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Simplify addInt, remove digits10 (#18356)

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* Simplify addInt, remove digits10

Co-authored-by: Charles Blake <charlechaud@gmail.com>

* Fix bootstrapping

* Add noInit to tmp array

* noInit -> noinit

Co-authored-by: Charles Blake <charlechaud@gmail.com>
This commit is contained in:
Clyybber
2021-06-28 15:00:14 +02:00
committed by GitHub
parent e720bbdd76
commit 6e74fecb42
4 changed files with 27 additions and 68 deletions
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58
lib/std/private/digitsutils.nim
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@@ -38,51 +38,39 @@ proc trailingZeros2Digits*(digits: uint32): int32 {.inline.} =
assert(digits <= 99)
return trailingZeros100[digits]
func digits10*(num: uint64): int {.noinline.} =
if num < 10'u64:
result = 1
elif num < 100'u64:
result = 2
elif num < 1_000'u64:
result = 3
elif num < 10_000'u64:
result = 4
elif num < 100_000'u64:
result = 5
elif num < 1_000_000'u64:
result = 6
elif num < 10_000_000'u64:
result = 7
elif num < 100_000_000'u64:
result = 8
elif num < 1_000_000_000'u64:
result = 9
elif num < 10_000_000_000'u64:
result = 10
elif num < 100_000_000_000'u64:
result = 11
elif num < 1_000_000_000_000'u64:
result = 12
else:
result = 12 + digits10(num div 1_000_000_000_000'u64)
template numToString*(result: var string, origin: uint64, length: int) =
func addIntImpl*(result: var string, origin: uint64) =
var tmp {.noinit.}: array[24, char]
var num = origin
var next = length - 1
var next = tmp.len - 1
const nbatch = 100
while num >= nbatch:
let originNum = num
num = num div nbatch
let index = (originNum - num * nbatch) shl 1
result[next] = digits100[index + 1]
result[next - 1] = digits100[index]
tmp[next] = digits100[index + 1]
tmp[next - 1] = digits100[index]
dec(next, 2)
# process last 1-2 digits
if num < 10:
result[next] = chr(ord('0') + num)
tmp[next] = chr(ord('0') + num)
else:
let index = num * 2
result[next] = digits100[index + 1]
result[next - 1] = digits100[index]
tmp[next] = digits100[index + 1]
tmp[next - 1] = digits100[index]
dec next
let n = result.len
let length = tmp.len - next
result.setLen n + length
when nimvm:
for i in 0..<length:
result[n+i] = tmp[next+i]
else:
when defined(js) or defined(nimscript):
for i in 0..<length:
result[n+i] = tmp[next+i]
else:
{.noSideEffect.}:
copyMem result[n].addr, tmp[next].addr, length