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60 lines
2.0 KiB
Nim
60 lines
2.0 KiB
Nim
#
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#
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# Nim's Runtime Library
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# (c) Copyright 2012 Andreas Rumpf
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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#
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## This module contains helpers that deal with different byte orders
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## (`endian`:idx:).
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proc swapEndian64*(outp, inp: pointer) =
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## copies `inp` to `outp` swapping bytes. Both buffers are supposed to
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## contain at least 8 bytes.
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var i = cast[cstring](inp)
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var o = cast[cstring](outp)
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o[0] = i[7]
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o[1] = i[6]
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o[2] = i[5]
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o[3] = i[4]
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o[4] = i[3]
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o[5] = i[2]
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o[6] = i[1]
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o[7] = i[0]
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proc swapEndian32*(outp, inp: pointer) =
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## copies `inp` to `outp` swapping bytes. Both buffers are supposed to
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## contain at least 4 bytes.
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var i = cast[cstring](inp)
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var o = cast[cstring](outp)
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o[0] = i[3]
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o[1] = i[2]
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o[2] = i[1]
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o[3] = i[0]
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proc swapEndian16*(outp, inp: pointer) =
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## copies `inp` to `outp` swapping bytes. Both buffers are supposed to
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## contain at least 2 bytes.
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var
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i = cast[cstring](inp)
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o = cast[cstring](outp)
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o[0] = i[1]
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o[1] = i[0]
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when system.cpuEndian == bigEndian:
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proc littleEndian64*(outp, inp: pointer) {.inline.} = swapEndian64(outp, inp)
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proc littleEndian32*(outp, inp: pointer) {.inline.} = swapEndian32(outp, inp)
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proc littleEndian16*(outp, inp: pointer) {.inline.} = swapEndian16(outp, inp)
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proc bigEndian64*(outp, inp: pointer) {.inline.} = copyMem(outp, inp, 8)
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proc bigEndian32*(outp, inp: pointer) {.inline.} = copyMem(outp, inp, 4)
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proc bigEndian16*(outp, inp: pointer) {.inline.} = copyMem(outp, inp, 2)
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else:
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proc littleEndian64*(outp, inp: pointer) {.inline.} = copyMem(outp, inp, 8)
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proc littleEndian32*(outp, inp: pointer) {.inline.} = copyMem(outp, inp, 4)
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proc littleEndian16*(outp, inp: pointer){.inline.} = copyMem(outp, inp, 2)
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proc bigEndian64*(outp, inp: pointer) {.inline.} = swapEndian64(outp, inp)
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proc bigEndian32*(outp, inp: pointer) {.inline.} = swapEndian32(outp, inp)
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proc bigEndian16*(outp, inp: pointer) {.inline.} = swapEndian16(outp, inp)
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