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refactor hash in JS backend #16863

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merged 6 commits into from
Jan 30, 2021
Merged

refactor hash in JS backend #16863

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459f3cd
refactor hash in JS backend
ringabout Jan 29, 2021
7b02fa6
fix
ringabout Jan 30, 2021
f9d5331
fix
ringabout Jan 30, 2021
fc0a32f
fix
ringabout Jan 30, 2021
c37b7d0
inline'
ringabout Jan 30, 2021
3abe68f
fix
ringabout Jan 30, 2021
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28 changes: 14 additions & 14 deletions lib/pure/hashes.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -127,26 +127,26 @@ when defined(js):
import std/jsbigints
import std/private/jsutils

proc noBigInt(): bool =
asm """`result` = typeof BigInt == 'undefined'"""

proc hiXorLoJs(a, b: JsBigInt): JsBigInt =
let prod = a * b
let mask = (big"1" shl big"64") - big"1"
let
prod = a * b
mask = big"0xffffffffffffffff" # mask = (big"1" shl big"64") - big"1"
result = (prod shr big"64") xor (prod and mask)

template hashWangYiJS(x: JsBigInt): Hash =
let P0 = (big"0xa0761d64" shl big"32") or big"0x78bd642f"
let P1 = (big"0xe7037ed1" shl big"32") or big"0xa0b428db"
let P58 = (big"0xeb44acca" shl big"32") or (big"0xb455d165" xor big"8")
let res = hiXorLoJs(hiXorLoJs(P0, x xor P1), P58)
let maxSafeInterger = (big"1" shl big"53") - big"1"
let
P0 = big"0xa0761d6478bd642f"
P1 = big"0xe7037ed1a0b428db"
P58 = big"0xeb44accab455d165" xor big"8"
res = hiXorLoJs(hiXorLoJs(P0, x xor P1), P58)
maxSafeInterger = (big"1" shl big"53") - big"1"
cast[Hash](toNumber((res and maxSafeInterger))) and cast[Hash](0xFFFFFFFF)

template asBigInt(x: float): JsBigInt =
let buffer = newArrayBuffer(8)
let floatBuffer = newFloat64Array(buffer)
let uintBuffer = newBigUint64Array(buffer)
let
buffer = newArrayBuffer(8)
floatBuffer = newFloat64Array(buffer)
uintBuffer = newBigUint64Array(buffer)
floatBuffer[0] = x
uintBuffer[0]

Expand All @@ -166,7 +166,7 @@ proc hashWangYi1*(x: int64|uint64|Hash): Hash {.inline.} =
result = cast[Hash](h(x))
else:
when defined(js):
if noBigInt():
if hasJsBigInt():
result = cast[Hash](x) and cast[Hash](0xFFFFFFFF)
else:
result = hashWangYiJS(big(x))
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3 changes: 3 additions & 0 deletions lib/std/private/jsutils.nim
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Expand Up @@ -15,3 +15,6 @@ when defined(js):
func `[]`*(arr: Uint32Array, i: int): uint32 {.importjs: "#[#]".}
func `[]`*(arr: BigUint64Array, i: int): JsBigInt {.importjs: "#[#]".}
func `[]=`*(arr: Float64Array, i: int, v: float) {.importjs: "#[#] = #".}

proc hasJsBigInt*(): bool =
asm """`result` = typeof BigInt == 'undefined'"""