mirror of
https://github.com/cc65/cc65.git
synced 2024-12-24 11:31:31 +00:00
419eb700b5
The way we want to use the INITBSS segment - and especially the fact that it won't have the type bss on all ROM based targets - means that the name INITBSS is misleading. After all INIT is the best name from my perspective as it serves several purposes and therefore needs a rather generic name. Unfortunately this means that the current INIT segment needs to be renamed too. Looking for a short (ideally 4 letter) name I came up with ONCE as it contains all code (and data) accessed only once during initialization.
92 lines
2.3 KiB
ArmAsm
92 lines
2.3 KiB
ArmAsm
;
|
|
; 2003-04-13, Ullrich von Bassewitz
|
|
; 2012-02-06, Greg King
|
|
;
|
|
; #include <time.h>
|
|
;
|
|
; typedef unsigned long int clock_t;
|
|
; clock_t _clk_tck(void);
|
|
; #define CLOCKS_PER_SEC _clk_tck()
|
|
; clock_t clock(void);
|
|
;
|
|
; clk_tck()'s test-values are based on the numbers in "set_tv.s".
|
|
; If you change the numbers there, then change them here, too.
|
|
;
|
|
|
|
.export _clock, __clk_tck, clock_count
|
|
.interruptor update_clock, 2 ; (low priority)
|
|
.constructor init_clock
|
|
|
|
.import sreg: zp
|
|
.include "lynx.inc"
|
|
|
|
.macpack generic
|
|
|
|
|
|
.proc _clock
|
|
php
|
|
sei ; Disable interrupts
|
|
|
|
; Read the clock counter.
|
|
|
|
lda clock_count
|
|
ldx clock_count+1
|
|
ldy clock_count+2
|
|
|
|
plp ; Re-enable interrupts
|
|
sty sreg
|
|
stz sreg+1 ; Promote 24 bits up to 32 bits
|
|
rts
|
|
.endproc
|
|
|
|
;-----------------------------------------------------------------------------
|
|
; Return the number of clock ticks in one second.
|
|
;
|
|
__clk_tck:
|
|
ldx #$00 ; >50, >60, >75
|
|
ldy PBKUP
|
|
lda #<75
|
|
cpy #$20 + 1
|
|
blt @ok
|
|
lda #<60
|
|
cpy #$29 + 1
|
|
blt @ok
|
|
lda #<50
|
|
@ok: stz sreg ; return 32 bits
|
|
stz sreg+1
|
|
rts
|
|
|
|
;-----------------------------------------------------------------------------
|
|
; This interrupt handler increments a 24-bit counter at every video
|
|
; vertical-blanking time.
|
|
;
|
|
.segment "LOWCODE"
|
|
update_clock:
|
|
lda INTSET
|
|
and #%00000100
|
|
beq @NotVBlank ; Not vertical-blank interrupt
|
|
|
|
inc clock_count
|
|
bne @L1
|
|
inc clock_count+1
|
|
bne @L1
|
|
inc clock_count+2
|
|
@L1: ;clc ; General interrupt was not reset
|
|
@NotVBlank:
|
|
rts
|
|
|
|
;-----------------------------------------------------------------------------
|
|
; Enable the interrupt that update_clock needs.
|
|
;
|
|
.segment "ONCE"
|
|
init_clock:
|
|
lda #%10000000
|
|
tsb VTIMCTLA
|
|
rts
|
|
|
|
;-----------------------------------------------------------------------------
|
|
;
|
|
.bss
|
|
clock_count:
|
|
.res 3
|