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fix signed integer truncate for 32 bit platform

This commit is contained in:
jangko 2023-06-15 13:10:58 +07:00
parent 41bfed6bb7
commit c6422a9439
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GPG Key ID: 31702AE10541E6B9
1 changed files with 13 additions and 2 deletions
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13
stint/io.nim
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@ -65,6 +65,8 @@ func truncate*(num: StUint, T: typedesc[SomeInteger]): T {.inline.}=
## For unsigned result type, result is modulo 2^(sizeof T in bit)
## For signed result type, result is undefined if input does not fit in the target type.
result = T(num.leastSignificantWord())
when sizeof(T) > sizeof(Word):
result = result or (T(num.limbs[1]) shl WordBitWidth)
func truncate*(num: StInt, T: typedesc[SomeInteger]): T {.inline.}=
## Extract the int, uint, int8-int64 or uint8-uint64 portion of a multi-precision integer.
@ -80,11 +82,20 @@ func truncate*(num: StInt, T: typedesc[SomeInteger]): T {.inline.}=
if num.isNegative:
when T is SomeUnsignedInt:
doAssert(false, "cannot truncate negative number to unsigned integer")
else:
elif sizeof(T) <= sizeof(Word):
if n.leastSignificantWord() == Word(T.high) + 1:
result = low(T)
else:
result = -result
else:
if n == stint(T.high, num.bits) + 1'u:
result = low(T)
else:
#result = result or (T(num.limbs[1]) shl WordBitWidth)
result = -result
else:
when sizeof(T) > sizeof(Word):
result = result or (T(num.limbs[1]) shl WordBitWidth)
func stuint*(a: StUint, bits: static[int]): StUint[bits] {.inline.} =
## unsigned int to unsigned int conversion