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Article contents:[[tags: egg]] == bitwise-utils [[toc:]] == Documentation Additional bitwise routines. === Usage <enscript language=scheme> (import bitwise-utils) </enscript> === logical-shift-left <procedure>(logical-shift-left N1 N2) -> integer</procedure> Returns left shift of {{N1}} by {{N2}} bits. ; {{N1}} : {{integer}} ; what to shift. ; {{N2}} : {{fixnum}} ; amount to shift. Aliases {{arithmetic-shift}}. === logical-shift-right <procedure>(logical-shift-right N1 N2) -> integer</procedure> Returns right shift of {{N1}} by {{N2}} bits. Sign preserving. ; {{N1}} : {{integer}} ; what to shift. ; {{N2}} : {{fixnum}} ; amount to shift. === arithmetic-shift-left <procedure>(arithmetic-shift-left N1 N2) -> integer</procedure> Returns left shift of {{N1}} by {{N2}} bits. ; {{N1}} : {{integer}} ; what to shift. ; {{N2}} : {{fixnum}} ; amount to shift. Aliases {{arithmetic-shift}}. === arithmetic-shift-right <procedure>(arithmetic-shift-right N1 N2) -> integer</procedure> Returns right shift of {{N1}} by {{N2}} bits. Sign extending. ; {{N1}} : {{integer}} ; what to shift. ; {{N2}} : {{fixnum}} ; amount to shift. Essentially {{(arithmetic-shift <> (- <>))}}. === bitwise-mask <procedure>(bitwise-mask WID [ON?]) -> integer</procedure> Returns {{WID}} low-order bits {{ON?}}. ; {{WID}} : {{fixnum}} ; mask bit width. ; {{ON?}} : {{boolean}} ; {{#t}} is {{#b1}}, {{#f}} is {{#b0}}; default {{#t}}. <enscript language=scheme> (bitwise-mask 5 #t) ;=> +0...011111 (#b+011111) (bitwise-mask 5 #f) ;=> -1...100000 (#b-100000) </enscript> === bitwise-join <procedure>(bitwise-join N0 [N1 ...]) -> integer</procedure> Returns adjoined bits. ; {{N0}} : {{integer}} ; seed. ; {{N1 ...}} : {{integer ...}} ; adjoins seed left-to-right. <enscript language=scheme> (bitwise-join #b10 #b0000001 #b101) ;=> #b101101 </enscript> === bitwise-split <procedure>(bitwise-split N WID) -> (list-of integer)</procedure> Returns {{N}} disjoined every {{WID}} bits. ; {{N}} : {{integer}} ; seed. ; {{WID}} : {{fixnum}} ; bit width. <enscript language=scheme> (bitwise-split #xabcdef 4) ;=> (#xa #xb #xc #xd #xe #xf) (bitwise-split #x-abcdef 4) ;=> (#x-a #x-b #x-c #x-d #x-e #x-f) </enscript> === bitwise-count <procedure>(bitwise-count N) -> fixnum</procedure> Returns number of set bits in {{N}}. ; {{N}} : {{integer}} === bitwise-merge <procedure>(bitwise-merge MASK N0 N1) -> integer</procedure> ; {{MASK}} : {{integer}} ; {{N0}} : {{integer}} ; {{N1}} : {{integer}} Renamed {{SRFI-60}} {{bitwise-if}}. === bitwise-nth? <procedure>(bitwise-nth? INDEX N) -> boolean</procedure> ; {{INDEX}} : {{integer}} ; {{N}} : {{fixnum}} Renamed {{SRFI-60}} {{bit-set?}}. === bitwise-any? <procedure>(bitwise-any? N1 N2) -> boolean</procedure> ; {{N1}} : {{integer}} ; {{N2}} : {{integer}} Renamed {{SRFI-60}} {{any-bits-set?}}. === bitwise-first-set <procedure>(bitwise-first-set N) -> fixnum</procedure> ; {{N}} :integer Renamed {{SRFI-60}} {{first-set-bit}}. === bitwise-reverse <procedure>(bitwise-reverse N K) -> integer</procedure> ; {{N}} :integer ; {{K}} :fixnum === bitwise-rotate <procedure>(bitwise-rotate K COUNT LEN) -> integer</procedure> Performs {{(bitwise-field-rotate K COUNT 0 LEN)}}. ; {{K}} : {{integer}} ; {{COUNT}} : {{fixnum}} ; {{LEN}} : {{fixnum}} === bitwise-set-nth <procedure>(bitwise-set-nth TO INDEX ON?) -> integer</procedure> ; {{TO}} : {{integer}} ; {{INDEX}} : {{fixnum}} ; {{ON?}} : {{boolean}} ; {{#t}} is {{#b1}}, {{#f}} is {{#b0}} Renamed {{SRFI-60}} {{(copy-bit k n b)}}; note argument order change. === bitwise-field <procedure>(bitwise-field N START END) -> integer</procedure> ; {{N}} : {{integer}} ; {{START}} : {{fixnum}} ; {{END}} : {{fixnum}} Renamed {{SRFI-60}} {{bit-field}}. === bitwise-field-copy <procedure>(bitwise-field-copy TO FROM START END) -> integer</procedure> ; {{TO}} : {{integer}} ; {{FROM}} : integer ; {{START}} : {{fixnum}} ; {{END}} : {{fixnum}} Renamed {{SRFI-60}} {{copy-bit-field}}. === bitwise-field-reverse <procedure>(bitwise-field-reverse N START END) -> integer</procedure> ; {{N}} : {{integer}} ; {{START}} : {{fixnum}} ; {{END}} : {{fixnum}} Renamed {{SRFI-60}} {{reverse-bit-field}}. <procedure>(bitwise-field-rotate N COUNT START END) -> integer</procedure> ; {{N}} : {{integer}} ; {{COUNT}} : {{fixnum}} ; {{START}} : {{fixnum}} ; {{END}} : {{fixnum}} Renamed {{SRFI-60}} {{rotate-bit-field}}. === number->boolean <procedure>(number->boolean NUM) -> boolean</procedure> {{0}} => {{#f}} & {{¬ 0}} => {{#t}}. === boolean->number <procedure>(boolean->number ANY) -> fixnum</procedure> {{#f}} => {{0}} & {{#t}} => {{1}}. === integer->list <procedure>(integer->list K [LEN]) -> (list-of boolean)</procedure> ; {{K}} : {{integer}} ; integer to represent as a bit list. ; {{LEN}} : {{fixnum}} ; number of bits, default is all bits. === list->integer <procedure>(list->integer BOOLS) -> integer</procedure> ; {{BOOLS}} : {{list}} ; treated as {{(list-of boolean-like)}} === bitwise-zeros <procedure>(bitwise-zeros N) -> integer</procedure> Return {{N}} zero bits. ; {{N}} : {{fixnum}} === bitwise-ones <procedure>(bitwise-ones N) -> integer</procedure> Return {{N}} one bits. ; {{N}} : {{fixnum}} === bitwise-abs <procedure>(bitwise-abs N) -> integer</procedure> Should {{N}} be negative {{bitwise-not}} the result. ; {{N}} : {{integer}} === bitwise-drop-right <procedure>(bitwise-drop-right N W) -> integer</procedure> ''Drop'' {{W}} right bits of {{N}}. ; {{N}} : {{integer}} ; {{W}} : {{fixnum}} === bitwise-cons <procedure>(bitwise-cons N M) -> integer</procedure> Concatenate {{N}} & {{M}}. ; {{N}} : {{integer}} ; {{M}} : {{integer}} == Requirements [[test]] [[test-utils]] == Author [[/users/kon-lovett|Kon Lovett]] == Repository This egg is hosted on the CHICKEN Subversion repository: [[https://anonymous@code.call-cc.org/svn/chicken-eggs/release/5/bitwise-utils|https://anonymous@code.call-cc.org/svn/chicken-eggs/release/5/bitwise-utils]] If you want to check out the source code repository of this egg and you are not familiar with Subversion, see [[/egg-svn-checkout|this page]]. == Version history ; 1.4.1 : Fix {{list->integer}} type regression. Fix {{boolean->number}} signature. ; 1.4.0 : Add {{}} & {{}}. Fix signatures (clean, not pure). ; 1.3.2 : Slight speed-up. ; 1.3.1 : New test-runner, add tests. ; 1.3.0 : Export useful helpers {{bitwise-zeros}}, {{bitwise-ones}}, {{bitwise-abs}}, {{bitwise-drop-right}}, & {{bitwise-cons}}. ; 1.2.2 : Fix {{bitwise->count}}. ; 1.2.2 : Fix {{integer->list}}/{{list->integer}} so invertible. ; 1.2.1 : . ; 1.2.0 : Remove {{srfi-60}} module. (Use {{srfi-60}} egg.) ; 1.1.4: Fix {{integer->list}} type. ; 1.1.3 : . ; 1.1.2 : . ; 1.1.1 : . ; 1.1.0 : Add {{srfi-60}} module. ; 1.0.1 : . ; 1.0.0 : Release. == License This code is in the public domain. Description of your changes:

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