boot51.a51

一份51的编译程序,dos版本的. 英文名字MCS-51 Microcontroller Family Macro Assembler

        ;the UART and returns the binary value in A.
        ;The checksum in R1 is updated accordingly.
        ;(In case of error the carry flag is set.)
        ;NEXTB changes only registers A, B, R1 and R7.
        CALL CONIN      ;read first hex digit
        CALL NIBBLE     ;convert it to 4-bit binary
        JC NEXTBR       ;stop, if error
        SWAP A          ;otherwise move it to high order nibble
        MOV R7,A        ;and save it
        CALL CONIN      ;read second hex digit
        CALL NIBBLE     ;convert it to 4-bit binary
        JC NEXTBR       ;stop, if error
        ORL A,R7        ;join both nibbles
        XCH A,R1        ;add the whole byte
        ADD A,R1        ;to the checksum
        XCH A,R1
        CLR C           ;no error
NEXTBR: RET             ;finished, carry set if error

EIN16:  ;starting from the current line position R0, a 16-bit
        ;hex number is read from the command line buffer, and
        ;converted to a binary number which is returned in R4/R5.
        ;If no error was detected A=0 on return, A<>0 otherwise.
        MOV R6,#4       ;up to 4 digits
        CALL HEX16      ;convert to binary
        JNZ EIN16F      ;error, if garbage
        CALL NIXMER     ;check for end of line
EIN16F: RET             ;if garbage, error: A<>0

HEX16:  ;starting from the current line position R0, a 16-bit
        ;hex number with up to R6 digits is read from the line
        ;buffer and converted to a binary number which is
        ;returned in R4/R5.
        ;If no error was detected A=0 on return, A<>0 otherwise.
        MOV A,@R0       ;read character
        JZ HEX16F       ;error, if 0
        CJNE A,#' ',HEX161
        INC R0          ;skip leading blanks
        JMP HEX16
HEX161: MOV R4,#0       ;R4/R5 = 0
        MOV R5,#0
        CALL NIBBLE     ;convert hex digit
        JC HEX16F       ;error, when failed
        CALL SHIFT4     ;shift 4 bits into R4/R5 from the right side
        INC R0          ;next character
        DEC R6
HEX162: MOV A,@R0       ;read character
        CALL NIBBLE     ;convert to hex digit
        JC HEX16R       ;when failed, finished
        CALL SHIFT4     ;shift 4 bits into R4/R5 from the right side
        INC R0          ;next character
        DJNZ R6,HEX162  ;convert up to 4 hex digits
HEX16R: CLR A           ;o.k., number in R4/R5
        RET
HEX16F: MOV A,#0FFH     ;conversion error
        RET

NIBBLE: ;converts the hex digit in A into a 4-bit binary number
        ;which is returned in A. When the character is no hex
        ;digit, the carry flag is set on return.
        ;NIBBLE only changes registers A and B.
        CALL UPCASE     ;convert character to upper case
        MOV B,A         ;and save it
        CLR C           ;is character < 0 ?
        SUBB A,#'0'
        JC NIBBLR       ;then error
        MOV A,#'F'      ;is character > F ?
        SUBB A,B
        JC NIBBLR       ;then error, too
        MOV A,B         ;is character <= 9 ?
        SUBB A,#('9'+1)
        JC NIBBL1       ;then decimal digit
        MOV A,B         ;is character >= A ?
        SUBB A,#'A'
        JC NIBBLR       ;if not, error
NIBBL1: ADD A,#10       ;calculate binary number
        CLR C           ;digit converted correctly
NIBBLR: RET

SHIFT4: ;shifts a 4-bit binary number in A into register
        ;pair R4/R5 (HI/LO) from the right side.
        SWAP A          ;transfer nibble 4 bits to the left
        MOV R7,#6       ;Please do not ask for explaining THIS!
SHIFT0: RLC A           ;                                 ====
        XCH A,R5
        RLC A
        XCH A,R4
        DJNZ R7,SHIFT0
        RET

UPCASE: ;If the character in A is a lower case letter, it
        ;is converted to upper case and returned in A again.
        ;Otherwise it will be left unchanged.
        ;UPCASE only changes registers A and B.
        MOV B,A
        CLR C
        SUBB A,#'a'     ;is character < a ?
        JC UPCRET       ;then leave it unchanged
        MOV A,B
        SUBB A,#('z'+1) ;is character > z ?
        JNC UPCRET      ;then leave it unchanged, too
        ADDC A,#'Z'     ;otherwise convert it to upper case
        MOV B,A
UPCRET: MOV A,B
        RET

NEWLIN: ;outputs a new line.
        MOV A,#CR
        CALL CONOUT
        MOV A,#LF
        CALL CONOUT
        RET

STRING: ;String output: start address in DPTR, terminated with 0.
        ;STRING only changes registers DPTR and A.
        CLR A
        MOVC A,@A+DPTR
        JZ STRRET
        CALL CONOUT
        CALL WMSEC      ;Slow down output speed to about 9600 Baud!
        INC DPTR
        JMP STRING
STRRET: RET

CONOUT: ;output character in A.
        JNB TI,CONOUT   ;wait for UART output buffer to become clear
        CLR TI
        MOV SBUF,A      ;output character
        RET

CONIN:  ;read character and return it in A.
        JNB RI,CONIN
        MOV A,SBUF
        CLR RI
        ANL A,#07FH     ;mask parity (if any)
        RET

CONOST: ;output status: A=FF if ready, A=0 if not ready
        CLR A
        JNB TI,OSTRET   ;wait for UART output buffer to become clear
        DEC A
OSTRET: RET

CONIST: ;input status: A=FF if character received, A=0 if not
        CLR A
        JNB RI,ISTRET   ;no character received
        DEC A
ISTRET: RET

WMSEC:  ;about 1 ms delay
        PUSH AR6
        PUSH AR7
        MOV R6,#HIGH(TIMEBASE)
        MOV R7,#LOW(TIMEBASE)
WMSEC1: DJNZ R7,WMSEC1
        DJNZ R6,WMSEC1
        POP AR7
        POP AR6
        RET

DELAY:  ;wait for CHARTIME ms!
        ;CHARTIME is calculated to last for one byte sent by the UART.
        ;DELAY changes registers R6 and R7.
        MOV R6,#HIGH(CHARTIME)
        MOV R7,#LOW(CHARTIME)
DELAY1: CALL WMSEC              ;1 ms
        DJNZ R7,DELAY1
        DJNZ R6,DELAY1
        RET


        IFDEF INTEL8051
        ;baudrate generator timer 1

INITBG: ;start baudrate generator timer 1
        MOV  TCON,#0
        MOV  TMOD,#020H
        MOV  TH1,#RELOAD
        ANL  PCON,#07FH
        ORL  PCON,#SMOD
        SETB TR1
        RET

STOPBG: ;stop baudrate generator timer 1
        CLR  A
        MOV  TCON,A
        MOV  TMOD,A
        MOV  TH1,A
        MOV  TL1,A
        ANL  PCON,#07FH
        RET

        ENDIF


        IFDEF INTEL8052
        ;baudrate generator timer 2

        T2CON   DATA 0C8H
        RCAP2L  DATA 0CAH
        RCAP2H  DATA 0CBH
        TR2     BIT 0CAH

INITBG: ;start baudrate generator timer 2
        MOV  T2CON,#030H
        MOV  RCAP2H,#HIGH(RELOAD)
        MOV  RCAP2L,#LOW(RELOAD)
        SETB TR2
        RET

STOPBG: ;stop baudrate generator timer 2
        CLR  A
        MOV  T2CON,A
        MOV  RCAP2H,A
        MOV  RCAP2L,A
        RET

        ENDIF


        IFDEF SAB80535
        ;internal 80535 baudrate generator

        BD   BIT 0DFH

INITBG: ;start internal 80535 baudrate generator
        ANL  PCON,#07FH
        ORL  PCON,#SMOD
        SETB BD
        RET

STOPBG: ;stop internal 80535 baudrate generator
        CLR  BD
        ANL  PCON,#07FH
        RET

        ENDIF


        IFDEF SAB80C515A
        ;internal 80C535A baudrate generator

        SRELH   DATA 0BAH
        SRELL   DATA 0AAH
        BD      BIT  0DFH

INITBG: ;start internal 80C515A baudrate generator
        ANL  PCON,#07FH
        ORL  PCON,#SMOD
        MOV  SRELH,#HIGH(RELOAD)
        MOV  SRELL,#LOW(RELOAD)
        SETB BD
        RET

STOPBG: ;stop internal 80C515A baudrate generator
        CLR  BD
        MOV  SRELH,#3
        MOV  SRELL,#0D9H
        ANL  PCON,#07FH
        RET

        ENDIF


        IFDEF DS80C320
        ;Dallas 80C320 timer 1 with clock/12 or clock/4 prescaler

        CKCON   DATA 08EH

INITBG: ;start 80C320 baudrate generator timer 1
        MOV  CKCON,#PRESCALE
        MOV  TCON,#0
        MOV  TMOD,#020H
        MOV  TH1,#RELOAD
        ANL  PCON,#07FH
        ORL  PCON,#SMOD
        SETB TR1
        RET

STOPBG: ;stop 80C320 baudrate generator timer 1
        CLR  A
        MOV  TCON,A
        MOV  TMOD,A
        MOV  TH1,A
        MOV  TL1,A
        ANL  PCON,#07FH
        MOV  CKCON,#1
        RET

        ENDIF

        END