freebsd-dev/sys/boot/forth/delay.4th

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\ Copyright (c) 2008-2015 Devin Teske <dteske@FreeBSD.org>
\ All rights reserved.
\
\ Redistribution and use in source and binary forms, with or without
\ modification, are permitted provided that the following conditions
\ are met:
\ 1. Redistributions of source code must retain the above copyright
\ notice, this list of conditions and the following disclaimer.
\ 2. Redistributions in binary form must reproduce the above copyright
\ notice, this list of conditions and the following disclaimer in the
\ documentation and/or other materials provided with the distribution.
\
\ THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
\ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
\ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
\ ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
\ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
\ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
\ OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
\ HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
\ LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
\ OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
\ SUCH DAMAGE.
\
\ $FreeBSD$
marker task-delay.4th
vocabulary delay-processing
only forth also delay-processing definitions
2 constant delay_default \ Default delay (in seconds)
3 constant etx_key \ End-of-Text character produced by Ctrl+C
13 constant enter_key \ Carriage-Return character produce by ENTER
27 constant esc_key \ Escape character produced by ESC or Ctrl+[
variable delay_tstart \ state variable used for delay timing
variable delay_delay \ determined configurable delay duration
variable delay_cancelled \ state variable for user cancellation
variable delay_showdots \ whether continually print dots while waiting
only forth definitions also delay-processing
: delay_execute ( -- )
\ make sure that we have a command to execute
s" delay_command" getenv dup -1 = if
drop exit
then
\ read custom time-duration (if set)
s" loader_delay" getenv dup -1 = if
drop \ no custom duration (remove dup'd bunk -1)
delay_default \ use default setting (replacing bunk -1)
else
\ make sure custom duration is a number
?number 0= if
delay_default \ use default if otherwise
then
then
\ initialize state variables
delay_delay ! \ stored value is on the stack from above
seconds delay_tstart ! \ store the time we started
0 delay_cancelled ! \ boolean flag indicating user-cancelled event
false delay_showdots ! \ reset to zero and read from environment
s" delay_showdots" getenv dup -1 <> if
2drop \ don't need the value, just existance
true delay_showdots !
else
drop
then
\ Loop until we have exceeded the desired time duration
begin
25 ms \ sleep for 25 milliseconds (40 iterations/sec)
\ throw some dots up on the screen if desired
delay_showdots @ if
." ." \ dots visually aid in the perception of time
then
\ was a key depressed?
key? if
key \ obtain ASCII value for keystroke
dup enter_key = if
-1 delay_delay ! \ break loop
then
dup etx_key = swap esc_key = OR if
-1 delay_delay ! \ break loop
-1 delay_cancelled ! \ set cancelled flag
then
then
\ if the time duration is set to zero, loop forever
\ waiting for either ENTER or Ctrl-C/Escape to be pressed
delay_delay @ 0> if
\ calculate elapsed time
seconds delay_tstart @ - delay_delay @ >
else
-1 \ break loop
then
until
\ if we were throwing up dots, throw up a line-break
delay_showdots @ if
cr
then
\ did the user press either Ctrl-C or Escape?
delay_cancelled @ if
2drop \ we don't need the command string anymore
else
evaluate \ evaluate/execute the command string
then
;
only forth definitions