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Fix doc of toInt/toUint + add more docs about undefined behaviours

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mratsim 2018-10-06 20:25:51 +02:00 committed by tersec
parent 7fa6329d4c
commit 7bbe7d8f9f
3 changed files with 10 additions and 4 deletions
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10
stint/io.nim
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@ -74,22 +74,24 @@ func to*(x: SomeUnsignedInt, T: typedesc[StUint]): T =
stuint(x, result.bits) stuint(x, result.bits)
func toInt*(num: Stint or StUint): int {.inline.}= func toInt*(num: Stint or StUint): int {.inline.}=
# Returns as int. Result is modulo 2^(sizeof(int) # Returns as int.
# Result is undefined if input does not fit in an int64
cast[int](num.data.least_significant_word) cast[int](num.data.least_significant_word)
func toUint*(num: Stint or StUint): uint {.inline.}= func toUint*(num: Stint or StUint): uint {.inline.}=
# Returns as int. Result is modulo 2^(sizeof(int) # Returns as uint. Result is modulo 2^(sizeof(uint))
num.data.least_significant_word num.data.least_significant_word
func toInt64*(num: Stint or StUint): int64 {.inline.}= func toInt64*(num: Stint or StUint): int64 {.inline.}=
# Returns as int64. Result is modulo 2^(sizeof(int) # Returns as int64.
# Result is undefined if input does not fit in an int64
when sizeof(uint) == 8: when sizeof(uint) == 8:
cast[int64](num.data.least_significant_word) cast[int64](num.data.least_significant_word)
else: else:
cast[int64](num.data.least_significant_two_words) cast[int64](num.data.least_significant_two_words)
func toUint64*(num: Stint or StUint): uint64 {.inline.}= func toUint64*(num: Stint or StUint): uint64 {.inline.}=
# Returns as int. Result is modulo 2^(sizeof(int) # Returns as uint64. Result is modulo 2^64.
when sizeof(uint) == 8: when sizeof(uint) == 8:
num.data.least_significant_word.uint64 num.data.least_significant_word.uint64
else: else:

2
stint/private/uint_bitwise_ops.nim
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@ -59,6 +59,8 @@ func `shl`*(x: UintImpl, y: SomeInteger): UintImpl {.inline.}=
func `shr`*(x: UintImpl, y: SomeInteger): UintImpl {.inline.}= func `shr`*(x: UintImpl, y: SomeInteger): UintImpl {.inline.}=
## Compute the `shift right` operation of x and y ## Compute the `shift right` operation of x and y
## Similar to C standard, result is undefined if y is bigger
## than the number of bits in x.
const halfSize: type(y) = getSize(x) div 2 const halfSize: type(y) = getSize(x) div 2
if y == 0: if y == 0:

2
stint/uint_public.nim
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@ -104,6 +104,8 @@ func `shr`*(x: StUint, y: SomeInteger): StUint {.inline.} =
result.data = x.data shr y result.data = x.data shr y
func `shl`*(x: StUint, y: SomeInteger): StUint {.inline.} = func `shl`*(x: StUint, y: SomeInteger): StUint {.inline.} =
## Logical shift right ## Logical shift right
## Similar to C standard, result is undefined if y is bigger
## than the number of bits in x.
result.data = x.data shl y result.data = x.data shl y
import ./private/uint_highlow import ./private/uint_highlow