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math.bitwise: Add some more docs to find bits form >signed.

master
Doug Coleman 2020-04-26 23:49:17 -05:00
parent c21608b0a0
commit 94c6c8e5db
1 changed files with 20 additions and 4 deletions
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24
basis/math/bitwise/bitwise-docs.factor
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@ -41,13 +41,23 @@ HELP: bitfield
" } bitfield .b" " } bitfield .b"
"0b100100100100" "0b100100100100"
} }
} ; } ;
HELP: bits HELP: bits
{ $values { "m" integer } { "n" integer } { "m'" integer } } { $values { "m" integer } { "n" integer } { "m'" integer } }
{ $description "Keep only n bits from the integer m." } { $description "Keep only n bits from the integer m. For negative numbers, represent the number as two's complement (a positive integer representing a negative integer)." }
{ $example "USING: math.bitwise prettyprint ;" "0x123abcdef 16 bits .h" "0xcdef" } ; { $examples
{ $example
"USING: math.bitwise prettyprint ;"
"0x123abcdef 16 bits .h"
"0xcdef"
}
{ $example
"USING: math.bitwise prettyprint ;"
"-2 16 bits .h"
"0xfffe"
}
} ;
HELP: bit-range HELP: bit-range
{ $values { "x" integer } { "high" integer } { "low" integer } { "y" integer } } { $values { "x" integer } { "high" integer } { "low" integer } { "y" integer } }
@ -190,8 +200,14 @@ HELP: >signed
"0xff 8 >signed ." "0xff 8 >signed ."
"-1" "-1"
} }
{ $example "USING: math.bitwise prettyprint ;"
"0xf0 4 >signed ."
"0"
}
} }
{ $description "Interprets a number " { $snippet "x" } " as an " { $snippet "n" } "-bit number and converts it to a negative number " { $snippet "n" } "-bit number if the topmost bit is set." } ; { $description "Interprets a number " { $snippet "x" } " as an " { $snippet "n" } "-bit number and converts it to a negative number if the topmost bit is set." } ;
{ >signed bits } related-words
HELP: mask HELP: mask
{ $values { $values