application/octet-stream
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2.72 KB
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;;; Nujel - Copyright (C) 2020-2021 - Benjamin Vincent Schulenburg
;;; This project uses the MIT license, a copy should be included under /LICENSE
;;;
;;; Some functions manipulating binary date
[defn bit-shift-right [cur-val shift-amount]
"Shift all the bits in cur-val to the right by shift-amount"
""
"cur-val: The integer val whose bits we want to shift"
"shift-amount: The amount of digits we want to shift the value by"
""
"A shifted integer"
[deftest 0 [bit-shift-right 16 8]]
[deftest 1 [bit-shift-right 16 4]]
[deftest 16 [bit-shift-right 16 0]]
:cat :bitwise-operations
[bit-shift-left cur-val [- shift-amount]]]
[defn bit-test? [test-val bit-pos]
"Test bit at position i"
""
"We check if test-val has a 1 at bit-pos and return #t if that is the case"
""
"test-val: The integer in which to look for the bit"
"bit-pos: Which bit to look for, with 0 being the least significant digit"
""
"A boolean signifying whether the bit is set or not"
[deftest #t [bit-test? #b1001 0]]
[deftest #f [bit-test? #b1001 1]]
[deftest #f [bit-test? #b1001 7]]
:cat :bitwise-operations
[typecheck/only test-val :int]
[typecheck/only bit-pos :int]
[not [zero? [bit-and test-val [bit-shift-left 1 bit-pos]]]]]
[defn bit-set [cur-val bit-pos]
"Set bit-pos within cur-val to 1"
""
"cur-val: The integer where we set the bit in"
"bit-pos: The index of the bit we want to change, with 0 being the least significant digit"
""
"An integer cur-val but with a guaranteed 1 at bit-pos"
[deftest #b1111 [bit-set #b1011 2]]
:cat :bitwise-operations
[bit-or cur-val [bit-shift-left 1 bit-pos]]]
[defn bit-flip [cur-val bit-pos]
"Flip the bit at bit-pos within cur-val"
""
"cur-val: The integer where we flip the bit in"
"bit-pos: The index of the bit we want to flip, with 0 being the least significant digit"
""
"An integer cur-val but with the bit at position bit-pos flipped"
:cat :bitwise-operations
[deftest #b1111 [bit-flip #b1011 2]]
[deftest #b1011 [bit-flip #b1111 2]]
[bit-xor cur-val [bit-shift-left 1 bit-pos]]]
[defn bit-clear [cur-val bit-pos]
"Clear the bit at bit-pos within cur-val"
""
"cur-val: The integer where we clear the bit in"
"bit-pos: The index of the bit we want to clear, with 0 being the least significant digit"
""
"An integer cur-val but with the bit at position bit-pos forced to 0"
:cat :bitwise-operations
[deftest #b1001 [bit-clear #b1011 1]]
[deftest #b1011 [bit-clear #b1011 2]]
[bit-and cur-val [bit-not [bit-shift-left 1 bit-pos]]]]
