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math.bitwise: Fix shift "right" to shift "left" for bitfield. 

This word was really hard to understand so I reworked the docs and added another example.
master
Doug Coleman 2020-04-18 19:46:29 -05:00
parent 8d4f0be202
commit e6b546c358
1 changed files with 17 additions and 5 deletions
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22
basis/math/bitwise/bitwise-docs.factor
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@ -4,12 +4,12 @@ USING: assocs help.markup help.syntax math sequences kernel ;
IN: math.bitwise
HELP: bitfield
{ $values { "values..." "a series of objects" } { "bitspec" "an array" } { "n" integer } }
{ $description "Constructs an integer from a series of values on the stack together with a bit field specifier, which is an array whose elements have one of the following shapes:"
{ $values { "values..." "a series of objects on the stack" } { "bitspec" "an array" } { "n" integer } }
{ $description "Constructs an integer (bit field) from a series of values on the stack together with a bit field specifier, which is an array whose elements have one of the following shapes:"
{ $list
{ { $snippet "{ constant shift }" } " - the resulting bit field is bitwise or'd with " { $snippet "constant" } " shifted to the right by " { $snippet "shift" } " bits" }
{ { $snippet "{ word shift }" } " - the resulting bit field is bitwise or'd with " { $snippet "word" } " applied to the top of the stack; the result is shifted to the right by " { $snippet "shift" } " bits" }
{ { $snippet "shift" } " - the resulting bit field is bitwise or'd with the top of the stack; the result is shifted to the right by " { $snippet "shift" } " bits" }
{ { $snippet "{ word shift }" } " - " { $snippet "word" } " is applied to the top of the stack and the result is shifted to the left by " { $snippet "shift" } " bits and bitor'd with the bit field" }
{ { $snippet "shift" } " - the top of the stack is shifted to the left by " { $snippet "shift" } " bits and bitor'd with the bit field" }
{ { $snippet "{ constant shift }" } " - " { $snippet "constant" } " is shifted to the left by " { $snippet "shift" } " bits and bitor'd with the bit field" }
}
"The bit field specifier is processed left to right, so stack values should be supplied in reverse order." }
{ $examples
@ -30,6 +30,18 @@ HELP: bitfield
" 0"
" } bitfield ;"
}
"Square the 3 from the stack and shift 8, place the 1 from the stack at bit 5, and shift a constant 1 to bit 2:"
{ $example
"USING: math math.bitwise prettyprint ;"
"1 3"
" {"
" { sq 8 }"
" 5"
" { 1 2 }"
" } bitfield .b"
"0b100100100100"
}
} ;
HELP: bits