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goapple2/source/redbook/fp.asm
Zellyn Hunter a32cd8bd12 Adding sources.
2014-05-13 08:10:55 -07:00

155 lines
8.1 KiB
NASM
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***********************
* *
* APPLE-II FLOATING *
* POINT ROUTINES *
* *
* COPYRIGHT 1977 BY *
* APPLE COMPUTER INC. *
* *
* ALL RIGHTS RESERVED *
* *
* S. WOZNIAK *
* *
***********************
TITLE "FLOATING POINT ROUTINES"
SIGN EPZ $F3
X2 EPZ $F4
M2 EPZ $F5
X1 EPZ $F8
M1 EPZ $F9
E EPZ $FC
OVLOC EQU $3F5
ORG $F425
F425: 18 ADD CLC CLEAR CARRY
F426: A2 02 LDX #$2 INDEX FOR 3-BYTE ADD.
F428: B5 F9 ADD1 LDA M1,X
F42A: 75 F5 ADC M2,X ADD A BYTE OF MANT2 TO MANT1
F42C: 95 F9 STA M1,X
F42E: CA DEX INDEX TO NEXT MORE SIGNIF. BYTE.
F42F: 10 F7 BPL ADD1 LOOP UNTIL DONE.
F431: 60 RTS RETURN
F432: 06 F3 MD1 ASL SIGN CLEAR LSB OF SIGN.
F434: 20 37 F4 JSR ABSWAP ABS VAL OF M1, THEN SWAP WITH M2
F437: 24 F9 ABSWAP BIT M1 MANT1 NEGATIVE?
F439: 10 05 BPL ABSWAP1 NO, SWAP WITH MANT2 AND RETURN.
F43B: 20 A4 F4 JSR FCOMPL YES, COMPLEMENT IT.
F43E: E6 F3 INC SIGN INCR SIGN, COMPLEMENTING LSB.
F440: 38 ABSWAP1 SEC SET CARRY FOR RETURN TO MUL/DIV.
F441: A2 04 SWAP LDX #$4 INDEX FOR 4 BYTE SWAP.
F443: 94 FB SWAP1 STY E-1,X
F445: B5 F7 LDA X1-1,X SWAP A BYTE OF EXP/MANT1 WITH
F447: B4 F3 LDY X2-1,X EXP/MANT2 AND LEAVE A COPY OF
F449: 94 F7 STY X1-1,X MANT1 IN E (3 BYTES). E+3 USED
F44B: 95 F3 STA X2-1,X
F44D: CA DEX ADVANCE INDEX TO NEXT BYTE
F44E: D0 F3 BNE SWAP1 LOOP UNTIL DONE.
F450: 60 RTS RETURN
F451: A9 8E FLOAT LDA #$8E INIT EXP1 TO 14,
F453: 85 F8 STA X1 THEN NORMALIZE TO FLOAT.
F455: A5 F9 NORM1 LDA M1 HIGH-ORDER MANT1 BYTE.
F457: C9 C0 CMP #$C0 UPPER TWO BITS UNEQUAL?
F459: 30 0C BMI RTS1 YES, RETURN WITH MANT1 NORMALIZED
F45B: C6 F8 DEC X1 DECREMENT EXP1.
F45D: 06 FB ASL M1+2
F45F: 26 FA ROL M1+1 SHIFT MANT1 (3 BYTES) LEFT.
F461: 26 F9 ROL M1
F463: A5 F8 NORM LDA X1 EXP1 ZERO?
F465: D0 EE BNE NORM1 NO, CONTINUE NORMALIZING.
F467: 60 RTS1 RTS RETURN.
F468: 20 A4 F4 FSUB JSR FCOMPL CMPL MANT1,CLEARS CARRY UNLESS 0
F46B: 20 7B F4 SWPALGN JSR ALGNSWP RIGHT SHIFT MANT1 OR SWAP WITH
F46E: A5 F4 FADD LDA X2
F470: C5 F8 CMP X1 COMPARE EXP1 WITH EXP2.
F472: D0 F7 BNE SWPALGN IF #,SWAP ADDENDS OR ALIGN MANTS.
F474: 20 25 F4 JSR ADD ADD ALIGNED MANTISSAS.
F477: 50 EA ADDEND BVC NORM NO OVERFLOW, NORMALIZE RESULT.
F479: 70 05 BVS RTLOG OV: SHIFT M1 RIGHT, CARRY INTO SIGN
F47B: 90 C4 ALGNSWP BCC SWAP SWAP IF CARRY CLEAR,
* ELSE SHIFT RIGHT ARITH.
F47D: A5 F9 RTAR LDA M1 SIGN OF MANT1 INTO CARRY FOR
F47F: 0A ASL RIGHT ARITH SHIFT.
F480: E6 F8 RTLOG INC X1 INCR X1 TO ADJUST FOR RIGHT SHIFT
F482: F0 75 BEQ OVFL EXP1 OUT OF RANGE.
F484: A2 FA RTLOG1 LDX #$FA INDEX FOR 6:BYTE RIGHT SHIFT.
F486: 76 FF ROR1 ROR E+3,X
F488: E8 INX NEXT BYTE OF SHIFT.
F489: D0 FB BNE ROR1 LOOP UNTIL DONE.
F48B: 60 RTS RETURN.
F48C: 20 32 F4 FMUL JSR MD1 ABS VAL OF MANT1, MANT2
F48F: 65 F8 ADC X1 ADD EXP1 TO EXP2 FOR PRODUCT EXP
F491: 20 E2 F4 JSR MD2 CHECK PROD. EXP AND PREP. FOR MUL
F494: 18 CLC CLEAR CARRY FOR FIRST BIT.
F495: 20 84 F4 MUL1 JSR RTLOG1 M1 AND E RIGHT (PROD AND MPLIER)
F498: 90 03 BCC MUL2 IF CARRY CLEAR, SKIP PARTIAL PROD
F49A: 20 25 F4 JSR ADD ADD MULTIPLICAND TO PRODUCT.
F49D: 88 MUL2 DEY NEXT MUL ITERATION.
F49E: 10 F5 BPL MUL1 LOOP UNTIL DONE.
F4A0: 46 F3 MDEND LSR SIGN TEST SIGN LSB.
F4A2: 90 BF NORMX BCC NORM IF EVEN,NORMALIZE PROD,ELSE COMP
F4A4: 38 FCOMPL SEC SET CARRY FOR SUBTRACT.
F4A5: A2 03 LDX #$3 INDEX FOR 3 BYTE SUBTRACT.
F4A7: A9 00 COMPL1 LDA #$0 CLEAR A.
F4A9: F5 F8 SBC X1,X SUBTRACT BYTE OF EXP1.
F4AB: 95 F8 STA X1,X RESTORE IT.
F4AD: CA DEX NEXT MORE SIGNIFICANT BYTE.
F4AE: D0 F7 BNE COMPL1 LOOP UNTIL DONE.
F4B0: F0 C5 BEQ ADDEND NORMALIZE (OR SHIFT RT IF OVFL).
F4B2: 20 32 F4 FDIV JSR MD1 TAKE ABS VAL OF MANT1, MANT2.
F4B5: E5 F8 SBC X1 SUBTRACT EXP1 FROM EXP2.
F4B7: 20 E2 F4 JSR MD2 SAVE AS QUOTIENT EXP.
F4BA: 38 DIV1 SEC SET CARRY FOR SUBTRACT.
F4BB: A2 02 LDX #$2 INDEX FOR 3-BYTE SUBTRACTION.
F4BD: B5 F5 DIV2 LDA M2,X
F4BF: F5 FC SBC E,X SUBTRACT A BYTE OF E FROM MANT2.
F4C1: 48 PHA SAVE ON STACK.
F4C2: CA DEX NEXT MORE SIGNIFICANT BYTE.
F4C3: 10 F8 BPL DIV2 LOOP UNTIL DONE.
F4C5: A2 FD LDX #$FD INDEX FOR 3-BYTE CONDITIONAL MOVE
F4C7: 68 DIV3 PLA PULL BYTE OF DIFFERENCE OFF STACK
F4C8: 90 02 BCC DIV4 IF M2<E THEN DON'T RESTORE M2.
F4CA: 95 F8 STA M2+3,X
F4CC: E8 DIV4 INX NEXT LESS SIGNIFICANT BYTE.
F4CD: D0 F8 BNE DIV3 LOOP UNTIL DONE.
F4CF: 26 FB ROL M1+2
F4D1: 26 FA ROL M1+1 ROLL QUOTIENT LEFT, CARRY INTO LSB
F4D3: 26 F9 ROL M1
F4D5: 06 F7 ASL M2+2
F4D7: 26 F6 ROL M2+1 SHIFT DIVIDEND LEFT
F4D9: 26 F5 ROL M2
F4DB: B0 1C BCS OVFL OVFL IS DUE TO UNNORMED DIVISOR
F4DD: 88 DEY NEXT DIVIDE ITERATION.
F4DE: D0 DA BNE DIV1 LOOP UNTIL DONE 23 ITERATIONS.
F4E0: F0 BE BEQ MDEND NORM. QUOTIENT AND CORRECT SIGN.
F4E2: 86 FB MD2 STX M1+2
F4E4: 86 FA STX M1+1 CLEAR MANT1 (3 BYTES) FOR MUL/DIV.
F4E6: 86 F9 STX M1
F4E8: B0 0D BCS OVCHK IF CALC. SET CARRY,CHECK FOR OVFL
F4EA: 30 04 BMI MD3 IF NEG THEN NO UNDERFLOW.
F4EC: 68 PLA POP ONE RETURN LEVEL.
F4ED: 68 PLA
F4EE: 90 B2 BCC NORMX CLEAR X1 AND RETURN.
F4F0: 49 80 MD3 EOR #$80 COMPLEMENT SIGN BIT OF EXPONENT.
F4F2: 85 F8 STA X1 STORE IT.
F4F4: A0 17 LDY #$17 COUNT 24 MUL/23 DIV ITERATIONS.
F4F6: 60 RTS RETURN.
F4F7: 10 F7 OVCHK BPL MD3 IF POSITIVE EXP THEN NO OVFL.
F4F9: 4C F5 03 OVFL JMP OVLOC
ORG $F63D
F63D: 20 7D F4 FIX1 JSR RTAR
F640: A5 F8 FIX LDA X1
F642: 10 13 BPL UNDFL
F644: C9 8E CMP #$8E
F646: D0 F5 BNE FIX1
F648: 24 F9 BIT M1
F64A: 10 0A BPL FIXRTS
F64C: A5 FB LDA M1+2
F64E: F0 06 BEQ FIXRTS
F650: E6 FA INC M1+1
F652: D0 02 BNE FIXRTS
F654: E6 F9 INC M1
F656: 60 FIXRTS RTS
F657: A9 00 UNDFL LDA #$0
F659: 85 F9 STA M1
F65B: 85 FA STA M1+1
F65D: 60 RTS
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