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compile time toBytes

This commit is contained in:
andri lim 2019-10-08 20:40:27 +07:00 committed by zah
parent 21dc4c6519
commit 0b06077c55
1 changed files with 22 additions and 6 deletions
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28
stint/private/endians2_priv.nim
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@ -1,4 +1,4 @@
import ./bitops2_priv, ./datatypes
import ./bitops2_priv, ./datatypes, ./uint_bitwise_ops
import stew/endians2
export endians2
@ -9,13 +9,29 @@ func swapBytes*(x: UintImpl): UintImpl {.inline.} =
UintImpl(hi: hi, lo: lo)
func copyMem(x: UintImpl): auto {.compileTime.} =
const size = bitsof(x) div 8
var ret: array[size, byte]
type DT = type x.leastSignificantWord
for i in 0 ..< size:
let pos = i * 8
ret[i] = byte((x shr pos).leastSignificantWord and 0xFF.DT)
ret
func toBytes*(x: UintImpl, endian: Endianness = system.cpuEndian): auto {.inline.} =
# TODO can't use bitsof in return type (compiler bug?), hence return auto
# TODO compile-time version
var ret: array[bitsof(x) div 8, byte]
if endian == system.cpuEndian:
copyMem(addr ret[0], unsafeAddr x, ret.len)
when nimvm:
if endian == system.cpuEndian:
ret = copyMem(x)
else:
let v = swapBytes(x)
ret = copyMem(v)
else:
let v = swapBytes(x)
copyMem(addr ret[0], unsafeAddr v, ret.len)
if endian == system.cpuEndian:
copyMem(addr ret[0], unsafeAddr x, ret.len)
else:
let v = swapBytes(x)
copyMem(addr ret[0], unsafeAddr v, ret.len)
ret