Not so much a bug, as slow!

[britlion]

Okay. Fairly convinced there's a bug here.

zxb version 1.3.0-S928

Here's an expanded program in full - was looking at perhaps faster squaring?

Anyway, the retruned value is weird.

A statement of: print x;" ";fastSquares(ABS x);" = ";CAST(uLong, x)*x ;"[]"

Comes back lines like

-61 3721 = 3721 [] 0 []

There's no way it should print anything after it's confirmed the function does the same thing as the X*X calculation. No [] twice. (I put that on the end because it was adding a bunch of zeroes instead without it!)

Code:

FUNCTION t() as uLong asm DI LD DE,(23674) LD D,0 LD HL,(23672) EI end asm end function FUNCTION FASTCALL fastSquares (number as Byte) as uInteger ASM ; Calculates (number^2) - does this by the fastest (and most size expensive) method - lookup table. ; This function arrives with "number" - a byte in register A AND A ; Set flags based on A BIT 7,a ; Check if this is a negative number JR Z,fastSquaresStart ; No? We jump into main routine. NEG ; Negate A to make it positive. fastSquaresStart: ADD A,A ; Think of this as A=A+A - that is it doubles the value in A (Because each entry in our table is 2 bytes long) LD C,A ; LET C=A LD B,0 ; LET B=0 LD HL,SquaresTable ; LET HL=address Of Table of HalfSquares. ADD HL,BC ; ADD the value in BC to the value in HL - means that HL is the address of the answer result. LD A,(HL) ; LET A=PEEK (HL) INC HL ; HL=HL+1 LD L,(HL) ; LET L=PEEK (HL) LD H,A ; LET H=A RET ; Return - with the answere in HL (High byte in H, Low Byte in L) ;table of (a^2) SquaresTable: DEFB 0,0 ;0^2=0 DEFB 0,1 ;1^2=1 DEFB 0,4 ;2^2=4 DEFB 0,9 ;3^2=9 DEFB 0,16 ;4^2=16 DEFB 0,25 ;5^2=25 DEFB 0,36 ;6^2=36 DEFB 0,49 ;7^2=49 DEFB 0,64 ;8^2=64 DEFB 0,81 ;9^2=81 DEFB 0,100 ;10^2=100 DEFB 0,121 ;11^2=121 DEFB 0,144 ;12^2=144 DEFB 0,169 ;13^2=169 DEFB 0,196 ;14^2=196 DEFB 0,225 ;15^2=225 DEFB 1,0 ;16^2=256 DEFB 1,33 ;17^2=289 DEFB 1,68 ;18^2=324 DEFB 1,105 ;19^2=361 DEFB 1,144 ;20^2=400 DEFB 1,185 ;21^2=441 DEFB 1,228 ;22^2=484 DEFB 2,17 ;23^2=529 DEFB 2,64 ;24^2=576 DEFB 2,113 ;25^2=625 DEFB 2,164 ;26^2=676 DEFB 2,217 ;27^2=729 DEFB 3,16 ;28^2=784 DEFB 3,73 ;29^2=841 DEFB 3,132 ;30^2=900 DEFB 3,193 ;31^2=961 DEFB 4,0 ;32^2=1024 DEFB 4,65 ;33^2=1089 DEFB 4,132 ;34^2=1156 DEFB 4,201 ;35^2=1225 DEFB 5,16 ;36^2=1296 DEFB 5,89 ;37^2=1369 DEFB 5,164 ;38^2=1444 DEFB 5,241 ;39^2=1521 DEFB 6,64 ;40^2=1600 DEFB 6,145 ;41^2=1681 DEFB 6,228 ;42^2=1764 DEFB 7,57 ;43^2=1849 DEFB 7,144 ;44^2=1936 DEFB 7,233 ;45^2=2025 DEFB 8,68 ;46^2=2116 DEFB 8,161 ;47^2=2209 DEFB 9,0 ;48^2=2304 DEFB 9,97 ;49^2=2401 DEFB 9,196 ;50^2=2500 DEFB 10,41 ;51^2=2601 DEFB 10,144 ;52^2=2704 DEFB 10,249 ;53^2=2809 DEFB 11,100 ;54^2=2916 DEFB 11,209 ;55^2=3025 DEFB 12,64 ;56^2=3136 DEFB 12,177 ;57^2=3249 DEFB 13,36 ;58^2=3364 DEFB 13,153 ;59^2=3481 DEFB 14,16 ;60^2=3600 DEFB 14,137 ;61^2=3721 DEFB 15,4 ;62^2=3844 DEFB 15,129 ;63^2=3969 DEFB 16,0 ;64^2=4096 DEFB 16,129 ;65^2=4225 DEFB 17,4 ;66^2=4356 DEFB 17,137 ;67^2=4489 DEFB 18,16 ;68^2=4624 DEFB 18,153 ;69^2=4761 DEFB 19,36 ;70^2=4900 DEFB 19,177 ;71^2=5041 DEFB 20,64 ;72^2=5184 DEFB 20,209 ;73^2=5329 DEFB 21,100 ;74^2=5476 DEFB 21,249 ;75^2=5625 DEFB 22,144 ;76^2=5776 DEFB 23,41 ;77^2=5929 DEFB 23,196 ;78^2=6084 DEFB 24,97 ;79^2=6241 DEFB 25,0 ;80^2=6400 DEFB 25,161 ;81^2=6561 DEFB 26,68 ;82^2=6724 DEFB 26,233 ;83^2=6889 DEFB 27,144 ;84^2=7056 DEFB 28,57 ;85^2=7225 DEFB 28,228 ;86^2=7396 DEFB 29,145 ;87^2=7569 DEFB 30,64 ;88^2=7744 DEFB 30,241 ;89^2=7921 DEFB 31,164 ;90^2=8100 DEFB 32,89 ;91^2=8281 DEFB 33,16 ;92^2=8464 DEFB 33,201 ;93^2=8649 DEFB 34,132 ;94^2=8836 DEFB 35,65 ;95^2=9025 DEFB 36,0 ;96^2=9216 DEFB 36,193 ;97^2=9409 DEFB 37,132 ;98^2=9604 DEFB 38,73 ;99^2=9801 DEFB 39,16 ;100^2=10000 DEFB 39,217 ;101^2=10201 DEFB 40,164 ;102^2=10404 DEFB 41,113 ;103^2=10609 DEFB 42,64 ;104^2=10816 DEFB 43,17 ;105^2=11025 DEFB 43,228 ;106^2=11236 DEFB 44,185 ;107^2=11449 DEFB 45,144 ;108^2=11664 DEFB 46,105 ;109^2=11881 DEFB 47,68 ;110^2=12100 DEFB 48,33 ;111^2=12321 DEFB 49,0 ;112^2=12544 DEFB 49,225 ;113^2=12769 DEFB 50,196 ;114^2=12996 DEFB 51,169 ;115^2=13225 DEFB 52,144 ;116^2=13456 DEFB 53,121 ;117^2=13689 DEFB 54,100 ;118^2=13924 DEFB 55,81 ;119^2=14161 DEFB 56,64 ;120^2=14400 DEFB 57,49 ;121^2=14641 DEFB 58,36 ;122^2=14884 DEFB 59,25 ;123^2=15129 DEFB 60,16 ;124^2=15376 DEFB 61,9 ;125^2=15625 DEFB 62,4 ;126^2=15876 DEFB 63,1 ;127^2=16129 DEFB 64,0 ;128^2=16384 DEFB 65,1 ;129^2=16641 DEFB 66,4 ;130^2=16900 DEFB 67,9 ;131^2=17161 DEFB 68,16 ;132^2=17424 DEFB 69,25 ;133^2=17689 DEFB 70,36 ;134^2=17956 DEFB 71,49 ;135^2=18225 DEFB 72,64 ;136^2=18496 DEFB 73,81 ;137^2=18769 DEFB 74,100 ;138^2=19044 DEFB 75,121 ;139^2=19321 DEFB 76,144 ;140^2=19600 DEFB 77,169 ;141^2=19881 DEFB 78,196 ;142^2=20164 DEFB 79,225 ;143^2=20449 DEFB 81,0 ;144^2=20736 DEFB 82,33 ;145^2=21025 DEFB 83,68 ;146^2=21316 DEFB 84,105 ;147^2=21609 DEFB 85,144 ;148^2=21904 DEFB 86,185 ;149^2=22201 DEFB 87,228 ;150^2=22500 DEFB 89,17 ;151^2=22801 DEFB 90,64 ;152^2=23104 DEFB 91,113 ;153^2=23409 DEFB 92,164 ;154^2=23716 DEFB 93,217 ;155^2=24025 DEFB 95,16 ;156^2=24336 DEFB 96,73 ;157^2=24649 DEFB 97,132 ;158^2=24964 DEFB 98,193 ;159^2=25281 DEFB 100,0 ;160^2=25600 DEFB 101,65 ;161^2=25921 DEFB 102,132 ;162^2=26244 DEFB 103,201 ;163^2=26569 DEFB 105,16 ;164^2=26896 DEFB 106,89 ;165^2=27225 DEFB 107,164 ;166^2=27556 DEFB 108,241 ;167^2=27889 DEFB 110,64 ;168^2=28224 DEFB 111,145 ;169^2=28561 DEFB 112,228 ;170^2=28900 DEFB 114,57 ;171^2=29241 DEFB 115,144 ;172^2=29584 DEFB 116,233 ;173^2=29929 DEFB 118,68 ;174^2=30276 DEFB 119,161 ;175^2=30625 DEFB 121,0 ;176^2=30976 DEFB 122,97 ;177^2=31329 DEFB 123,196 ;178^2=31684 DEFB 125,41 ;179^2=32041 DEFB 126,144 ;180^2=32400 DEFB 127,249 ;181^2=32761 DEFB 129,100 ;182^2=33124 DEFB 130,209 ;183^2=33489 DEFB 132,64 ;184^2=33856 DEFB 133,177 ;185^2=34225 DEFB 135,36 ;186^2=34596 DEFB 136,153 ;187^2=34969 DEFB 138,16 ;188^2=35344 DEFB 139,137 ;189^2=35721 DEFB 141,4 ;190^2=36100 DEFB 142,129 ;191^2=36481 DEFB 144,0 ;192^2=36864 DEFB 145,129 ;193^2=37249 DEFB 147,4 ;194^2=37636 DEFB 148,137 ;195^2=38025 DEFB 150,16 ;196^2=38416 DEFB 151,153 ;197^2=38809 DEFB 153,36 ;198^2=39204 DEFB 154,177 ;199^2=39601 DEFB 156,64 ;200^2=40000 DEFB 157,209 ;201^2=40401 DEFB 159,100 ;202^2=40804 DEFB 160,249 ;203^2=41209 DEFB 162,144 ;204^2=41616 DEFB 164,41 ;205^2=42025 DEFB 165,196 ;206^2=42436 DEFB 167,97 ;207^2=42849 DEFB 169,0 ;208^2=43264 DEFB 170,161 ;209^2=43681 DEFB 172,68 ;210^2=44100 DEFB 173,233 ;211^2=44521 DEFB 175,144 ;212^2=44944 DEFB 177,57 ;213^2=45369 DEFB 178,228 ;214^2=45796 DEFB 180,145 ;215^2=46225 DEFB 182,64 ;216^2=46656 DEFB 183,241 ;217^2=47089 DEFB 185,164 ;218^2=47524 DEFB 187,89 ;219^2=47961 DEFB 189,16 ;220^2=48400 DEFB 190,201 ;221^2=48841 DEFB 192,132 ;222^2=49284 DEFB 194,65 ;223^2=49729 DEFB 196,0 ;224^2=50176 DEFB 197,193 ;225^2=50625 DEFB 199,132 ;226^2=51076 DEFB 201,73 ;227^2=51529 DEFB 203,16 ;228^2=51984 DEFB 204,217 ;229^2=52441 DEFB 206,164 ;230^2=52900 DEFB 208,113 ;231^2=53361 DEFB 210,64 ;232^2=53824 DEFB 212,17 ;233^2=54289 DEFB 213,228 ;234^2=54756 DEFB 215,185 ;235^2=55225 DEFB 217,144 ;236^2=55696 DEFB 219,105 ;237^2=56169 DEFB 221,68 ;238^2=56644 DEFB 223,33 ;239^2=57121 DEFB 225,0 ;240^2=57600 DEFB 226,225 ;241^2=58081 DEFB 228,196 ;242^2=58564 DEFB 230,169 ;243^2=59049 DEFB 232,144 ;244^2=59536 DEFB 234,121 ;245^2=60025 DEFB 236,100 ;246^2=60516 DEFB 238,81 ;247^2=61009 DEFB 240,64 ;248^2=61504 DEFB 242,49 ;249^2=62001 DEFB 244,36 ;250^2=62500 DEFB 246,25 ;251^2=63001 DEFB 248,16 ;252^2=63504 DEFB 250,9 ;253^2=64009 DEFB 252,4 ;254^2=64516 DEFB 254,1 ;255^2=65025 END ASM END FUNCTION DIM x,y as integer DIM time as uLONG 'time=t() ' For x=-100 To 100 For y=-100 To 100 'If ((x<<1)-25)*((x<<1)-25)+(y-50)*(y-50)<200 Or ((x<<1)+25)*((x<<1)+25)+(y-50)*(y-50)<200 then plot x+100,96-y 'END IF print x;" ";fastSquares(ABS x);" = ";CAST(uLong, x)*x ;"[]" Next y Next x 'time=t()-time 'print CAST(float,time)/50