scsh-0.5/scsh/endian.scm.in

;;; 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@)