ORG 0000H
Reference address：Use right shift addition to perform multiplication (65535*65535)
JMP A1
ORG 002BH
ORG 002BH
A1: MOV R0,#0; data processing register high bit (product high 8 bits)
MOV R1,#0; data processing register low bit (product high 8 bits)
MOV R1,#0; data processing register low bit (product high 8 bits)
MOV R2, #255; High bit of multiplicand (low middle 8 bits of product)
MOV R3, #255; Low bit of multiplicand (low 8 bits of product)
MOV R3, #255; Low bit of multiplicand (low 8 bits of product)
MOV R4, #255; Multiplier high
MOV R5, #255; Multiplier low
MOV R5, #255; Multiplier low
MOV 30H,#16;Number of loops--8-bit binary number multiplied 8 times 4-bit is 4 times
A2:
CLR C; Clear C
MOV A,R3;
JNB ACC.0,A3; Determine whether the 0th bit of the multiplicand is 0, if yes, no need to add
A2:
CLR C; Clear C
MOV A,R3;
JNB ACC.0,A3; Determine whether the 0th bit of the multiplicand is 0, if yes, no need to add
MOV A, R1; if not 0, add
ADD A, R5; add the low bit of the multiplier to the low bit of the processed data
MOV R1, A; store the data back to the low bit register of the data processing
ADD A, R5; add the low bit of the multiplier to the low bit of the processed data
MOV R1, A; store the data back to the low bit register of the data processing
MOV A, R0
ADDC A, R4; add the low bit of the multiplier to the high bit of the processed data. The addition may overflow, so use ADDC
MOV R0, A; store the data back to the high bit register of the data processing
ADDC A, R4; add the low bit of the multiplier to the high bit of the processed data. The addition may overflow, so use ADDC
MOV R0, A; store the data back to the high bit register of the data processing
A3: MOV A, R0; first right shift the high bit
RRC A; the addition may overflow so use RRC
MOV R0, A;
RRC A; the addition may overflow so use RRC
MOV R0, A;
MOV A, R1; shift the low bit right
RRC A; RRC moves the high bit to the low bit
MOV R1, A
RRC A; RRC moves the high bit to the low bit
MOV R1, A
MOV A, R2;
RRC A; Move the processed number to the high position of the multiplicand
MOV R2, A;
RRC A; Move the processed number to the high position of the multiplicand
MOV R2, A;
MOV A,R3;
RRC A; Move the processed number to the low position of the multiplicand
MOV R3,A;
DJNZ 30H,A2; Is it completed?
NOP
NOP
NOP
JMP $
RRC A; Move the processed number to the low position of the multiplicand
MOV R3,A;
DJNZ 30H,A2; Is it completed?
NOP
NOP
NOP
JMP $
END
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Algorithm Design (Jon Kleinberg Éva Tardos)
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