127 lines
2.9 KiB
ArmAsm
Executable File
127 lines
2.9 KiB
ArmAsm
Executable File
********************************
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* Mathematical routines used *
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* by Jewel of Kaldun *
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********************************
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********************************
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* Integer division routine. *
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* NUM0 = routine scratch *
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* space *
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* NUM1 = numerator *
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* NUM2 = denominator *
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* RESULT = quotient *
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* remainder is in NUM1 after *
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* completion of division. *
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********************************
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IDIV LDA #0
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STA RESULT
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STA RESULT+1
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LDA NUM2
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ORA NUM2+1
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BNE :PREP
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SEC
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RTS
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:PREP LDX #0
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LDA NUM2
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STA NUM0
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LDA NUM2+1
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STA NUM0+1
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:99 ASL NUM0
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ROL NUM0+1
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BCS :GO
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INX
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JMP :99
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:GO LDA NUM2
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STA NUM0
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LDA NUM2+1
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STA NUM0+1
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TXA
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TAY
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BEQ :SKIP
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:0 ASL NUM0
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ROL NUM0+1
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DEY
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BNE :0
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:SKIP LDA NUM0+1
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CMP NUM1+1
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BEQ :1
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BGE :CONT
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BLT :2
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:1 LDA NUM0
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CMP NUM1
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BEQ :2
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BGE :CONT
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:2 SEC
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LDA NUM1
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SBC NUM0
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STA NUM1
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LDA NUM1+1
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SBC NUM0+1
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STA NUM1+1
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LDA #0
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STA NUM0+1
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LDA #1
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STA NUM0
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TXA
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TAY
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BEQ :11
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:10 ASL NUM0
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ROL NUM0+1
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DEY
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BNE :10
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:11 CLC
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LDA RESULT
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ADC NUM0
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STA RESULT
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LDA RESULT+1
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ADC NUM0+1
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STA RESULT+1
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:CONT DEX
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BPL :GO
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CLC
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RTS
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********************************
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* Integer multiplication *
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* routine: *
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* NUM1 = one number *
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* NUM2 = second number *
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* RESULT = answer to NUM1xNUM2 *
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********************************
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IMUL LDA #0
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STA RESULT
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STA RESULT+1
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:MORE LDA NUM2
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BNE :GO
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LDA NUM2+1
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BNE :GO
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RTS
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:GO LSR NUM2+1
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ROR NUM2
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BCC :SHIFT
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CLC
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LDA NUM1
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ADC RESULT
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STA RESULT
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LDA NUM1+1
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ADC RESULT+1
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STA RESULT+1
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:SHIFT ASL NUM1
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ROL NUM1+1
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JMP :MORE
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********************************
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* Variables used by the *
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* integer multiplication and *
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* division routines: *
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********************************
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NUM0 HEX 0000
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NUM1 HEX 0000
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NUM2 HEX 0000
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RESULT HEX 0000
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