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https://github.com/nim-lang/Nim.git
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89 lines
3.2 KiB
Nim
89 lines
3.2 KiB
Nim
const
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trailingZeros100: array[100, int8] = [2'i8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0,
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0, 0, 0, 0, 0, 0]
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digits100: array[200, char] = ['0', '0', '0', '1', '0', '2', '0', '3', '0', '4', '0', '5',
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'0', '6', '0', '7', '0', '8', '0', '9', '1', '0', '1', '1', '1', '2', '1', '3', '1', '4',
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'1', '5', '1', '6', '1', '7', '1', '8', '1', '9', '2', '0', '2', '1', '2', '2', '2', '3',
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'2', '4', '2', '5', '2', '6', '2', '7', '2', '8', '2', '9', '3', '0', '3', '1', '3', '2',
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'3', '3', '3', '4', '3', '5', '3', '6', '3', '7', '3', '8', '3', '9', '4', '0', '4', '1',
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'4', '2', '4', '3', '4', '4', '4', '5', '4', '6', '4', '7', '4', '8', '4', '9', '5', '0',
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'5', '1', '5', '2', '5', '3', '5', '4', '5', '5', '5', '6', '5', '7', '5', '8', '5', '9',
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'6', '0', '6', '1', '6', '2', '6', '3', '6', '4', '6', '5', '6', '6', '6', '7', '6', '8',
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'6', '9', '7', '0', '7', '1', '7', '2', '7', '3', '7', '4', '7', '5', '7', '6', '7', '7',
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'7', '8', '7', '9', '8', '0', '8', '1', '8', '2', '8', '3', '8', '4', '8', '5', '8', '6',
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'8', '7', '8', '8', '8', '9', '9', '0', '9', '1', '9', '2', '9', '3', '9', '4', '9', '5',
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'9', '6', '9', '7', '9', '8', '9', '9']
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# Inspired by https://engineering.fb.com/2013/03/15/developer-tools/three-optimization-tips-for-c
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# Generates:
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# .. code-block:: nim
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# var res = ""
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# for i in 0 .. 99:
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# if i < 10:
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# res.add "0" & $i
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# else:
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# res.add $i
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# doAssert res == digits100
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proc utoa2Digits*(buf: var openArray[char]; pos: int; digits: uint32) {.inline.} =
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assert(digits <= 99)
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buf[pos] = digits100[2 * digits]
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buf[pos+1] = digits100[2 * digits + 1]
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#copyMem(buf, unsafeAddr(digits100[2 * digits]), 2 * sizeof((char)))
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proc trailingZeros2Digits*(digits: uint32): int32 {.inline.} =
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assert(digits <= 99)
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return trailingZeros100[digits]
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func digits10*(num: uint64): int {.noinline.} =
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if num < 10'u64:
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result = 1
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elif num < 100'u64:
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result = 2
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elif num < 1_000'u64:
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result = 3
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elif num < 10_000'u64:
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result = 4
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elif num < 100_000'u64:
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result = 5
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elif num < 1_000_000'u64:
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result = 6
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elif num < 10_000_000'u64:
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result = 7
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elif num < 100_000_000'u64:
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result = 8
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elif num < 1_000_000_000'u64:
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result = 9
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elif num < 10_000_000_000'u64:
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result = 10
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elif num < 100_000_000_000'u64:
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result = 11
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elif num < 1_000_000_000_000'u64:
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result = 12
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else:
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result = 12 + digits10(num div 1_000_000_000_000'u64)
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template numToString*(result: var string, origin: uint64, length: int) =
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var num = origin
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var next = length - 1
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const nbatch = 100
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while num >= nbatch:
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let originNum = num
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num = num div nbatch
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let index = (originNum - num * nbatch) shl 1
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result[next] = digits100[index + 1]
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result[next - 1] = digits100[index]
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dec(next, 2)
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# process last 1-2 digits
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if num < 10:
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result[next] = chr(ord('0') + num)
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else:
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let index = num * 2
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result[next] = digits100[index + 1]
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result[next - 1] = digits100[index]
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