0100 ;MACHINE LANGUAGE SORTS, PART 1›0110 ;BY KEVIN PECK›0120 ;(c)1987, ANTIC PUBLISHING›0130 FLAST = $00     ;End, outer loop›0140 FLENKEY = $CB   ;Key length›0150 RLEN =  $CC     ;Record Length›0160 OFFSETKEY = $CF ;Key offset›0170 FIRST = $CD     ;1st element ptr›0180 SECOND = $D4    ;2nd element ptr›0190 LAST =  $D6     ;End, inner loop›0200 FENDKEY = $D8   ;End, key field›0210 ORDER = $E1     ;Order, sort 0,1›0220 FLENSEC = $D0   ;2nd field lngth›0230 OFFSETSEC = $E0 ;2nd  " " offset›0240 FENDSEC = $D1   ;End 2nd field›0250 ;›0260     *=  $4000›0270 ;›0280     CLD ›0290     PLA ›0300 ; Retrieve arguments from BASIC›0310     PLA ›0320     STA FIRST+1›0330     PLA ›0340     STA FIRST›0350     PLA ›0360     STA LAST+1›0370     PLA ›0380     STA LAST›0390     PLA ›0400     PLA ›0410     STA FLENKEY›0420     PLA ›0430     PLA ›0440     STA OFFSETKEY›0450     CLC         ;Find end of ›0460     ADC FLENKEY ;First key  ›0470     STA FENDKEY›0480     PLA ›0490     PLA ›0500     STA FLENSEC›0510     PLA ›0520     PLA ›0530     STA OFFSETSEC›0540     CLC ›0550     ADC FLENSEC ;Find end of ›0560     STA FENDSEC ;second key›0570     PLA ›0580     PLA ›0590     STA RLEN›0600     PLA ›0610     PLA ›0620     STA ORDER›0630 ;›0640 ; All parms. now in zero page.›0650 ; Next, set pointer to the end›0660 ; of the outer loop›0670     LDA LAST+1›0680     STA FLAST+1›0690     SEC ›0700     LDA LAST›0710     SBC RLEN›0720     STA FLAST›0730     BCS SETSECOND›0740 ;›0750     DEC FLAST+1›0760 ; Start of outer loop.›0770 ; Adjust the second pointer to›0780 ; point to the first pointer›0790 ; plus the record length.›0800 ;›0810 SETSECOND›0820     CLC ›0830     LDA FIRST+1›0840     STA SECOND+1›0850     LDA FIRST›0860     ADC RLEN›0870     STA SECOND›0880     BCC SORTKEY›0890     INC SECOND+1›0900 ; Start of the inner loop.›0910 ; 1. Compare the Key field of›0920 ;    the two sort elements.›0930 ; 2. If we find a mismatch,›0940 ;    do we need to swap them?›0950 SORTKEY›0960     LDY OFFSETKEY›0970 ;›0980 KEYLOOP›0990 ;›1000     LDA (FIRST),Y ;get a byte›1010     CMP (SECOND),Y ;of each.›1020     BEQ CHKMORE ;If = Continue.›1030 ;›1040     BCC NOSWAP  ;If F<S no swap.›1050 ;›1060     BCS SWAP    ;If F>S swap.›1070 ;›1080 CHKMORE›1090 ;›1100     INY         ;Adjust pointer›1110     CPY FENDKEY ;All done?›1120     BNE KEYLOOP ;No.  Continue.›1130 ;›1140 ; At this point, all bytes in›1150 ; the key field of both sort›1160 ; elements are equal.  Drop to›1170 ; SORTSECOND and check the›1180 ; secondary fields.›1190 ;   If their lengths = 0, then›1200 ; we don't have 2ndry fields.›1210 ; We are only doing a one-field›1220 ; sort--goto the Noswap routine.›1230 ; If the key fields are equal,›1240 ; there is no need to swap them.›1250 ;›1260 SORTSEC›1270     LDA FLENSEC ;A second field?›1280     BEQ NOSWAPBD ;No.›1290 ;›1300     LDY OFFSETSEC›1310 SECLOOP›1320     LDA (FIRST),Y ;Compare byte›1330     CMP (SECOND),Y ;by byte...›1340     BEQ CHKMORE2 ;If = do more.›1350 ;›1360     BCC NOSWAP  ;If F<S Noswap.›1370 ;›1380     BCS SWAP    ;If F>s Swap.›1390 ;›1400 CHKMORE2›1410     INY         ;Point to next.›1420     CPY FENDSEC ;End of 2nd?›1430     BNE SECLOOP ;No, do more.›1440 ;›1450 ; Now, both the key and the›1460 ; secondary fields of both sort›1470 ; elemtents are equal. Goto›1480 ; the noswap routine through the›1490 ; "back door." No need to check›1500 ; the order, no need to swap.›1510     BEQ NOSWAPBD›1520 ;›1530 ; This is where the swapping›1540 ; occurs. First, check the›1550 ; swapping order.›1560 ; (Assume swapping in ascending›1570 ; order.) If order<>0, then›1580 ; sort in descending order.›1590 ;›1600 SWAP›1610 ;›1620     LDA ORDER   ;Get order›1630     BNE NOSWAPBD ;Not 0, No swap›1640 ;›1650 ; Swap routine's back door.›1660 ; If NOSWAP decides we need to›1670 ; swap by checking the order,›1680 ; we need to come here (instead›1690 ; of SWAP) or we would go into›1700 ; a continuous loop.›1710 ;›1720 SWAPBD›1730     LDY #0›1740 SWAPLOOP›1750     LDA (FIRST),Y ;Key byte›1760     PHA         ;  to stack.›1770     LDA (SECOND),Y ; 2ndry byte›1780     STA (FIRST),Y ;  to key.›1790     PLA         ;Key from stack›1800     STA (SECOND),Y ;to 2ndry.›1810     INY         ;Next byte.›1820     CPY RLEN    ; More?›1830     BNE SWAPLOOP ;Yes. Continue.›1840 ;›1850 ; All bytes have been swapped.›1860 ; Now adjust pointers to the›1870 ; next elements for the sort.›1880 ;  Goto the noswap back door.›1890 ;›1900     BEQ NOSWAPBD›1910 ;›1920 NOSWAP›1930 ;›1940     LDA ORDER   ;Is ORDER=1?›1950     BNE SWAPBD  ;Yes. Swap them›1960 ;›1970 NOSWAPBD›1980     CLC ›1990     LDA SECOND›2000     ADC RLEN›2010     STA SECOND›2020     LDA SECOND+1›2030     ADC #0›2040     STA SECOND+1›2050     CMP LAST+1›2060     BNE SORTKEY›2070 ;›2080     LDA SECOND›2090     CMP LAST›2100     BNE SORTKEY›2110 ;›2120 ; We've made one pass through›2130 ; the sort's inner loop.  Now,›2140 ; adjust the outer loop and›2150 ; check if we're done with it.›2160 ; If not, readjust the inner›2170 ; loop pointer to the outer loop›2180 ; pointer + the record length.›2190 ;›2200     CLC ›2210     LDA FIRST›2220     ADC RLEN›2230     STA FIRST›2240     LDA FIRST+1›2250     ADC #0›2260     STA FIRST+1›2270     CMP FLAST+1›2280     BNE SETSECOND›2290 ;›2300     LDA FIRST›2310     CMP FLAST›2320     BNE SETSECOND›2330 ;›2340     RTS         ;Goto BASIC›2350     .END ›