mads 1.9.0 build 21 (16 Aug 09) Source: C:\Users\Rudla\Projects\atalan\src\test/sieve_b.asm 1 = 0080 _arr equ 128 2 = 0034 _TEMPW2 equ 52 3 = 0014 rtclock1 equ 20 4 = 0013 rtclock2 equ 19 5 = 0082 count equ 130 6 = 0084 _s0__i equ 132 7 = 0086 _s1__i equ 134 8 = 0087 _s1___3 equ 135 9 = 0088 _s1___4 equ 136 10 = 0089 _s2__k equ 137 11 = 008B _s2___7 equ 139 12 = 008D _s2___8 equ 141 13 = 008F _s2___9 equ 143 14 = 0091 _s3__k equ 145 15 = 0093 _s3___12 equ 147 16 = 0095 t equ 149 17 = 0097 _17 equ 151 18 = 0098 _18 equ 152 19 = 0099 _19 equ 153 20 = 009A _20 equ 154 21 = 009B _21 equ 155 22 org $2e0 23 FFFF> 02E0-02E1> 00 20 dta a($2000) 24 02E2 org $2000 25 ;### sieve_b.atl(13) rtclock1 = 0 26 2000-217E> A9 00 lda #0 27 2002 85 14 sta rtclock1 28 ;### sieve_b.atl(14) rtclock2 = 0 29 2004 85 13 sta rtclock2 30 ;### sieve_b.atl(19) for i:0..$1fff flags(i)=$aa 31 2006 85 85 sta _s0__i+1 32 2008 A8 tay 33 2009 _lbl2: 34 2009 A9 7F lda #flags 37 200F 18 clc 38 2010 65 85 adc _s0__i+1 39 2012 85 81 sta _arr+1 40 2014 A9 AA lda #170 41 2016 91 80 sta (_arr),y 42 2018 C8 iny 43 2019 D0 02 jne _lbl9 44 201B E6 85 inc _s0__i+1 45 201D _lbl9: 46 201D C0 00 cpy #0 47 201F D0 E8 jne _lbl2 48 2021 A5 85 lda _s0__i+1 49 2023 C9 20 cmp #32 50 2025 D0 E2 jne _lbl2 51 ;### sieve_b.atl(21) for i:3..255 step 2 where (flags(i/8) and mask(i mod 8) <> 0) 52 2027 A9 03 lda #3 53 2029 85 86 sta _s1__i 54 202B _lbl6: 55 202B A5 86 lda _s1__i 56 202D 4A lsr 57 202E 4A lsr 58 202F 4A lsr 59 2030 85 87 sta _s1___3 60 2032 A5 86 lda _s1__i 61 2034 29 07 and #7 62 2036 85 88 sta _s1___4 63 2038 A6 87 ldx _s1___3 64 203A BD 7F 21 lda flags,x 65 203D 85 97 sta _17 66 203F A6 88 ldx _s1___4 67 2041 BD 6F 21 lda mask,x 68 2044 25 97 and _17 69 2046 C9 00 cmp #0 70 2048 D0 03 4C CF 20 jeq _lbl10 71 ;### sieve_b.atl(22) for k:i*i..8192 step 2*i 72 204D A5 86 lda _s1__i 73 204F A6 86 ldx _s1__i 74 2051 20 73 42 jsr _sys_mul8 75 2054 A5 86 lda _s1__i 76 2056 0A asl 77 2057 85 8B sta _s2___7 78 2059 A9 00 lda #0 79 205B 2A rol 80 205C 85 8C sta _s2___7+1 81 205E A5 34 lda _TEMPW2 82 2060 85 89 sta _s2__k 83 2062 A5 35 lda _TEMPW2+1 84 2064 85 8A sta _s2__k+1 85 2066 _lbl5: 86 ;### sieve_b.atl(23) flags(k/8) = flags(k/8) and maskx(k mod 8) 87 2066 A5 89 lda _s2__k 88 2068 85 8D sta _s2___8 89 206A A5 8A lda _s2__k+1 90 206C 4A lsr 91 206D 66 8D ror _s2___8+0 92 206F 4A lsr 93 2070 66 8D ror _s2___8+0 94 2072 4A lsr 95 2073 66 8D ror _s2___8+0 96 2075 85 8E sta _s2___8+1 97 2077 A5 89 lda _s2__k 98 2079 85 8F sta _s2___9 99 207B A5 8A lda _s2__k+1 100 207D 4A lsr 101 207E 66 8F ror _s2___9+0 102 2080 4A lsr 103 2081 66 8F ror _s2___9+0 104 2083 4A lsr 105 2084 66 8F ror _s2___9+0 106 2086 85 90 sta _s2___9+1 107 2088 A5 89 lda _s2__k 108 208A 29 07 and #7 109 208C AA tax 110 208D A9 7F lda #flags 113 2093 18 clc 114 2094 65 90 adc _s2___9+1 115 2096 85 81 sta _arr+1 116 2098 A4 8F ldy _s2___9+0 117 209A B1 80 lda (_arr),y 118 209C 85 98 sta _18 119 209E BD 77 21 lda maskx,x 120 20A1 85 9A sta _20 121 20A3 A5 98 lda _18 122 20A5 25 9A and _20 123 20A7 85 9B sta _21 124 20A9 A9 21 lda #>flags 125 20AB 18 clc 126 20AC 65 8E adc _s2___8+1 127 20AE 85 81 sta _arr+1 128 20B0 A4 8D ldy _s2___8+0 129 20B2 A5 9B lda _21 130 20B4 91 80 sta (_arr),y 131 20B6 A5 89 lda _s2__k 132 20B8 18 clc 133 20B9 65 8B adc _s2___7+0 134 20BB 85 89 sta _s2__k 135 20BD A5 8A lda _s2__k+1 136 20BF 65 8C adc _s2___7+1 137 20C1 85 8A sta _s2__k+1 138 20C3 C9 20 cmp #32 139 20C5 90 9F jcc _lbl5 140 20C7 D0 06 jne _lbl10 141 20C9 A5 89 lda _s2__k 142 20CB C9 00 cmp #0 143 20CD 90 97 jcc _lbl5 144 20CF _lbl10: 145 20CF A5 86 lda _s1__i 146 20D1 18 clc 147 20D2 69 02 adc #2 148 20D4 85 86 sta _s1__i 149 20D6 C9 01 cmp #1 150 20D8 F0 03 4C 2B 20 jne _lbl6 151 ;### sieve_b.atl(25) count = 1 152 20DD A9 01 lda #1 153 20DF 85 82 sta count 154 20E1 A9 00 lda #0 155 20E3 85 83 sta count+1 156 ;### sieve_b.atl(26) for k:3..8192 step 2 where (flags(k/8) and mask(k mod 8) <> 0) 157 20E5 A9 03 lda #3 158 20E7 85 91 sta _s3__k 159 20E9 A9 00 lda #0 160 20EB 85 92 sta _s3__k+1 161 20ED _lbl8: 162 20ED A5 91 lda _s3__k 163 20EF 85 93 sta _s3___12 164 20F1 A5 92 lda _s3__k+1 165 20F3 4A lsr 166 20F4 66 93 ror _s3___12+0 167 20F6 4A lsr 168 20F7 66 93 ror _s3___12+0 169 20F9 4A lsr 170 20FA 66 93 ror _s3___12+0 171 20FC 85 94 sta _s3___12+1 172 20FE A5 91 lda _s3__k 173 2100 29 07 and #7 174 2102 AA tax 175 2103 A9 7F lda #flags 178 2109 18 clc 179 210A 65 94 adc _s3___12+1 180 210C 85 81 sta _arr+1 181 210E A4 93 ldy _s3___12+0 182 2110 B1 80 lda (_arr),y 183 2112 85 99 sta _19 184 2114 BD 6F 21 lda mask,x 185 2117 25 99 and _19 186 2119 C9 00 cmp #0 187 211B F0 06 jeq _lbl11 188 ;### sieve_b.atl(27) inc count 189 211D E6 82 inc count+0 190 211F D0 02 jne _lbl11 191 2121 E6 83 inc count+1 192 2123 _lbl11: 193 2123 A5 91 lda _s3__k 194 2125 18 clc 195 2126 69 02 adc #2 196 2128 85 91 sta _s3__k 197 212A 90 02 jcc _lbl12 198 212C E6 92 inc _s3__k+1 199 212E _lbl12: 200 212E A5 91 lda _s3__k 201 2130 C9 01 cmp #1 202 2132 D0 B9 jne _lbl8 203 2134 A5 92 lda _s3__k+1 204 2136 C9 20 cmp #32 205 2138 D0 B3 jne _lbl8 206 ;### sieve_b.atl(29) t = rtclock2 * 256 + rtclock1 207 213A A9 00 lda #0 208 213C 18 clc 209 213D 65 14 adc rtclock1 210 213F 85 95 sta t 211 2141 A5 13 lda rtclock2 212 2143 69 00 adc #0 213 2145 85 96 sta t+1 214 ;### sieve_b.atl(31) "[count] prime numbers in [t] ticks" 215 2147 20 7F 41 jsr _std_print_out 216 214A 82 82 00 dta b(130),a(count) 217 214D 12 20 70 72 69 6D + dta b(18),c' prime numbers in ' 218 2160 82 95 00 dta b(130),a(t) 219 2163 06 20 74 69 63 6B + dta b(6),c' ticks' 220 216A 80 dta b(128) 221 216B 00 dta b(0) 222 216C _lbl13: 223 216C 4C 6C 21 jmp _lbl13 224 216F mask: 225 ;### sieve_b.atl(8) mask:array(0..7) = 1,2,4,8,16,32,64,128 226 216F 01 dta b(1) 227 2170 02 dta b(2) 228 2171 04 dta b(4) 229 2172 08 dta b(8) 230 2173 10 dta b(16) 231 2174 20 dta b(32) 232 2175 40 dta b(64) 233 2176 80 dta b(128) 234 2177 maskx: 235 ;### sieve_b.atl(9) maskx:array(0..7) = %1111__1110,%1111__1101,%1111__1011,%1111__0111,%1110__1111,%1101__1111,%1011__1111,%0111__1111 236 2177 FE dta b(254) 237 2178 FD dta b(253) 238 2179 FB dta b(251) 239 217A F7 dta b(247) 240 217B EF dta b(239) 241 217C DF dta b(223) 242 217D BF dta b(191) 243 217E 7F dta b(127) 244 217F flags: 245 = 217F .ds 8192 246 417F icl 'C:\Users\Rudla\Projects\atalan\src\platform\atari\atari.asm' Source: C:\Users\Rudla\Projects\atalan\src\platform\atari\atari.asm 1 ;******************************************************** 2 ; 3 ; ATALAN Atari standard library 4 ; 5 ; Parts of code have been taken from Effectus library. 6 ; 7 ;******************************************************** 8 9 10 ;Noname 11 ;651-655 028B-028F 12 ; 13 ;More spare bytes that you shouldn't use because future versions of the OS might use them. 14 ;Locations 651 and 652 are already used by version "B" as part of the interrupt handler routines. 15 16 ;OS registers we use as temporary: 17 ; 18 ;BUFRLO,BUFRHI 50,51 $32,$33 19 ;BFENLO,BFENHI 52,53 $34,$35 20 21 ;ADRESS 100,101 $64,$65 A temporary storage location used by the display handler for so many things that it made my mind spin and I forgot what they were. 22 ;MLTTMP 102,103 $66,$67 More temporary storage, with aliases OPNTMP and TOADR. 23 ;SAVADR 104,105 $68,$69 Also know as FRMADR. Also used for temporary storage. 24 ; Also not significant enough to explain (look at the OS listing if, for some reason, you really care). 25 26 ;Registers used when drawing line 27 ;ROWAC 112,113 $70,$71 28 ;COLAC 114,115 $72,$73 29 ;ENDPT 116,117 $74,$75 30 ;COUNTR 126,127 $7E,$7F COUNTR tells how many points have to be plotted before the line is finished. 31 32 = 0653 _putchr_proc_adr = $653 ;+$654 33 = 0032 ?argptr = $32 ;$33 34 = 0034 ?varptr = $34 35 = 0015 ?size = $15 ;15 //$16 BUFADR 36 = 0038 ?aux2 = $38 37 = 0039 ?aux = $39 38 39 ;Following assigns are defined by mc6502.atl 40 41 = 0032 _TW1 = $32 ;$33 mc6502.atl defines these labels as _TEMPW1, _TEMPW2. 42 = 0034 _TW2 = $34 ;$35 43 = 0015 _TW3 = $15 ;$16 44 = 0070 _TL1 = $70 ;four byte register ($70-$73) defined under name _TEMPL1 in mc6502.atl 45 46 = 0600 _stdbuf = $600 ;TODO: use LINBUF ($247-$26E) (100,101 can point to it) 47 48 ;Argument list: 49 ; 0 end of list 50 ; 1..127 Constant string 51 ; 128 EOL 52 ; 129 one byte integer reference 53 ; 130 two byte integer reference 54 ; 131 three byte integer eference 55 ; 132 four byte integer reference 56 57 417F _std_print_adr .proc 58 59 lda #<_adr_putchr 60 sta _putchr_proc_adr 61 lda #>_adr_putchr 62 sta _putchr_proc_adr+1 63 clc 64 bcc _std_print 65 .endp 66 67 417F _std_print_out .proc 68 417F-428C> A9 DF lda #<_out_putchr 69 4181 8D 53 06 sta _putchr_proc_adr 70 4184 A9 41 lda #>_out_putchr 71 4186 8D 54 06 sta _putchr_proc_adr+1 72 4189 18 clc ;TODO: No Jump, if we are directly before the _std_print 73 418A 90 00 bcc _std_print 74 .endp 75 76 418C _std_print .proc 77 78 ;Get address of argument from stack 79 418C 68 pla 80 418D 85 32 sta ?argptr 81 418F 68 pla 82 4190 85 33 sta ?argptr+1 83 4192 20 D0 41 jsr _read_byte ;just skip next byte (that is part of return address) 84 85 ;Read command from input 86 4195 command 87 4195 20 D0 41 jsr _read_byte 88 4198 85 15 sta ?size 89 419A A8 tay ; to set the flags 90 419B F0 2F beq done ;command 0 means end of sequence 91 419D 10 21 bpl str ;1..127 constant string 92 93 ;Write n-byte integer variable 94 95 419F 29 7F and #$7f 96 ; sec 97 ; sbc #128 98 41A1 85 15 sta ?size 99 41A3 F0 13 beq eol 100 101 41A5 20 D0 41 jsr _read_byte 102 41A8 85 34 sta ?varptr 103 41AA 20 D0 41 jsr _read_byte 104 41AD 85 35 sta ?varptr+1 105 106 41AF 20 34 42 jsr _std_bin_to_bcd 107 41B2 20 EA 41 jsr _std_print_hex 108 41B5 18 clc 109 41B6 90 DD bcc command ;jmp command 110 41B8 eol 111 41B8 A9 9B lda #155 112 41BA 20 DB 41 jsr _std_putchr 113 41BD 18 clc 114 41BE 90 D5 bcc command ;jmp command 115 ;Write constant string (size is 1..127, already stored) 116 117 41C0 str 118 41C0 20 D0 41 jsr _read_byte 119 41C3 20 DB 41 jsr _std_putchr 120 41C6 C6 15 dec ?size 121 41C8 D0 F6 bne str 122 41CA F0 C9 beq command 123 124 41CC done 125 41CC 6C 32 00 jmp (?argptr) 126 41CF 60 rts 127 128 41D0 _read_byte 129 41D0 A0 00 ldy #0 130 41D2 B1 32 lda (?argptr),y 131 41D4 E6 32 inc ?argptr 132 41D6 D0 02 bne skip 133 41D8 E6 33 inc ?argptr+1 134 41DA skip 135 41DA 60 rts 136 .endp 137 138 ;_std_eol .proc 139 ; lda #155 140 ;.endp 141 142 ;BEWARE!!! _std_eol continues directly to _std_putchr 143 144 41DB _std_putchr .proc 145 41DB 6C 53 06 jmp (_putchr_proc_adr) 146 41DE 60 rts 147 .endp 148 149 41DF _adr_putchr .proc 150 ;Write byte to address specified by _arr and increment the address by 1. 151 152 ;Convert ASCII to ATARI character screen code 153 ; 154 ;The rules are following: 155 ;0..31 +64 156 ;32..95 -32 157 ;96..127 0 (codes are same) 158 159 tax 160 rol 161 rol 162 rol 163 rol 164 and #3 165 tay 166 txa 167 eor tbl,y 168 169 ;write the char to specified address 170 ldy #0 171 sta (_arr),y 172 173 inc _arr 174 bne skip1 175 inc _arr+1 176 41DF skip1 177 rts 178 179 41DF tbl dta b(%01000000) ;%0 00 00000 00..31 +64 180 dta b(%00100000) ;%0 01 00000 32..63 -32 181 dta b(%01100000) ;%0 10 00000 64..95 -32 182 dta b(%00000000) ;%0 11 00000 96..127 0 183 184 .endp 185 186 41DF _out_putchr .proc 187 ;Write character from A to output. 188 189 41DF AA tax 190 41E0 AD 47 03 lda $347 ;ICPUTB+1 191 41E3 48 pha 192 41E4 AD 46 03 lda $346 ;ICPUTB 193 41E7 48 pha 194 41E8 8A txa 195 41E9 60 rts 196 197 .endp 198 199 41EA .proc _std_print_hex 200 ;Print hexadecimal number of arbitrary length (?size). 201 ;Leading zeroes are not printed. 202 ;In: 203 ; ?varptr Pointer to memory containing the number 204 ; ?size Number of bytes to print 205 ;Uses: 206 ; ?aux 207 ; ?aux2 208 209 41EA A5 15 lda ?size 210 41EC 85 39 sta ?aux 211 41EE A9 00 lda #0 212 41F0 85 38 sta ?aux2 ; number of non-zero digits on output 213 41F2 F0 12 beq _loop 214 41F4 _outbyte 215 41F4 A4 39 ldy ?aux 216 41F6 B1 34 lda (?varptr),y 217 41F8 48 pha 218 41F9 4A lsr 219 41FA 4A lsr 220 41FB 4A lsr 221 41FC 4A lsr 222 41FD 20 14 42 jsr _write_digit 223 224 4200 68 pla 225 4201 29 0F and #$0f 226 4203 20 14 42 jsr _write_digit 227 4206 _loop 228 4206 C6 39 dec ?aux 229 4208 10 EA bpl _outbyte 230 231 ;If no character has been written, write at least one 0 232 420A A5 38 lda ?aux2 233 420C D0 05 bne _no_empty 234 420E A9 30 lda #48 235 4210 20 DB 41 jsr _std_putchr 236 4213 _no_empty 237 238 4213 60 rts 239 240 4214 _write_digit 241 ;In: a 4 bit digit 242 243 4214 AA tax 244 4215 D0 04 bne _non_zero 245 4217 A5 38 lda ?aux2 246 4219 F0 08 beq _done ;this is zero and there has been no char before - no output 247 421B _non_zero 248 421B BD 24 42 lda hex,x 249 421E 20 DB 41 jsr _std_putchr 250 4221 E6 38 inc ?aux2 251 4223 _done 252 4223 60 rts 253 254 4224 30 31 32 33 34 35 + hex dta c"0123456789ABCDEF" 255 256 .endp 257 258 4234 .proc _std_bin_to_bcd 259 ;Convert binary number to BCD. 260 ;Arbitrary size (up to 127 bytes) are supported. 261 ;In: 262 ; ?varptr pointer to binary number 263 ; ?size number of bytes 264 ;Out: 265 ; ?size on output, returns size of resulting bcd number 266 ; ?varptr on output, containg pointer to converted BCD 267 ;Uses: 268 ; _stdbuf 269 ; ?aux 270 ; ?aux2 271 272 ;Compute size of resulting number 273 4234 A4 15 ldy ?size 274 4236 84 39 sty ?aux ; used to count later 275 4238 C8 iny ;add space to result 276 4239 84 15 sty ?size 277 278 ;Zero the destination buffer 279 423B A9 00 lda #0 280 423D 99 FF 05 zero sta _stdbuf-1,y 281 4240 88 dey 282 4241 D0 FA bne zero 283 284 ;**** We convert the number byte a time 285 4243 F8 sed 286 287 ;?aux = varptr(?aux) 288 4244 bytes 289 4244 C6 39 dec ?aux 290 4246 A4 39 ldy ?aux 291 4248 B1 34 lda (?varptr),y 292 424A 85 38 sta ?aux2 293 424C 38 sec ;set top bit to 1 294 424D B0 12 bcs loop 295 296 424F shift_byte 297 424F A2 00 ldx #0 298 4251 A4 15 ldy ?size 299 4253 bcd_mul2 300 4253 BD 00 06 lda _stdbuf,x 301 4256 7D 00 06 adc _stdbuf,x ;buf2(x) = buf2(x) * 2 + carry 302 4259 9D 00 06 sta _stdbuf,x 303 425C E8 inx 304 425D 88 dey 305 425E D0 F3 bne bcd_mul2 306 307 4260 18 clc 308 4261 26 38 loop rol ?aux2 ;divide by two, if result is 0, end 309 4263 D0 EA bne shift_byte 310 311 4265 A5 39 lda ?aux 312 4267 D0 DB bne bytes 313 4269 D8 cld 314 315 426A A9 00 lda #<_stdbuf 316 426C 85 34 sta ?varptr 317 426E A9 06 lda #>_stdbuf 318 4270 85 35 sta ?varptr+1 319 4272 60 rts 320 321 .endp 322 323 /* 324 Mul8 - 8-bit multiplication routine 325 326 Original source: 327 Book Atari Roots (Chapter Ten - Assembly Language Math) 328 Hyperlink: http://www.atariarchives.org/roots/chapter_10.php 329 330 Parameters: 331 a First multiplicant 332 x Second multiplicant 333 Result: 334 TEMPW2,TEMPW2+1 high byte of the result 335 */ 335 336 337 4273 _sys_mul8 .proc 338 339 = 0032 MUL1 = _TW1 340 = 0033 MUL2 = _TW1+1 341 = 0034 RES = _TW2 ;_TW2+1 342 343 4273 85 32 sta MUL1 ;input comes in A and X 344 4275 86 33 stx MUL2 345 346 4277 A9 00 lda #0 ;RES = 0 347 4279 85 34 sta RES 348 349 427B A2 08 ldx #8 350 427D loop 351 427D 46 32 lsr MUL1 ;MUL1 = MUL1 / 2 352 427F 90 03 bcc noadd 353 354 4281 18 clc ;RES = RES + (MUL2 * $ff) 355 4282 65 33 adc MUL2 356 4284 noadd 357 4284 6A ror @ ;RES = RES / 2 (Carry is 0, when there was no add) 358 4285 66 34 ror RES 359 360 4287 CA dex 361 4288 D0 F3 bne loop 362 363 428A 85 35 sta RES+1 364 428C 60 rts 365 366 .endp 367 368 /* 369 Mul16 - 16-bit multiplication routine 370 371 Parameters: 372 _TW1 First multiplicant (we use only two bytes now) 373 _TW2 Second multiplicant 374 Result: 375 _TL1 Result 376 */ 376 377 378 428D _sys_mul16 .proc 379 380 = 0032 MUL1 = _TW1 381 = 0034 MUL2 = _TW2 382 = 0070 RES = _TL1 383 384 lda #0 ;RES = 0; 385 sta RES 386 sta RES+1 387 sta RES+2 388 sta RES+3 389 390 ldx #16 391 428D loop 392 lsr MUL1+1 ;MUL1 = MUL1 / 2 393 ror MUL1 394 bcc noadd 395 396 lda RES+2 ;RES = RES + (MUL2 * $ffff) (only upper half) 397 clc 398 adc MUL2 399 sta RES+2 400 lda RES+3 401 adc MUL2+1 402 sta RES+3 403 428D noadd 404 ror RES+3 ;RES = RES / 2 (Carry is 0, when there was no add) 405 ror RES+2 406 ror RES+1 407 ror RES+0 408 409 dex 410 bne loop 411 412 rts 413 414 .endp 415 416 /* 417 Div8 - 8-bit division routine 418 419 Original source: 420 Book Atari Roots (Chapter Ten - Assembly Language Math) 421 Hyperlink: http://www.atariarchives.org/roots/chapter_10.php 422 423 Parameters: 424 _TEMPW1 16-bit dividend 425 a p1_math: 8-bit divisor 426 x number of bits of an divisir (8 max) 427 428 Result: 429 x STORE1: 8-bit quotient 430 a STORE2: 8-bit remainder 431 */ 431 432 433 428D _sys_div8 .proc 434 ldx #08 ; For an 8-bit divisor 435 436 428D _sys_div 437 438 = 0034 divisor = _TW2 439 = 0035 quotient = _TW2+1 440 441 sta divisor 442 lda #0 ; for non-8 divis 443 sta quotient 444 lda _TW1+1 445 sec 446 sbc divisor 447 428D dloop 448 php ; The loop that divides 449 rol quotient 450 asl _TW1 451 rol @ 452 plp 453 bcc addit 454 sbc divisor 455 jmp next 456 428D addit 457 adc divisor 458 428D next 459 dex 460 bne dloop 461 bcs fini 462 adc divisor 463 clc 464 428D fini 465 tax ; x = remainder 466 lda quotient ; a = quotient 467 rol 468 rts 469 470 .endp 471