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* Enable customizing PageSize (via PageShift). This enables adjusting PageSize for embedded targets without abusing cpu16. * copy nimPageXYZ settings for mmpaptest * add docs for Nim manual * add docs for Nim manual * docs tweaks Co-authored-by: Jaremy Creechley <jaremy.creechley@panthalassa.com>
37 lines
1.2 KiB
Nim
37 lines
1.2 KiB
Nim
# Small test program to test for mmap() weirdnesses
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import system/ansi_c
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import posix
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proc osAllocPages(size: int): pointer {.inline.} =
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result = mmap(nil, size, PROT_READ or PROT_WRITE,
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MAP_PRIVATE or MAP_ANONYMOUS, -1, 0)
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if result == nil or result == cast[pointer](-1):
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quit 1
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cfprintf(c_stdout, "allocated pages %p..%p\n", result,
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cast[int](result) + size)
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proc osDeallocPages(p: pointer, size: int) {.inline} =
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cfprintf(c_stdout, "freed pages %p..%p\n", p, cast[int](p) + size)
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discard munmap(p, size-1)
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proc `+!!`(p: pointer, size: int): pointer {.inline.} =
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result = cast[pointer](cast[int](p) + size)
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const
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PageShift = when defined(nimPage256) or defined(cpu16): 8
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elif defined(nimPage512): 9
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elif defined(nimPage1k): 10
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else: 12 # \ # my tests showed no improvements for using larger page sizes.
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PageSize = 1 shl PageShift
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var p = osAllocPages(3 * PageSize)
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osDeallocPages(p, PageSize)
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# If this fails the OS has freed the whole block starting at 'p':
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echo(cast[ptr int](p +!! (PageSize*2))[])
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osDeallocPages(p +!! PageSize*2, PageSize)
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osDeallocPages(p +!! PageSize, PageSize)
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