mirror of
https://github.com/mgcaret/of816.git
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40 lines
1.2 KiB
Forth
40 lines
1.2 KiB
Forth
0 INVERT CONSTANT MAX-UINT
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0 INVERT 1 RSHIFT CONSTANT MAX-INT
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0 INVERT 1 RSHIFT INVERT CONSTANT MIN-INT
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0 INVERT 1 RSHIFT CONSTANT MID-UINT
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0 INVERT 1 RSHIFT INVERT CONSTANT MID-UINT+1
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: IFFLOORED
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[ -3 2 / -2 = INVERT ] LITERAL IF POSTPONE \ THEN ;
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: IFSYM
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[ -3 2 / -1 = INVERT ] LITERAL IF POSTPONE \ THEN ;
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\ THE SYSTEM MIGHT DO EITHER FLOORED OR SYMMETRIC DIVISION.
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\ SINCE WE HAVE ALREADY TESTED M*, FM/MOD, AND SM/REM WE CAN USE THEM IN TEST.
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IFFLOORED : T/MOD >R S>D R> FM/MOD ;
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IFFLOORED : T/ T/MOD SWAP DROP ;
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IFFLOORED : TMOD T/MOD DROP ;
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IFFLOORED : T*/MOD >R M* R> FM/MOD ;
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IFFLOORED : T*/ T*/MOD SWAP DROP ;
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IFSYM : T/MOD >R S>D R> SM/REM ;
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IFSYM : T/ T/MOD SWAP DROP ;
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IFSYM : TMOD T/MOD DROP ;
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IFSYM : T*/MOD >R M* R> SM/REM ;
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IFSYM : T*/ T*/MOD SWAP DROP ;
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0 CONSTANT 0S
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0 INVERT CONSTANT 1S
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T{ -> }T \ START WITH CLEAN SLATE
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( TEST IF ANY BITS ARE SET; ANSWER IN BASE 1 )
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T{ : BITSSET? IF 0 0 ELSE 0 THEN ; -> }T
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T{ 0 BITSSET? -> 0 }T ( ZERO IS ALL BITS CLEAR )
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T{ 1 BITSSET? -> 0 0 }T ( OTHER NUMBER HAVE AT LEAST ONE BIT )
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T{ -1 BITSSET? -> 0 0 }T
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( WE TRUST 1S, INVERT, AND BITSSET?; WE WILL CONFIRM RSHIFT LATER )
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1S 1 RSHIFT INVERT CONSTANT MSB
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T{ MSB BITSSET? -> 0 0 }T
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