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#
#
# Nim's Runtime Library
# (c) Copyright 2015 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
# Page size of the system; in most cases 4096 bytes. For exotic OS or
# CPU this needs to be changed:
const
PageShift = when defined(nimPage256) or defined(cpu16): 3
elif defined(nimPage512): 9
elif defined(nimPage1k): 10
else: 12 # \ # my tests showed no improvements for using larger page sizes.
PageSize = 1 shl PageShift
PageMask = PageSize-1
MemAlign = # also minimal allocatable memory block
when defined(nimMemAlignTiny): 4
elif defined(useMalloc):
when defined(amd64): 16
else: 8
else: 16
BitsPerPage = PageSize div MemAlign
UnitsPerPage = BitsPerPage div (sizeof(int)*8)
# how many ints do we need to describe a page:
# on 32 bit systems this is only 16 (!)
TrunkShift = 9
BitsPerTrunk = 1 shl TrunkShift # needs to be power of 2 and divisible by 64
TrunkMask = BitsPerTrunk - 1
IntsPerTrunk = BitsPerTrunk div (sizeof(int)*8)
IntShift = 5 + ord(sizeof(int) == 8) # 5 or 6, depending on int width
IntMask = 1 shl IntShift - 1
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