; C02 library stdlib.h02 assembly language subroutines ; Requires ; external zero page locations SRCLO and SRCHI ; and external locations RANDOM, RDSEED, TEMP0, TEMP1, and TEMP2. ;iabs(n) - Get Integer ABSolute Value ;Args: Y,X = Integer to get Absolute Value Of ;Sets: TEMP1, TEMP2 ;Affects: C, N, Z ;Returns: A = Absolute Value of Argument IABS: CPY #$80 ;If Negative (High Bit Set) BCC IABSX ; Carry will Already be Set JSR SAVRXY ; Copy LSB, MSB to TEMP1. TEMP2 LDA #0 ; Subtract LSB SBC TEMP1 ; from 0 TAX ; and Copy to X Register LDA #0 ; Subtract MSB SBC TEMP2 ; from 0 TAY ; and Copy to Y Register IABSX: RTS ;imax(i) - Get MAXimum of Two Integers ;Args: Y,X = Second Integer ;Uses: SRCHI,SRCLO = First Integer ;Affects: N,Z,C ;Returns: Y,X = Larger of the Two Arguments IMAX: CPY SRCHI ;If Y < SRCHI BCC IMAXC ; Return SRCLO, SRCHI CPX SRCLO ;IF X >= SRCLO BCS IMINX ; Return Argument IMAXC: JMP GETSRC ;Return Integer in SRCLO, SRCHI ;imin(i) - Get MINimum of Two Integers ;Args: Y,X = Second Integer ;Uses: SRCHI,SRCLO = First Integer ;Affects: N,Z,C ;Returns: Y,X = Larger of the Two Arguments IMIN: CPY SRCHI ;If Y < SRCHI BCC IMINX ; Return Argument BNE IMAXC ;If Y > SRCHI Return SRCHI,SRCLO CPX SRCLO ;If X >= SRCLO BCS IMAXC ; Return SRCHI,SRCLO IMINX: RTS ;Return Argument ;iaddc(c,i) - Add Byte c to Integer i IADDC: JSR SETSRC ;Save Integer and Clear Y TAX ;Copy Byte to LSB and drop into IADD ;iadd(d) - ADD Integer d to from Integer g ;Args: Y,X = Addend ;Requires: setsrc(g) - Augend ;Sets: TEMP1,TEMP2 = Addend ;Affects: Z,C ;Returns: A = Sum (Bits 16-23) ; Y,X = Sum (Bits 0-15) ; N = Sign of Result IADD: CLC ;Clear Carry for Addition TXA ;Add Addend LSB ADC SRCLO ;to Augend LSB TAX ;and Copy to X TYA ;Add Addend MSB ADC SRCHI ;to Augebd MSB TAY ;and Copy to Y LDA #0 ;Set Overflow to 0 ROL ; Rotate Carry (Same as Adding it) RTS ; and Return ;isub(s) - SUBtract Integer s from Integer m ;Args: Y,X = Subtrahend ;Requires: setsrc(m) - Minuend ;Sets: TEMP1,TEMP2 = Subtrahend ;Affects: Z,C ;Returns: A = Differencee (Bits 16-23) ; Y,X = Difference (Bits 0-15) ; N = Sign of Result ISUB: JSR SAVRXY ;Store Subtrahend in TEMP1,TEMP2 SEC ;Set Carry for Subtraction LDA SRCLO ;Load Minuend LSB SBC TEMP1 ;Subtract Subtrahend LSB TAX ;Copy Difference LSB to X LDA SRCHI ;Load Minuend MSB SBC TEMP2 ;Subtract Subtrahend MSB TAY ;Copy Difference MSB to Y LDA #0 ;Set Overflow Byte to 0 SBC #0 ; Subtract Carry RTS ; and Return ;imult(m) - MULTiply Two Integers ;Args: Y,X - Multiplier ;Requires: DSTHI,DSTLO = Multiplicand ;Sets: TEMP0-TEMP3 = 32 Bit Product ;Destroys: SRCHI, SRCLO ;Affects: A,C,Z,N ;Returns: Y,X = 16 Bit Product IMULT: JSR SETSRC ;Save Multiplier STY TEMP2 ;Clear Upper Bits of Product STY TEMP3 LDX #16 ;Rotate Through 16 Bits IMULTS: LSR SRCHI ;Divide Multiplier by 2 ROR SRCLO BCC IMULTR ;If Shifted out Bit is 1 LDA TEMP2 ; Add Multiplicand CLC ; to Upper Half of Product ADC DSTLO STA TEMP2 LDA TEMP3 ADC DSTHI IMULTR: ROR ;Rotate Partial Product STA TEMP3 ROR TEMP2 ROR TEMP1 ROR TEMP0 DEX ;Decrement Counter BNE IMULTS ;and Process Next Bit LDX TEMP0 LDY TEMP1 ;Return Low 16 Bits of Product RTS ;idiv(d) - DIVide Two Numbers ;Args: Y,X - Divisor ;Requires: DSTHI,DSTLO = Dividend ;Sets: SRCHI,SRCLO = Divisor ; DSTHI,DSTLO = Quotient ; TEMP1,TEMP2 = Remainder ;Affects: A,C,Z,N ;Returns: Y,X = 16 Bit Quotient IDIV: JSR SETSRC ;Save Divisor STA TEMP1 STA TEMP2 LDX #16 ;repeat for each bit: ... IDIVL: ASL DSTLO ;dividend lb & hb*2, msb -> Carry ROL DSTHI ROL TEMP1 ;remainder lb & hb * 2 + msb from carry ROL TEMP2 LDA TEMP1 SEC SBC SRCLO ;substract divisor to see if it fits in TAY ;lb result -> Y, for we may need it later LDA TEMP2 SBC SRCHI BCC IDIVS ;if carry=0 then divisor didn't fit in yet STA TEMP2 ;else save substraction result as new remainder, STY TEMP1 INC DSTLO ;and INCrement result cause divisor fit in 1 times IDIVS: DEX BNE IDIVL RTS ;ishftl(n,i) - Shift Integer i to the Left n Bits ;Sets: TEMP1, TEMP2 = LSB, MSB of Result ;Affects: A,Y,N,Z,C ;Returns: Y,X = Shifted Integer ISHFTL: JSR SAVRXY ;Save X,Y in TEMP1,TEMP2 TAY ;Set Counter to Number of Bits ASL TEMP1 ;Shift LSB to Left ROL TEMP2 ;Rotate MSB to Left DEY ;Decrement Counter BNE ISHFTL ; and Loop if Not 0 BEQ ISHFTX ;Return Shifted Integer ;ishftr(n,i) - Shift Integer i to the Right n Bits ;Sets: TEMP1, TEMP2 = LSB, MSB of Result ;Affects: A,Y,N,Z,C ;Returns: Y,X = Shifted Integer ISHFTR: JSR SAVRXY ;Save X,Y in TEMP1,TEMP2 TAY ;Copy LSR TEMP1 ;Shift LSB to Right ROR TEMP2 ;Rotate MSB to Right DEY ;Decrement Counter BNE ISHFTR ; and Loop if Not 0 ISHFTX: JMP RESRXY ;Load Shifted Integer and Return ;atoi(&s) - ASCII string TO Integer ;Args: Y,X = Address of String to Convert ;Sets: TEMP1, TEMP2 = Integer Value ;Affects: TEMP0 ;Returns: A = Number of Digits ; Y,X = Integer Value ATOI: JSR SETSRC ;Initialize Source String STY TEMP1 ;Initialize Result STY TEMP2 ATOIL: LDA (SRCLO),Y ;Get Next Character CMP #$30 ;If Less Than '0' BCC ATOIX ; Exit CMP #$3A ;If Greater Than '9' BCS ATOIX ; Exit AND #$0F ;Convert to Binary Nybble STA TEMP0 ; and Save It LDA TEMP1 ;Load Result LDX TEMP2 ASL TEMP1 ;Multiply by 5 by ROL TEMP2 ASL TEMP1 ; Multiplying by 4 ROL TEMP2 CLC ; And Adding Itself ADC TEMP1 STA TEMP1 TXA ADC TEMP2 STA TEMP2 ASL TEMP1 ;Multiply that by 2 ROL TEMP2 LDA TEMP0 ;Get Saved Nybble CLC ;and Add to Result ADC TEMP1 ;Add Saved Nybble STA TEMP1 ; and Store Result LDA #0 ADC TEMP2 STA TEMP2 INY ;Increment Index BPL ATOIL ; and Loop ATOIX: TYA ;Return Number of Digits JMP RESRXY ;and Integer Value ;itoa(n) - Integer TO ASCII string ;Args: Y,X = Integer Value to Convert ;Uses: DSTHI,DSTLO = Destination String ;Returns: A,Y = Length of String ITOA: JSR CVIBCD ;Convert Integer to Packed BCD LDY #0 ;Initialize Index into String STY TEMP3 ITOAA: LDY #4 ;Set Initial Digit Number ITOAZ: JSR UPBCDI ;Unpack Digit Y BNE ITOAS ;If Zero DEY ; Decrement Digit Number BNE ITOAZ ; If Not Zero Loop BEQ ITOAS ; Else IDIVS Unpack ITOAL: JSR UPBCDI ;Unpack Digit #Y ITOAS: TAX ;Save Digit in X TYA ;Push Digit Number into Stack PHA TXA ;and Restore Digit LDY TEMP3 ;Get Index into String ORA #$30 ;Convert Digit to ASCII STA (DSTLO),Y ;and Store in String INC TEMP3 ;Increment Index into String PLA ;Pull Digit Number off Stack TAY DEY ;Decrement Digit Number BPL ITOAL ;Loop if >= Zero LDA #0 ;Terminate String STA (DSTLO),Y TYA ;Return String Length RTS ;upbcdi() - UnPack digits from BCD Integer ; Assumes that TEMP0, TEMP1, and TEMP2 ; are in consecutive memory locations ;Args: Y = Digit Number to Unpack (0-5) ;Uses: TEMP0 = Low Byte ; TEMP1 = Middle Byte ; TEMP2 = High Nybble ;Affects: X,C,N,Z ;Returns: A = Unpacked Digit UPBCDI: TYA ;Divide Digit Number by 2, LSR ; Setting Carry TAX ; if Digit Number is Odd LDA TEMP0,X ;Load BCD Byte BCC UPBCDS ;If Digit Number is Odd LSR ;Shift High Nybble to Low Nybble LSR LSR LSR UPBCDS: AND #$0F ;Strip Off High Nybble RTS ;cvibcd(int) - ConVert Integer to packed Binary Coded Decimal ;Args: Y,X - Integer to Convert ;Sets: TEMP0 = Tens and Ones Digit ; TEMP1 = Thousands and Hundreds Digit ; TEMP2 = Ten-Thousands Digit ;Affects: A,X,Y CVIBCD: LDA #0 ;Clear BCD Bytes STA TEMP0 STA TEMP1 STA TEMP2 PHP ;Save Status Register SEI ;Disable Interrupts SED ;Set Decimal Mode TYA ;Push MSB onto Stack PHA TXA ;Push LSB onto Stack PHA TSX ;Copy Stack Pointer to X LDY #16 ;Process 16 bits of Binary CVIBCL: ASL $101,X ;Shift High Bit Into Carry ROL $102,X LDA TEMP0 ;Add 6 Digit BCD Number Itself ADC TEMP0 ; Effectively Multiplying It by 2 STA TEMP0 ; and Adding in the Shifted Out Bit LDA TEMP1 ADC TEMP1 STA TEMP1 LDA TEMP2 ADC TEMP2 STA TEMP2 DEY ;Decrement Counter and BNE CVIBCL ; Process Next Bit PLA ;Restore Stack PLA PLP ;Restore Status Register RTS