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Unify initBigInt for SomeIntegers #142

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Unify initBigInt for SomeIntegers #142

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55 changes: 24 additions & 31 deletions src/bigints.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -37,39 +37,32 @@ func initBigInt*(vals: sink seq[uint32], isNegative = false): BigInt =
result.isNegative = isNegative
normalize(result)

func initBigInt*[T: int8|int16|int32](val: T): BigInt =
if val < 0:
result.limbs = @[(not val).uint32 + 1] # manual 2's complement (to avoid overflow)
result.isNegative = true
else:
func initBigInt*[T: SomeInteger](val: T): BigInt =
when T is int8 | int16 | int32 or (T is int and sizeof(int) <= 4):
if val < 0:
result.limbs = @[(not val).uint32 + 1] # manual 2's complement (to avoid overflow)
result.isNegative = true
else:
result.limbs = @[val.uint32]
result.isNegative = false
elif T is uint8 | uint16 | uint32 or (T is uint and sizeof(int) <= 4):
result.limbs = @[val.uint32]
result.isNegative = false

func initBigInt*[T: uint8|uint16|uint32](val: T): BigInt =
result.limbs = @[val.uint32]

func initBigInt*(val: int64): BigInt =
var a = val.uint64
if val < 0:
a = not a + 1 # 2's complement
result.isNegative = true
if a > uint32.high:
result.limbs = @[(a and uint32.high).uint32, (a shr 32).uint32]
else:
result.limbs = @[a.uint32]

func initBigInt*(val: uint64): BigInt =
if val > uint32.high:
result.limbs = @[(val and uint32.high).uint32, (val shr 32).uint32]
elif T is int64 | int:
var a = val.uint64
if val < 0:
a = not a + 1 # 2's complement
result.isNegative = true
if a > uint32.high:
result.limbs = @[(a and uint32.high).uint32, (a shr 32).uint32]
else:
result.limbs = @[a.uint32]
elif T is uint64 | uint:
if val > uint32.high:
result.limbs = @[(val and uint32.high).uint32, (val shr 32).uint32]
else:
result.limbs = @[val.uint32]
else:
result.limbs = @[val.uint32]

when sizeof(int) == 4:
template initBigInt*(val: int): BigInt = initBigInt(val.int32)
template initBigInt*(val: uint): BigInt = initBigInt(val.uint32)
else:
template initBigInt*(val: int): BigInt = initBigInt(val.int64)
template initBigInt*(val: uint): BigInt = initBigInt(val.uint64)
{.error: "unsupported integer type".}

func initBigInt*(val: BigInt): BigInt =
result = val
Expand Down