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16c1731e54
AppleIIAsm-Collection/disks/disk3_math/T.MATH16.LIB
nathanriggs 16c1731e54 Strings 0.2.0 update 
- bugfixes
- implemented required library
- commenting updates
- .min of every routine
2018-12-22 20:35:05 -05:00

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*-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=*
* *
* MATH.LIB *
* *
* AUTHOR: NATHAN RIGGS *
* CONTACT: NATHAN.RIGGS@ *
* OUTLOOK.COM *
* *
* VERSION: 0.2.0 *
* DATE: 12-DEC-2018 *
* ASSEMBLER: MERLIN 8 PRO *
* OS: DOS 3.3 *
* LICENSE: APACHE 2.0 *
* *
* STANDARD INTEGER MATH *
* LIBRARY FOR 16-BIT VALUES, *
* SIGNED OR UNSIGNED, AS WELL *
* AS 16-BIT PRNG ROUTINES. *
* *
*------------------------------*
* *
* LIST OF ROUTINES *
* *
* ADDIT16: 16-BIT ADD *
* SUBT16: 16BIT SUBTRACT *
* MULT16 : 16BIT MULTIPLY *
* SDIVD16: 16BIT DIVIDE (SIGN) *
* UDIVD16: 16BIT DIVIDE (UNSN) *
* SREMD16: 16BIT REMNDR (SIGN) *
* UREMD16: 16BIT REMNDR (UNSN) *
* COMP16 : 16BIT COMPARE *
* RAND16 : RANDOM # 0..65535 *
* *
*-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=*
*
*``````````````````````````````*
* ADDIT16 :: ADD 16-BIT VALUES *
*- -*
* ADDS TWO SIXTEEN BIT VALUES *
* AND RETURNS A 16 BIT VALUE *
* IN .Y (LOW) AND .X (HIGH). *
* CAN BE SIGNED OR UNSIGNED. *
*- -*
* CLOBBERS: *
* *
* FLAGS: ????---- REG: AXYM *
*- -*
* CYCLES: ??? *
* SIZE: *
*- -*
* USAGE: *
* *
* LDA #>1000 *
* PHA *
* LDA #<1000 *
* PHA *
* LDA #>1200 ; ADD2 *
* PHA *
* LDA #<1200 *
* PHA *
* JSR ADDIT16 *
*- -*
* ENTRY *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* ADDEND 2 LOW BYTE *
* ADDEND 2 HIGH BYTE *
* ADDEND 1 LOW BYTE *
* ADDEND 1 HIGH BYTE *
*- -*
* EXIT *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* *
* .Y = LOW BYTE OF RESULT *
* .X = HIGH BYTE OF RESULT *
* .A = LOW BYTE OF RET ADDR *
* *
* [RETURN] = RESULT (2 BYTES) *
* [RETLEN] = 2 (RESULT LENGTH) *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
ADDIT16
*
** GET RETURN ADDR
*
PLA
STA RETADR
PLA
STA RETADR+1
*
** GET PARAMETERS
*
PLA
STA :ADD2
PLA
STA :ADD2+1
PLA
STA :ADD1
PLA
STA :ADD1+1
*
LDA :ADD1
CLC
ADC :ADD2
TAY ; LOW BYTE
STY RETURN
LDA :ADD1+1
ADC :ADD2+1
TAX ; HIGH BYTE
STX RETURN+1
LDA #2
STA RETLEN
*
** RESTORE RETURN ADDRESS
*
LDA RETADR+1
PHA
LDA RETADR
PHA
*
RTS
*
** DATA
*
:ADD1 DS 2
:ADD2 DS 2
*
*``````````````````````````````*
* SUBT16 :: SUBTRACT WORDS *
*- -*
* SUBTRACT ONE 16BIT NUMBER *
* FROM ANOTHER, RETURNING THE *
* RESULT IN .Y (LOW), .X (HI). *
* SIGNED OR UNSIGNED. *
*- -*
* CLOBBERS: *
* *
* FLAGS: ????---- REG: AXYM *
*- -*
* CYCLES: ??? *
* SIZE: *
*- -*
* USAGE: *
* *
* LDA #>1000 ; MINUEND *
* PHA *
* LDA #<1000 *
* PHA *
* LDA #>500 ; SUBTRAHEND *
* PHA *
* LDA #<500 *
* PHA *
* JSR SUBT16 *
*- -*
* ENTRY *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* LOW BYTE OF SUBTRAHEND *
* HIGH BYTE OF SUBTRAHEND *
* LOW BYTE OF MINUEND *
* HIGH BYTE OF MINUEND *
*- -*
* EXIT *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* *
* .Y = RESULT LOW BYTE *
* .X = RESULT HIGH BYTE *
* .A = LOW BYTE OF RET ADDR *
* *
* [RETURN] = RESULT (2 BYTES) *
* [RETLEN] = 2 (RESULT LENGTH) *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
SUBT16
*
** GET RETURN ADDRESS
*
PLA
STA RETADR
PLA
STA RETADR+1
*
** GET PARAMETERS
*
PLA
STA :SUBT
PLA
STA :SUBT+1 ; SUBTRAHEND
PLA
STA :MINU
PLA
STA :MINU+1 ; MINUEND
*
** MINUEND - SUBTRAHEND
*
LDA :MINU
SEC
SBC :SUBT
TAY ; LOW BYTE
STY RETURN
LDA :MINU+1
SBC :SUBT+1
TAX ; HIGH BYTE
STX RETURN+1
LDA #2
STA RETLEN
*
** RESTORE RETURN ADDRESS
*
LDA RETADR+1
PHA
LDA RETADR
PHA
*
RTS
*
** DATA
*
:MINU DS 2
:SUBT DS 2
*
*``````````````````````````````*
* MULT16 :: MULTIPLY WORDS *
*- -*
* PERFORM MULTIPLICATION USING *
* THE SHIFT AND ADD ALGORITHM *
* *
* NOTE: WHILE THIS DOES PASS *
* THE FULL 32BIT PRODUCT BACK *
* VIA X AND Y, THIS WOULD *
* RETURN FALSE RESULTS IF ONE *
* OF THE PARAMETERS HAD BEEN *
* SIGNED. THUS, USUALLY ONLY *
* THE LOW WORD IS USED. *
*- -*
* CLOBBERS: *
* *
* FLAGS: ????---- REG: AXYM *
*- -*
* CYCLES: ??? *
* SIZE: *
*- -*
* USAGE: *
* *
* LDA #>1000 *
* PHA *
* LDA #<1000 ; MCAND *
* PHA *
* LDA #>3 *
* PHA *
* LDA #<3 ; MLIER *
* PHA *
* JSR MUL16 ; = 3000 *
*- -*
* ENTRY *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* LOW BYTE OF MULTIPLIER *
* HIGH BYTE OF MULTIPLIER *
* LOW BYTE OF MULTIPLICAND *
* HIGH BYTE OF MULTIPLICAND *
*- -*
* EXIT *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* LOW BYTE OF PRODUCT *
* HIGH BYTE OF PRODUCT (16BIT) *
* *
* .Y = LOW BYTE OF HIGH WORD *
* .X = HIGH BYTE OF HIGH WORD *
* .A = LOW BYTE OF RET ADDR *
* *
* [RETURN] = RESULT (2 BYTES) *
* [RETLEN] = 2 (RESULT LENGTH) *
*- -*
* ADAPTED FROM LEVANTHAL AND *
* WINTHROP'S /6502 ASSEMBLY *
* LANGUAGE ROUTINES/. *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
MULT16
*
** GET RETURN ADDRESS
*
PLA
STA RETADR
PLA
STA RETADR+1
*
** GET PARAMETERS
*
PLA
STA :MLIER
PLA
STA :MLIER+1
PLA
STA :MCAND
PLA
STA :MCAND+1
*
** PERFORM MULTIPLICATION USING THE SHIFT
** AND ADD ALGORITHM, WHICH PRODUCES AN
** UNSIGNED 32-BIT PRODUCT IN :HIPROD AND
** :MLIER WITH :HIPROD BEING THE HIGH WORD.
*
LDA #0
STA :HPROD ; ZERO HIGH WORD
STA :HPROD+1
LDX #17 ; # OF BITS IN MPLIER
; PLUS 1. EXTRA LOOP IS
; TO MOVE LAST CARRY INTO
; THE PRODUCT.
CLC ; CLEAR CARRY FOR 1ST TIME
; THROUGH LOOP.
:MULLP
*
** IF NEXT BIT = 1 THEN
** HIPROD = HIPROD+MCAND
*
ROR :HPROD+1
ROR :HPROD
ROR :MLIER+1
ROR :MLIER
BCC :DECCNT ; BR IF NEXT BIT OF
; MULTIPLIER IS 0
CLC ; NEXT BIT=1 SO ADD MCAND
; TO PRODUCT
LDA :MCAND
ADC :HPROD
STA :HPROD
LDA :MCAND+1
ADC :HPROD+1
STA :HPROD+1 ; CARRY = OVERFLOW
; FROM ADD
:DECCNT
DEX
BNE :MULLP ; CONTINUE UNTIL DONE
LDY :HPROD ; LOW BYTE OF HIGH WORD
LDX :HPROD+1 ; HIGH BYTE OF HIGH WORD
*
** PUSH LOW WORD OF PRODUCT ONTO THE STACK
*
LDA :MLIER+1
TAX
STX RETURN+1
LDA :MLIER
TAY
STY RETURN
LDA :HPROD
STA RETURN+2
LDA #2
STA RETLEN
*
** RESTORE RETURN ADDRESS
*
LDA RETADR+1
PHA
LDA RETADR
PHA
*
LDA :HPROD ;24BIT
RTS
*
** DATA
*
:MCAND DS 3
:MLIER DS 3
:HPROD DS 2
*
*``````````````````````````````*
* 16-BIT DIVISION: *
* *
* SDIV16, UDIV16, SREM16, AND *
* UREM16. *
*- -*
* SDIV16: DIVIDED 2 SIGNED BIT *
* WORDS AND RETURN A 16-BIT *
* SIGNED QUOTIENT. *
* *
* UDIV16: DIVIDE 2 UNSIGNED *
* 16BIT WORDS AND RETURN A *
* 16BIT UNSIGNED QUOTIENT. *
* *
* SREM16: DIVIDE 2 SIGNED *
* 16BIT WORDS AND RETURN A *
* 16BIT SIGNED REMAINDER. *
* *
* UREM16: DIVIDE 2 UNSIGNED *
* 16BIT WORKDS AND RETURN A *
* 16BIT UNSIGNED REMAINDER. *
*- -*
* CLOBBERS: *
* *
* FLAGS: ????---- REG: AXYM *
*- -*
* CYCLES: ??? *
* SIZE: *
*- -*
* USAGE: *
* *
** ALL ROUTINES USE THE SAME *
** FORMAT. *
* *
* LDA #>10000 *
* PHA *
* LDA #<10000 ; DIVIDEND *
* PHA *
* LDA #>1000 ; DIVISOR *
* PHA *
* LDA #<1000 *
* PHA *
* JSR UDIV16 *
*- -*
* ENTRY *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* LOW BYTE OF DIVISOR *
* HIGH BYTE OF DIVISOR *
* LOW BYTE OF DIVIDEND *
* HIGH BYTE OF DIVIDEND *
*- -*
* EXIT *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* *
* IF NO ERRORS, CARRY = 0, *
* ELSE CARRY=1, QUOTIENT=0, *
* AND REMAINDER=0 *
* *
* .Y = COUNTER; TRASH *
* .X = COUNTER; TRASH *
* .A = LOW BYTE OF RET ADDR *
* *
* [RETURN] = RESULT (2 BYTES) *
* [RETLEN] = 2 (RESULT LENGTH) *
*- -*
* ADAPTED FROM LEVANTHAL AND *
* WINTHROP'S /6502 ASSEMBLY *
* LANGUAGE ROUTINES/. *
* AS SUCH, IT MAY FALL UNDER A *
* DIFFERENT LICENSE UNTIL IT *
* IS RADICALLY REWORKED. *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
UDIVD16
LDA #0
BEQ UDIVMD
UREMD16
LDA #2
UDIVMD
STA _RSLTI
*
** GET RETURN ADDRESS
*
PLA
STA RETADR
PLA
STA RETADR+1
*
** GET PARAMETERS
*
PLA
STA _DVSOR
PLA
STA _DVSOR+1
PLA
STA _DVEND
PLA
STA _DVEND+1
*
JSR UDIV
BCC DIVOK ; BR IF NO ERR
DIVERR JMP EREXIT
DIVOK JMP OKEXIT
*
** SIGNED DIVISION
*
SDIVD16
LDA #0 ; RESULT IS QUOTIENT
BEQ SDIVMD ; (INDEX=0)
*
** SIGNED REMAINDER
*
SREMD16
LDA #2 ; RES = REMAINDER (I=2)
BNE SDIVMD
*
SDIVMD
STA _RSLTI ;RESULT INDEX;0=Q,2=R
*
** GET RETURN ADDRESS
*
PLA
STA RETADR
PLA
STA RETADR+1
*
** GET PARAMETERS
*
PLA
STA _DVSOR
PLA
STA _DVSOR+1
PLA
STA _DVEND
PLA
STA _DVEND+1
*
*
** DETERMINE SIGN OF QUOTIENT BY
** PERFORMING AN EXCLUSIVE OR OF
** THE HIGH BYTES. IF THE SIGNS
** ARE THE SAME THEN BIT 7 WILL
** BE 0 AND THE QUOTIENT IS
** POSITIVE. IF THE SIGNS ARE
** DIFFERENT THEN THE QUOTIENT
** IS NEGATIVE.
*
LDA _DVEND+1
EOR _DVSOR+1
STA _SQUOT
*
** SIGN OF REMAINDER IS THE SIGN
** OF THE DIVIDEND
*
LDA _DVEND+1
STA _SREMD
*
** TAKE THE ABSOLUTE VALUE OF
** THE DIVISOR
*
LDA _DVSOR+1
BPL CHKDE ; BR IF ALREADY POS
LDA #0 ; SUB DVSOR FROM ZERO
SEC
SBC _DVSOR
STA _DVSOR
LDA #0
SBC _DVSOR+1
STA _DVSOR+1
*
** TAKE ABS VALUE OF THE DIVIDEND
*
CHKDE
LDA _DVEND+1
BPL DODIV ; BR IF DVEND IS POS
LDA #0 ; SUB DVEND FROM ZERO
SEC
SBC _DVEND
STA _DVEND
LDA #0
SBC _DVEND+1
STA _DVEND+1
*
** DIVIDE ABS VALUES
*
DODIV
JSR UDIV
BCS EREXIT ; EXIT IF DIV BY 0
*
** NEGATE QUOTIENT IF IT IS NEGATIVE
*
LDA _SQUOT
BPL DOREM ; BR IF Q IS POS
LDA #0
SEC
SBC _DVEND
STA _DVEND
LDA #0
SBC _DVEND+1
STA _DVEND+1
*
DOREM
*
** NEGATE REMAINDER IF IT IS NEG
*
LDA _SREMD
BPL OKEXIT ; BR IF REM IS POS
LDA #0
SEC
SBC _DVEND+2
STA _DVEND+2
LDA #0
SBC _DVEND+3
STA _DVEND+3
JMP OKEXIT
*
** ERROR EXIT (CARRY=1, RSLTS ARE 0)
*
EREXIT
LDA #0
STA _DVEND
STA _DVEND+1 ;QUOTIENT = 0
STA _DVEND+2
STA _DVEND+3 ; REMAINDER=0
STA RETURN
STA RETURN+1
LDA #2
STA RETLEN
SEC ; CARRY=1 IF ERROR
BCS DVEXIT
*
** GOOD EXIT (CARRY = 0)
*
OKEXIT
CLC ; CARRY = 0, NO ERRORS
*
DVEXIT
*
** STORE RESULT
*
LDX _RSLTI ;GET INDEX TO RESULT
; 0=QUOTIENT, 2=REMAINDER
*
** STORE RESULT
*
LDA _DVEND,X
TAY
LDA _DVEND+1,X
TAX
STY RETURN
STX RETURN+1
LDA #2
STA RETLEN
*
** RESTORE RETURN ADDRESS
*
LDA RETADR+1
PHA
LDA RETADR
PHA
*
RTS
*
********************************
* UDIV ROUTINE
********************************
UDIV
*
** ZERO UPPER WORD DIVIDEND
** THIS WILL BE CALLED
** DIVIDEND(1) BELOW
*
LDA #0
STA _DVEND+2
STA _DVEND+3
*
** FIRST CHECK FOR DIV BY 0
*
LDA _DVSOR
ORA _DVSOR+1
BNE OKUDIV ; BR IF DVSOR NOT 0
SEC
RTS
*
** PERFORM THE DIVISION BY
** TRIAL SUBTRACTIONS
*
OKUDIV
LDX #16 ; LOOP THROUGH 16 BITS
DIVLP
ROL _DVEND ;SHFT CARRY INTO BIT 0 OF DVEND
ROL _DVEND+1 ;WHICH WILL BE THE QUOTIENT AND
ROL _DVEND+2 ;SHFT DVEND AT THE SAME TIME
ROL _DVEND+3
CHKLT
SEC
LDA _DVEND+2
SBC _DVSOR
TAY ; SAVE LOW BYTE IN Y
LDA _DVEND+3
SBC _DVSOR+1 ;SUB HIGHBYTES W RES IN A
BCC DECCNT ; BR IF DVEND < DVSOR AND CARRY
STY _DVEND+2 ; ELSE
STA _DVEND+3 ;VEN(1)=DVEND(1)-DVSOR
*
DECCNT
DEX
BNE DIVLP
*
ROL _DVEND ;SHFT IN LAST CAR FOR QUOT
ROL _DVEND+1
CLC ; NO ERRORS, CLEAR CARRY
RTS
*
** DATA
*
_DVSOR DS 2 ; DIVISOR
_DVEND DS 4 ; DIVIDEND[0] AND QUOTIENT
; DIVIDEND[1] AND REMAINDER
_SQUOT DS 1 ; SIGN OF QUOTIENT
_SREMD DS 1 ; SIGN OF REMAINDER
_RSLTI DS 1 ; RESULT INDEX
*
*``````````````````````````````*
* COMP16 :: 16-BIT COMPARE *
*- -*
* COMPARE TWO 16BIT SIGNED OR *
* UNSIGNED WORDS AND RETURN *
* THE C,Z,N FLAGS AS SET OR *
* CLEARED. *
*- -*
* CLOBBERS: *
* *
* FLAGS: CZN----- REG: AXYM *
*- -*
* CYCLES: ??? *
* SIZE: *
*- -*
* USAGE: *
* *
* LDA #>123 *
* PHA *
* LDA #<123 *
* PHA ; WORD 1 *
* LDA #>1023 *
* PHA *
* LDA #<1023 *
* PHA ; WORD 2 *
* JSR CMP16 *
*- -*
* ENTRY *
* *
* TOP OF STACK *
* *
* LOW BYTE OF RETURN ADDRESS *
* HI BYTE OF RETURN ADDRESS *
* LOW BYTE OF WORD 2 (SUBTRA) *
* HIGH BYTE OF WORD 2 *
* LOW BYTE OF WORD 1 (MINU) *
* HIGH BYTE OF WORD 1 *
*- -*
* EXIT *
* *
* TOP OF STACK *
* *
* FLAGS RETURNED BASED ON WORD *
* 1 - WORD 2. *
* *
* IF W1 & W2 ARE 2S COMPLEMENT *
* IF W1 = W2 Z=1,N=0 *
* IF W1 > W2 Z=0,N=0 *
* IF W1 < W2 Z=0,N=1 *
* ELSE *
* IF W1 = W2 Z=1,C=1 *
* IF W1 > W2 Z=0,C=1 *
* IF W1 < W2 Z=0,C=0 *
* *
*- -*
* ADAPTED FROM LEVANTHAL AND *
* WINTHROP'S /6502 ASSEMBLY *
* LANGUAGE ROUTINES/. *
* AS SUCH, THE SAME LICENSE *
* MAY NOT APPLY UNTIL RADICAL *
* ALTERATION. *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
COMP16
*
** GET RETURN ADDRESS
*
PLA
STA RETADR
PLA
STA RETADR+1
*
** GET PARAMETERS
*
PLA
STA :SUBT ; SUBTRAHEND
PLA
STA :SUBT+1
PLA
STA :MINU ; MINUEND
PLA
STA :MINU+1
*
** RESTORE RETURN ADDRESS
*
LDA RETADR+1
PHA
LDA RETADR
PHA
*
LDA :MINU
CMP :SUBT ; COMPARE LOW BYTES
BEQ :EQUAL
*
** LOW BYTES ARE NOTE EQUAL
** COMPARE HIGH BYTES
*
LDA :MINU+1
SBC :SUBT+1 ; COMPARE HIGH BYTES
ORA #1 ; MAKE Z=0, SINCE LOW
; BYTES ARE NOT EQUAL
BVS :OVFLOW ; MUST HANDLE OVERFLOW
; FOR SIGNED MATH
RTS ; EXIT
*
** LOW BYTES ARE UQAL -- COMPARE HIGH
*
:EQUAL
LDA :MINU+1
SBC :SUBT+1 ; UPPER BYTES
BVS :OVFLOW
RTS ; RETURN W FLAGS SET
*
**
** OVERFLOW WITH SIGNED ARITHMETIC SO
** COMPLEMENT THE NEGATIVE FLAG.
** DO NO CHANGE THE CARRY FLAG AND
** MAKE THE ZERO FLAG EQUAL TO 0.
** COMPLEMENT NEG FLAG BY EORING
** #$80 AND ACCUMULATOR.
**
*
:OVFLOW
EOR #$80 ; COMPLEMENT N FLAG
ORA #1 ; IF OVERFLOW THEN THE
; WORDS ARE !=. Z= 0
; CARRY UNCHANGED
RTS
*
** DATA
*
:MINU DS 2
:SUBT DS 2
*
*``````````````````````````````*
* RAND16 : 16BIT RANDOM NUMBER *
*- -*
* GENERATE A 16BIT PSEUDO- *
* RANDOM NUMBER AND RETURN IT *
* IN Y,X (LOW, HIGH). *
* *
* ORIGINAL AUTHOR IS WHITE *
* FLAME, AS SHARED ON *
* CODEBASE64. *
*- -*
* CLOBBERS: *
* *
* FLAGS: ????---- REG: AXYM *
*- -*
* CYCLES: ??? *
* SIZE: *
*- -*
* USAGE: *
* *
*- -*
* ENTRY *
* *
* LOW BYTE OF RETURN ADDRESS *
* HIGH BYTE OF RETURN ADDRESS *
*- -*
* EXIT *
* *
* .Y = HIGH BYTE OF PRODUCT *
* .X = LOW BYTE OF PRODUCT *
* .A = LOW BYTE OF PRODUCT *
* *
* [RETURN] = RESULT (2 BYTES) *
* [RETLEN] = 2 (RESULT LENGTH) *
*- -*
* NOTE: THERE ARE 2048 MAGIC *
* NUMBERS THAT COULD BE EOR'D *
* TO GENERATE A PSEUDO-RANDOM *
* PATTERN THAT DOESN'T REPEAT *
* UNTIL 65535 ITERATIONS. TOO *
* MANY TO LIST HERE, BUT SOME *
* ARE: $002D, $1979, $1B47, *
* $41BB, $3D91, $B5E9, $FFEB *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
RAND16
*
LDA RNDL
STA :SEED
LDA RNDH
STA :SEED+1
*
LDA :SEED
BEQ :LOW0
*
** DO A NORMAL SHIFT
*
ASL :SEED
LDA :SEED+1
ROL
BCC :NOEOR
:DOEOR ; HIGH BYTE IN A
EOR #>$0369
STA :SEED+1
LDA :SEED
EOR #<$0369
STA :SEED
JMP :EXIT
:LOW0
LDA :SEED+1
BEQ :DOEOR
ASL
BEQ :NOEOR
BCS :DOEOR
:NOEOR
STA :SEED+1
:EXIT LDX :SEED+1
LDY :SEED
STY RETURN
STX RETURN+1
LDA #2
STA RETLEN
RTS
*
** DATA
*
:SEED DS 2
*
*``````````````````````````````*
* RANDW :: RANDOM WORD *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
*
** THIS WILL BE INCLUDED IN FUTURE UPDATES
*
*
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