47 lines
1.5 KiB
Go
47 lines
1.5 KiB
Go
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// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module bits
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// --- RotateLeft ---
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// rotate_left_8 returns the value of x rotated left by (k mod 8) bits.
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// To rotate x right by k bits, call rotate_left_8(x, -k).
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//
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// This function's execution time does not depend on the inputs.
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pub fn rotate_left_8(x u8, k int) u8 {
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n := u8(8)
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s := u8(k) & u8(n - u8(1))
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return u8((x<<s) | (x>>(n-s)))
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}
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// rotate_left_16 returns the value of x rotated left by (k mod 16) bits.
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// To rotate x right by k bits, call rotate_left_16(x, -k).
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//
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// This function's execution time does not depend on the inputs.
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pub fn rotate_left_16(x u16, k int) u16 {
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n := u16(16)
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s := u16(k) & (n - u16(1))
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return u16((x<<s) | (x>>(n-s)))
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}
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// rotate_left_32 returns the value of x rotated left by (k mod 32) bits.
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// To rotate x right by k bits, call rotate_left_32(x, -k).
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//
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// This function's execution time does not depend on the inputs.
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pub fn rotate_left_32(x u32, k int) u32 {
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n := u32(32)
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s := u32(k) & (n - u32(1))
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return u32(u32(x<<s) | u32(x>>(n-s)))
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}
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// rotate_left_64 returns the value of x rotated left by (k mod 64) bits.
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// To rotate x right by k bits, call rotate_left_64(x, -k).
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//
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// This function's execution time does not depend on the inputs.
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pub fn rotate_left_64(x u64, k int) u64 {
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n := u64(64)
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s := u64(k) & (n - u64(1))
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return u64(u64(x<<s) | u64(x>>(n-s)))
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}
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