sum_of_negative_and_positive_integers.asm

用汇编写成的将正负数分别相加

				ORG 10000H
BLOCK 		EQU 40H
LEN			EQU 20H
PSUM			EQU 11H
MSUM			EQU 13H
				SJMP INI;jamp to initialize data block
;plus positive and negative respectively
START:		MOV R7,#LEN;R7 is the number of loops
				MOV R0,#BLOCK;
				CLR PSUM
				CLR MSUM
LOOP:			MOV A,@R0;move one of data block to A
				INC R0;make R0 point to the next data address of data block
				CLR C
				JB ACC.7,MADD;if A is negative
				ADD A,PSUM;if A is positive, plus PSUM to A
				MOV PSUM,A;move A to PSUM
				MOV A,PSUM-1;move the higher bit of PSUM to A
				ADDC A,#0;care of carry
				MOV PSUM-1,A
				SJMP NEXT;
MADD:			ADD A,MSUM;do as same as before
				MOV MSUM,A
				MOV A,#0FFH;adjust the value
				ADDC A,MSUM-1
				MOV MSUM-1,A
NEXT:			DJNZ R7,LOOP;not at the end of data block,go into next loop
				SJMP FINISH

INI:			MOV R0,#BLOCK
				MOV R7,#LEN
				MOV R1,#7H;adjust value
LOOP1:		MOV A,R1
				MOVC A,@A+PC;get value
				MOV @R0,A;1 bit save value to data block
				INC R0;1 bit; make R0 point to the next data address of data block
				INC R1;1 bit; change the adjusting value
NEXT1:		DJNZ R7,LOOP1;2 bits; not at the end of the data block,continue
				SJMP START;2 bit; having initialized data block,go to deal with them

DATATAB:		DB 00,01,02,03,04,05,06,07
				DB 78h,79h,7ah,7bh,7ch,7dh,7eh,7fh
				DB 80h,81h,82h,83h, 84h, 85h,86h,87h
				DB 0f8h,0f9h,0fah,0fbh,0fch,0fdh,0feh,0ffh
FINISH:		SJMP $
				END