mirror of
https://github.com/bobbimanners/emailler.git
synced 2024-11-18 06:08:04 +00:00
72 lines
1.8 KiB
ArmAsm
72 lines
1.8 KiB
ArmAsm
; 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.inc"
|
|
|
|
.export timer_init
|
|
.export timer_read
|
|
.export timer_seconds
|
|
|
|
|
|
.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
|
|
|
|
timer_seconds:
|
|
lda #0
|
|
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 --
|