8051汇编查表程序

debug_trig MACRO
CPL P1_0
ENDM

//宏定义PID采样值，NZRI编码之后，LSB
PID_ACK    EQU   02h
PID_SETUP  EQU   08h
PID_OUT    EQU   0Ah
PID_IN     EQU   0Bh
PID_DATA1  EQU   0Ch
PID_DATA0  EQU   0Dh

SAMPLE_PIN  BIT   P0_0



// r0里面存正在接收的数据， r7为接收数据长度, r6为接收buffer指针, r5采样总线
CSEG    AT    00003H
    sjmp   pid_sample

PID_TABLE:  DB   \
                PID_SETUP, LOW(setup_preprocess),   HIGH(setup_preprocess),      \
                PID_DATA0, LOW(data0_preprocess),   HIGH(data0_preprocess),     \
                PID_DATA1, LOW(data_process),       HIGH(data_process),     \
                PID_IN,    LOW(in_process),         HIGH(in_process),       \
                PID_ACK,   LOW(ack_process),        HIGH(ack_process),       \
                PID_OUT,   LOW(out_procsee),        HIGH(out_procsee)


ack_process:

    ret    

    
setup_preprocess:
    ret

out_procsee:
    ret

in_process:
    ret

data_process:
    ret

data0_preprocess:
    mov     r2, #08h   //采集Byte数，采集8byte标准请求
    mov     r1, #07h   //每个byte采样次数 setup采7次
    nop


pid_sample:
    mov   a, r0           //数据暂存到A
    debug_trig
    mov   c, SAMPLE_PIN       //采样总线
    rlc   a               //数据位右移
    mov   r0, a    
    djnz  r1, pid_sample   
get_pid_process_start:
    mov DPTR, #PID_TABLE
check_pid:
    clr a
    MOVC A, @A+DPTR
    xrl  a, r0
    jnz  next_pid  //如果PID不匹配，取下一个比较
    inc  DPTR
    MOVC A, @A+DPTR
    mov r0, a
    inc  DPTR
    clr  a
    MOVC A, @A+DPTR
    mov DPH, a
    mov DPL, r0

    CLR    A
    JMP    @A+DPTR
     
next_pid:          //此处有可能需要处理无法识别的PID
    inc DPTR
    inc DPTR
    inc DPTR
    sjmp check_pid

//不认识的PID类型
avlid_pid:
    sjmp avlid_pid