STATUS,C?? ; CLEAR CARRY
　　BTFSC?? KEY7,7??????? ; SET CARRY IF LEFTMOST BIT SET
　　bsf STATUS,C???????? ; SET CARRY IF LEFTMOST BIT SET
　　RLF???? KEY0,F????????? ; LEFT-ROTATE THE 64-BIT KEY
　　RLF???? KEY1,F
　　RLF???? KEY2,F
　　RLF???? KEY3,F
　　RLF???? KEY4,F
　　RLF???? KEY5,F
　　RLF???? KEY6,F
　　RLF???? KEY7,F
　　DECFSZ? CNT0,F????????? ; INNER LOOP 48 TIMES
　　GOTO??? DECRYPT_INNER?? ; INNER LOOP 48 TIMES
　　DECFSZ? CNT1,F????????? ; OUTER LOOP 12 TIMES (11+1 TO RESTORE KEY)
　　GOTO??? DECRYPT_OUTER?? ; OUTER LOOP 12 TIMES (11+1 TO RESTORE KEY)
　　RETLW?? 0?????????????? ; RETURN
　　?

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