40 lines
1.2 KiB
Scheme
40 lines
1.2 KiB
Scheme
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;;; Endian routines for the Scheme Shell
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;;; Copyright (c) 1995 by Brian D. Carlstrom.
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;; Big Endian - Motorola, Sparc, HPPA, etc
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(define (net-to-host-32-big num32)
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(and (<= 0 num32 #xffffffff)
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num32))
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(define (net-to-host-16-big num16)
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(and (<= 0 num16 #xffffffff)
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num16))
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;; Little Endian - Intel, Vax, Alpha
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(define (net-to-host-32-little num32)
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(and (<= 0 num32 #xffffffff)
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(let* ((num24 (arithmetic-shift num32 -8))
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(num16 (arithmetic-shift num24 -8))
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(num08 (arithmetic-shift num16 -8))
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(byte0 (bitwise-and #b11111111 num08))
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(byte1 (bitwise-and #b11111111 num16))
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(byte2 (bitwise-and #b11111111 num24))
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(byte3 (bitwise-and #b11111111 num32)))
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(+ (arithmetic-shift byte3 24)
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(arithmetic-shift byte2 16)
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(arithmetic-shift byte1 8)
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byte0))))
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(define (net-to-host-16-little num16)
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(and (<= 0 num16 #xffffffff)
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(let* ((num08 (arithmetic-shift num16 -8))
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(byte0 (bitwise-and #b11111111 num08))
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(byte1 (bitwise-and #b11111111 num16)))
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(+ (arithmetic-shift byte1 8)
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byte0))))
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(define net-to-host-32 net-to-host-32-big)
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(define net-to-host-16 net-to-host-16-big)
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(define host-to-net-32 net-to-host-32-big)
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(define host-to-net-16 net-to-host-16-big)
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