帮详细点的分析下这个汇编程序执行步骤即每一部的作用

SSEG   SEGMENT  STACK      
STR    DB       100 DUP(0)
SSEG   ENDS
DSEG   SEGMENT
S      DW      ?                   ;unsinged short s;
DSEG   ENDS
CSEG       SEGMENT
           ASSUME  SS:SSEG,DS:DSEG
           ASSUME  CS:CSEG
START:   
           MOV  AX,SSEG
           MOV  SS,AX
           MOV  AX,DSEG
           MOV  DS,AX                  
           MOV  BX,1               ;unsigned short b = 1;
           MOV  AL,2               ;unsigned short a = 2;
LP:                                ;calculate bit2Npos                  
           MOV  AH,AL              ;a |= LOBYTE(a);
           MOV  CL,AL              ;unsigned char bit2Npos = LOBYTE(a);
           INC  AH              
           MUL  AH                 ;a = LOBYTE(a)*(HIBYTE(a)+1);
           ADD  BX,AX              ;b += a;   
           CMP  BX,126              
           JA   STOP               ;if (b > 200) goto stop               
           MOV  AL,CL
           INC  AL                 ;else a++;
           JMP  LP                 ;goto LP
STOP:     
           MOV  S,BX               ;s = b;   
           MOV  BL,CL              ;unsigned char para_b = bit2Npos;
           CALL DISP               ;disp(para_b);               
           MOV  AH,4CH            
           INT  21H                ;exit(0)
DISP       PROC                    ;void disp(unsigned char para_b);
           MOV DL,78
           MOV AH,02H
           INT 21H                 ;putchar('N');
           MOV DL,61
           MOV AH,02H
           INT 21H                 ;putchar('=')        
           MOV CH, 2               ;unsigned char i;         
L:     
           MOV CL, 4               ;unsigned char offset = 4;
           ROL BL, CL              ;#define ROL(x, s, n) ((x) >> (n)) | ((x) << ((s) - (n)))
           MOV DL, BL              ;unsigned char ch = para_b;      
           AND DL, 0FH             ;ch = (LOBYTE)ROL(para_b, 8, offset);   
           CMP DL, 10
           JB  NEXT                ;if (ch < 10) goto NEXT;
           ADD DL, 7               ;else ch += NUMERIC; #define NUMERIC (7)
NEXT:  
           ADD DL, 30H             ;ch += CHARACTER; #define CHARACTER (0x30)      
           MOV AH, 02H        
           INT 21H                 ;putchar(ch);
           DEC CH            
           JNZ L                   ;while(i--);
           RET                     ;return;
DISP       ENDP              
                          
CSEG       ENDS
END        START