[旋风][6502汇编][16位除法]

;[Division][16_16_16]

;FlameCyclone 20181120

Dividend_L = $00 ;被除数低位

Dividend_H = Dividend_L + 1 ;被除数高位

Divisor_L = $02 ;除数低位

Divisor_H = Divisor_L + 1 ;除数高位

Quotient_L = $04 ;最终商低位

Quotient_H = Quotient_L + 1 ;最终商高位

Multiple_L = $06 ;位倍数低位

Multiple_H = $07 ;位倍数高位

;65535/1耗时1562

;65535/255耗时467

;65535/65535耗时120

;Division

 .ORG $8000

 

 LDA #255

 STA Dividend_L

 LDA #255

 STA Dividend_H

 LDA #255

 STA Divisor_L

 LDA #255

 STA Divisor_H

 JSR Division

 RTS

Division: ;除法计算

 LDA #$01

 STA Multiple_L

 LDX #$00

 STX Multiple_H

 STX Quotient_L

 STX Quotient_H

 

 LDA Divisor_L

 BNE Multiple_Set

 LDA Divisor_H

 BEQ Division_End

Multiple_Set:

 LDA Divisor_H

 BMI Compare

 BNE Align_Bits

 LDA Divisor_L

 STA Divisor_H

 STX Divisor_L

 STX Multiple_L

 INC Multiple_H

 LDX #$08

 LDA Divisor_H

 BMI Compare

Align_Bits: ;被除数与除数左端对齐

 INX

 ASL Multiple_L

 ROL Multiple_H

 ASL Divisor_L

 ROL Divisor_H

 BPL Align_Bits

Compare: ;被除数与除数比较

 LDA Dividend_H

 CMP Divisor_H

 BCC MoveBits_Right

 BNE Subtraction_L1

 LDA Dividend_L

 CMP Divisor_L

 BCS Subtraction

MoveBits_Right:

 LSR Divisor_H

 ROR Divisor_L

 LSR Multiple_H

 ROR Multiple_L

 JMP Compare

 

Subtraction: ;被除数-除数

 LDA Dividend_H

Subtraction_L1:

 SBC Divisor_H

 STA Dividend_H

 LDA Dividend_L

 SBC Divisor_L

 STA Dividend_L

Accumulation:

 LDA Quotient_L ;商 = 商 | 位倍数

 ORA Multiple_L

 STA Quotient_L

 LDA Quotient_H

 ORA Multiple_H

 STA Quotient_H

 DEX

 BMI Division_End

 LDA Dividend_L

 BNE MoveBits_Right

 LDA Dividend_H

 BNE MoveBits_Right

Division_End: ;乘法计算结束

 RTS