100 REM FASTER SQUARE ROOT PAL SOURCE
110 OPEN8,8,1,"0:FAST SQR.OBJ
120 [158] 700
130 .OPT O8
140 [172][178] $C000
150 ; FASTER SQUARE ROOT
160 ; TAKES FIRST BASIC VARIABLE [175]
170 ; [142]S SQUARE ROOT IN ITS PLACE
180 ; USES [162][164]N'S METHOD WITH A [203]OD
190 ; FIRST APPROXIMATI[145].
200 ;
210 VAR [178] $2D ; START OF VARIABLES
220 PTR [178] $AA ; PO[181]S [164] VARIABLE
230 CTR [178] $AC ; ITERATI[145] COUNTER
240 TEMP [178] $5C ; TEMP S[164]RE [129] FLT PT #
250 ;
260 ; ROM ROUTINES
270 TEMF1 [178] $BBA2 ; UNPACK 5C [164] FAC#1
280 DIVID [178] $BB0F ; FAC#1[178]VAR[173]FAC#1
290 PLUS [178] $B867  ;FAC#1[178]FAC#2[170]FAC#1
300 F1TEM [178] $BBC7 ; PACK FAC#1 [164] 5C
310 F1MEM [178] $BBD4 ; PACK FAC#1 [164] MEM[176]Y
320 [153] [178] $FFD2 ; CHROUT ROUTINE
330 ;
340 LDY #$03    ;[161] VARIABLE'S MANTISSA
350 LDA (VAR),Y ;CHECK [139] NEGATIVE
360 BMI ERR[176]EXIT
370 DEY
380 LDA (VAR),Y ;[161] VARIABLE'S [189][145]ENT
390 BEQ [142]  ;[142] [139] VAR[178]ZERO
400 LDA VAR     ;PO[181]S [164] VAR NAME
410 CLC
420 ADC #$02    ;ADD 2 SO PTR
430 STA PTR     ;PO[181]S [164] VARIABLE
440 LDA VAR[170]1   ;[175] S[164]RE IT
450 ADC #$00
460 STA PTR[170]1
470 LDY #$0     ;FILL TEMP WITH ZEROES
480 STY TEMP[170]1
490 STY TEMP[170]2
500 STY TEMP[170]3
510 STY TEMP[170]4
520 ;
530 ; NOW FIND A FIRST APPROXIMATI[145]
540 ; [164] THE SQUARE ROOT
550 ; [189][145]ENT[178]  [189][145]ENT[173]2 [170]40.5
560 ; MANTISSA FOUND FROM TABLE
570 LDA (PTR),Y ;[161] [189][145]ENT  (Y[178]0)
580 R[176]        ;A[178]A[173]A, POP LOW BIT
590 ;   CARRY[178]1 WHEN [189][145]ENT ODD
600 BCS ADD    ;NO FLAG SET [139] ODD
610 LDX #$80   ;EVEN, SO SET A FLAG BIT
620 STX TEMP[170]1
630 ADD ADC #$40 ;A[178][189][145]ENT OF 1ST APPR
640 STA TEMP   ;S[164]RE [189][145]ENT
650 INY        ;Y[178]1
660 LDA (PTR),Y ;MANTISSA OF VARIABLE
670 [176]A TEMP[170]1 ;[139] [189][145] ODD ADD 80
680 LSR            ;SH[139]T NYBBLE RIGHT
690 LSR
700 LSR
710 LSR
720 TAX
730 LDA TABL,X ;[161] APPROX FROM TABLE
740 STA TEMP[170]1 ;S[164]RE IT IN TEMP MANTISSA
750 ; NOW USE [162][164]N'S METHOD
760 ; X[178](X[170]VAR[173]X)[173]2
770 LDA #$04
780 STA CTR   ;SET COUNTER [164] 4
790 LDA #[179]TEMP
800 LDY #0
810 JSR TEMF1 ;[147] FAC#1 FROM TEMP
820 LOOP LDA PTR
830 LDY PTR[170]1
840 JSR DIVID ;DIVIDE FAC#1 [181]O VAR
850 LDA #[179]TEMP
860 LDY #0
870 JSR PLUS  ;ADD TEMP [164] FAC#1
880 DEC $61   ;DIVIDE FAC#1 BY 2
890 JSR F1TEM ;PACK FAC#1 [164] TEMP
900 DEC CTR   ;DEC[143]ENT THE COUNTER
910 BNE LOOP  ;LOOP [139] [168] ZERO
920 LDX PTR
930 LDY PTR[170]1
940 JSR F1MEM ;PACK FAC#1 [164] MEM[176]Y
950 [142] RTS
960 ERR[176]EXIT LDA #$3F ; "?"
970 JSR [153]          ;[153] "?"
980 RTS
990 TABL .BYTE 03,11,18,25,32,38,44,50
1000 .BYTE 58,69,79,89,98,107,115,123
1010 .[128]