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# -*- tcl -*-
# # ## ### ##### ######## #############
# (C) 2009 Andreas Kupries
# @@ Meta Begin
# Package tcl::chan::random 1.1
# Meta as::author {Andreas Kupries}
# Meta as::copyright 2009
# Meta as::license BSD
# Meta description Implementation of a channel similar to
# Meta description Memchan's random channel. Based on Tcl
# Meta description 8.5's channel reflection support. Exports
# Meta description a single command for the creation of new
# Meta description channels. One argument, a list of
# Meta description numbers to initialize the feedback
# Meta description register of the internal random number
# Meta description generator. Result is the handle of the
# Meta description new channel.
# Meta platform tcl
# Meta require TclOO
# Meta require tcl::chan::events
# Meta require {Tcl 8.5}
# @@ Meta End
# # ## ### ##### ######## #############
package require tcl::chan::events
package require Tcl 8.5 9
package require TclOO
# # ## ### ##### ######## #############
namespace eval ::tcl::chan {}
proc ::tcl::chan::random {seed} {
return [::chan create {read} [random::implementation new $seed]]
}
oo::class create ::tcl::chan::random::implementation {
superclass tcl::chan::events ; # -> initialize, finalize, watch
constructor {theseed} {
my variable seed next
set seed $theseed
set next [expr "([join $seed +]) & 0xff"]
next
}
method initialize {args} {
my allow read
next {*}$args
}
# Generate and return a block of N randomly selected bytes, as
# requested. Random device.
method read {c n} {
set buffer {}
while {$n} {
append buffer [binary format c [my Next]]
incr n -1
}
return $buffer
}
variable seed
variable next
method Next {} {
my variable seed next
set result $next
set next [expr {(2*$next - [lindex $seed 0]) & 0xff}]
set seed [linsert [lrange $seed 1 end] end $result]
return $result
}
}
# # ## ### ##### ######## #############
package provide tcl::chan::random 1.1
return
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