scsh-0.6/scsh/endian.scm.in

40 lines
1.3 KiB
Scheme

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