mirror of
https://github.com/bobbimanners/emailler.git
synced 2024-11-18 06:08:04 +00:00
80 lines
3.0 KiB
HTML
80 lines
3.0 KiB
HTML
|
<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/><link rel="stylesheet" type="text/css" href="ca65-doc-style.css"/></head><body><a href="ref_index.html"><h1>ip65 technical reference</h1></a><h1>File : drivers/a2timer.s</h1><pre> timer routines
|
||
|
|
|
||
|
|
unfortunately the standard Apple 2 has no CIA or VBI, so for the moment, we will
|
||
|
|
make each call to 'timer_read' delay for a little while
|
||
|
|
this kludge will make the polling loops work at least
|
||
|
|
|
||
|
|
timer_read is meant to return a counter with millisecond resolution
|
||
|
|
</pre><h2 id="functions">functions</h2><table><tr><th>function</th><th>description</th></tr><tr><td id="timer_init">timer_init</td><td><pre>reset timer to 0
|
||
|
|
inputs: none
|
||
|
|
outputs: none
</pre></td></tr><tr><td id="timer_read">timer_read</td><td><pre>this SHOULD just read the current timer value
|
||
|
|
but since a standard apple 2 has no dedicated timing circuit,
|
||
|
|
each call to this function actually delays a while, then updates the current value
|
||
|
|
inputs: none
|
||
|
|
outputs: AX = current timer value (roughly equal to number of milliseconds since the last call to 'timer_init')
</pre></td></tr></table><h2>implementation</h2><pre id="code">; timer routines
|
||
|
|
;
|
||
|
|
; unfortunately the standard Apple 2 has no CIA or VBI, so for the moment, we will
|
||
|
|
; make each call to 'timer_read' delay for a little while
|
||
|
|
; this kludge will make the polling loops work at least
|
||
|
|
;
|
||
|
|
; timer_read is meant to return a counter with millisecond resolution
|
||
|
|
|
||
|
|
.include "../inc/common.i"
|
||
|
|
|
||
|
|
|
||
|
|
.export timer_init
|
||
|
|
.export timer_read
|
||
|
|
|
||
|
|
.bss
|
||
|
|
current_time_value: .res 2
|
||
|
|
|
||
|
|
.code
|
||
|
|
|
||
|
|
;reset timer to 0
|
||
|
|
;inputs: none
|
||
|
|
;outputs: none
|
||
|
|
timer_init:
|
||
|
|
ldax #0
|
||
|
|
stax current_time_value
|
||
|
|
rts
|
||
|
|
|
||
|
|
;this SHOULD just read the current timer value
|
||
|
|
;but since a standard apple 2 has no dedicated timing circuit,
|
||
|
|
;each call to this function actually delays a while, then updates the current value
|
||
|
|
; inputs: none
|
||
|
|
; outputs: AX = current timer value (roughly equal to number of milliseconds since the last call to 'timer_init')
|
||
|
|
timer_read:
|
||
|
|
lda #111
|
||
|
|
jsr $fca8 ;wait for about 33ms
|
||
|
|
clc
|
||
|
|
lda #33
|
||
|
|
adc current_time_value
|
||
|
|
sta current_time_value
|
||
|
|
bcc :+
|
||
|
|
inc current_time_value+1
|
||
|
|
:
|
||
|
|
ldax current_time_value
|
||
|
|
rts
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
;-- LICENSE FOR a2timer.s --
|
||
|
|
; The contents of this file are subject to the Mozilla Public License
|
||
|
|
; Version 1.1 (the "License"); you may not use this file except in
|
||
|
|
; compliance with the License. You may obtain a copy of the License at
|
||
|
|
; http://www.mozilla.org/MPL/
|
||
|
|
;
|
||
|
|
; Software distributed under the License is distributed on an "AS IS"
|
||
|
|
; basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
|
||
|
|
; License for the specific language governing rights and limitations
|
||
|
|
; under the License.
|
||
|
|
;
|
||
|
|
; The Original Code is ip65.
|
||
|
|
;
|
||
|
|
; The Initial Developer of the Original Code is Jonno Downes,
|
||
|
|
; jonno@jamtronix.com.
|
||
|
|
; Portions created by the Initial Developer are Copyright (C) 2009
|
||
|
|
; Jonno Downes. All Rights Reserved.
|
||
|
|
; -- LICENSE END --
|
||
|
|
</pre></body></html>
|