50 lines
2.2 KiB
Factor
50 lines
2.2 KiB
Factor
! Copyright (C) 2009 John Benediktsson
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! See http://factorcode.org/license.txt for BSD license
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USING: help.syntax help.markup brainfuck strings ;
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IN: brainfuck
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HELP: run-brainfuck
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{ $values { "code" string } }
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{ $description
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"A brainfuck program is a sequence of eight commands that are "
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"executed sequentially. An instruction pointer begins at the first "
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"command, and each command is executed until the program terminates "
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"when the instruction pointer moves beyond the last command.\n"
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"\n"
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"The eight language commands, each consisting of a single character, "
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"are the following:\n"
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{ $table
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{ "Character" "Meaning" }
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{ ">" "increment the data pointer (to point to the next cell to the right)." }
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{ "<" "decrement the data pointer (to point to the next cell to the left)." }
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{ "+" "increment (increase by one) the byte at the data pointer." }
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{ "-" "decrement (decrease by one) the byte at the data pointer." }
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{ "." "output the value of the byte at the data pointer." }
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{ "," "accept one byte of input, storing its value in the byte at the data pointer." }
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{ "[" "if the byte at the data pointer is zero, then instead of moving the instruction pointer forward to the next command, jump it forward to the command after the matching ] command*." }
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{ "]" "if the byte at the data pointer is nonzero, then instead of moving the instruction pointer forward to the next command, jump it back to the command after the matching [ command*." }
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}
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"\n"
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"Brainfuck programs can be translated into C using the following "
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"substitutions, assuming ptr is of type unsigned char* and has been "
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"initialized to point to an array of zeroed bytes:\n"
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{ $table
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{ "Character" "C equivalent" }
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{ ">" "++ptr;" }
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{ "<" "--ptr;" }
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{ "+" "++*ptr;" }
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{ "-" "--*ptr;" }
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{ "." "putchar(*ptr);" }
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{ "," "*ptr=getchar();" }
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{ "[" "while (*ptr) {" }
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{ "]" "}" }
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}
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} ;
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HELP: get-brainfuck
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{ $values { "code" string } { "result" string } }
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{ $description "Returns the output from a brainfuck program as a result string." }
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{ $see-also run-brainfuck } ;
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