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more memory-efficient implementation of line reading

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This commit is contained in:
Shivaram Lingamneni 2020-08-07 01:10:46 -04:00
parent 12bcba01cd
commit c78253fd93
6 changed files with 96 additions and 45 deletions
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16
irc/utils/math.go Normal file
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// Copyright (c) 2020 Shivaram Lingamneni <slingamn@cs.stanford.edu>
// released under the MIT license
package utils
// return n such that v <= n and n == 2**i for some i
func RoundUpToPowerOfTwo(v int) int {
// http://graphics.stanford.edu/~seander/bithacks.html
v -= 1
v |= v >> 1
v |= v >> 2
v |= v >> 4
v |= v >> 8
v |= v >> 16
return v + 1
}

19
irc/utils/math_test.go Normal file
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// Copyright (c) 2020 Shivaram Lingamneni <slingamn@cs.stanford.edu>
// released under the MIT license
package utils
import (
"testing"
)
func TestRoundUp(t *testing.T) {
assertEqual(RoundUpToPowerOfTwo(2), 2, t)
assertEqual(RoundUpToPowerOfTwo(3), 4, t)
assertEqual(RoundUpToPowerOfTwo(64), 64, t)
assertEqual(RoundUpToPowerOfTwo(65), 128, t)
assertEqual(RoundUpToPowerOfTwo(100), 128, t)
assertEqual(RoundUpToPowerOfTwo(1000), 1024, t)
assertEqual(RoundUpToPowerOfTwo(1025), 2048, t)
assertEqual(RoundUpToPowerOfTwo(269435457), 536870912, t)
}