Primes: n*2^m+1: Difference between revisions
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(Primes: n*2^m+1 in FreeBASIC) |
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</pre> |
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=={{header|PL/M}}== |
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{{works with|8080 PL/M Compiler}} ... under CP/M (or an emulator) |
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Interestingly, the primes up to m = 45 all have a single digit m and will all fit in 16 bits, which is handy as the 8080 PL/M compiler doesn't support integers larger than unsigned 16-bit. |
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<syntaxhighlight lang="plm"> |
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100H: /* FIND PRIMES OF THE FORM N * 2**M + 1 */ |
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DECLARE FALSE LITERALLY '0'; |
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DECLARE TRUE LITERALLY '0FFH'; |
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/* CP/M SYSTEM CALL AND I/O ROUTINES */ |
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BDOS: PROCEDURE( FN, ARG ); DECLARE FN BYTE, ARG ADDRESS; GOTO 5; END; |
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PR$CHAR: PROCEDURE( C ); DECLARE C BYTE; CALL BDOS( 2, C ); END; |
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PR$STRING: PROCEDURE( S ); DECLARE S ADDRESS; CALL BDOS( 9, S ); END; |
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PR$NL: PROCEDURE; CALL PR$CHAR( 0DH ); CALL PR$CHAR( 0AH ); END; |
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PR$NUMBER: PROCEDURE( N ); /* PRINTS A NUMBER IN THE MINIMUN FIELD WIDTH */ |
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DECLARE N ADDRESS; |
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DECLARE V ADDRESS, N$STR ( 6 )BYTE, W BYTE; |
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V = N; |
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W = LAST( N$STR ); |
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N$STR( W ) = '$'; |
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N$STR( W := W - 1 ) = '0' + ( V MOD 10 ); |
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DO WHILE( ( V := V / 10 ) > 0 ); |
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N$STR( W := W - 1 ) = '0' + ( V MOD 10 ); |
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END; |
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CALL PR$STRING( .N$STR( W ) ); |
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END PR$NUMBER; |
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/* END SYSTEM CALL AND I/O ROUTINES */ |
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/* SIEVE THE PRIMES TO 8000 */ |
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DECLARE PRIME ( 8001 )BYTE; |
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DO; |
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DECLARE ( I, S ) ADDRESS; |
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PRIME( 0 ), PRIME( 1 ) = FALSE; |
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PRIME( 2 ) = TRUE; |
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DO I = 3 TO LAST( PRIME ) BY 2; PRIME( I ) = TRUE; END; |
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DO I = 4 TO LAST( PRIME ) BY 2; PRIME( I ) = FALSE; END; |
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DO I = 3 TO LAST( PRIME ) / 2 BY 2; |
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IF PRIME( I ) THEN DO; |
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DO S = I * I TO LAST( PRIME ) BY I + I; PRIME( S ) = FALSE; END; |
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END; |
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END; |
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END; |
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DECLARE MAX$M LITERALLY '30'; /* MAXIMUM M WE WILL CONSIDER */ |
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/* FIND THE PRIMES */ |
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DECLARE ( N, M, P, TWO$TO$M ) ADDRESS; |
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DECLARE NOT$FOUND BYTE; |
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DO N = 1 TO 45; |
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M = 0; |
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TWO$TO$M = 1; |
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P = 0; |
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NOT$FOUND = 1; |
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DO WHILE M <= MAX$M |
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AND ( NOT$FOUND := NOT PRIME( P := ( N * TWO$TO$M ) + 1 ) ); |
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TWO$TO$M = TWO$TO$M + TWO$TO$M; |
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M = M + 1; |
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END; |
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CALL PR$CHAR( '(' ); |
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IF N < 10 THEN CALL PR$CHAR( ' ' ); |
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CALL PR$NUMBER( N ); |
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IF NOT$FOUND THEN DO; |
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CALL PR$STRING( .' NOT FOUND$' ); |
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END; |
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ELSE DO; |
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CALL PR$CHAR( ' ' ); |
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CALL PR$NUMBER( M ); |
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CALL PR$CHAR( ':' ); |
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CALL PR$CHAR( ' ' ); |
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IF P < 10 THEN CALL PR$CHAR( ' ' ); |
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IF P < 100 THEN CALL PR$CHAR( ' ' ); |
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IF P < 1000 THEN CALL PR$CHAR( ' ' ); |
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CALL PR$NUMBER( P ); |
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CALL PR$CHAR( ' ' ); |
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CALL PR$CHAR( ' ' ); |
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END; |
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CALL PR$CHAR( ')' ); |
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IF N MOD 5 = 0 THEN CALL PR$NL; |
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END; |
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EOF |
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</syntaxhighlight> |
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{{out}} |
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<pre> |
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( 1 0: 2 )( 2 0: 3 )( 3 1: 7 )( 4 0: 5 )( 5 1: 11 ) |
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( 6 0: 7 )( 7 2: 29 )( 8 1: 17 )( 9 1: 19 )(10 0: 11 ) |
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(11 1: 23 )(12 0: 13 )(13 2: 53 )(14 1: 29 )(15 1: 31 ) |
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(16 0: 17 )(17 3: 137 )(18 0: 19 )(19 6: 1217 )(20 1: 41 ) |
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(21 1: 43 )(22 0: 23 )(23 1: 47 )(24 2: 97 )(25 2: 101 ) |
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(26 1: 53 )(27 2: 109 )(28 0: 29 )(29 1: 59 )(30 0: 31 ) |
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(31 8: 7937 )(32 3: 257 )(33 1: 67 )(34 2: 137 )(35 1: 71 ) |
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(36 0: 37 )(37 2: 149 )(38 5: 1217 )(39 1: 79 )(40 0: 41 ) |
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(41 1: 83 )(42 0: 43 )(43 2: 173 )(44 1: 89 )(45 2: 181 ) |
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</pre> |
</pre> |
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