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cc65/libsrc/cbm510/gettime.s
Oliver Schmidt eb9872c684 Added clock_settime() for some CBMs.
The CIA TOD only stores the time but not the date. Therefore the date set by clock_settime() ist just stored inside the C library for retrieval via clock_gettime().

The "very special" handling of 12AM/PM is based on https://groups.google.com/d/msg/comp.sys.cbm/ysVYSX4AMbc/vHrXCWEhCOUJ saying:

==========

24hr: Wr => Rd => Nx
--------------------
  0 : 92 => 12 => 01   <= Switch from 00 to 01 (24-hour notation)
  1 : 01 => 01 => 02
  2 : 02 => 02 => 03
 11 : 11 => 11 => 92
 12 : 12 => 92 => 81   <= Switch from 12 to 13 (24-hour notation)
 13 : 81 => 81 => 82
 14 : 82 => 82 => 83
 23 : 91 => 91 => 12

1. column ("24hr"): hour to be tested (decimal)
2. column ("Wr"):   hour written to TOD register (BCD)
3. column ("Rd"):   hour read from TOD register (BCD) immediately after writing the value in column 2 to see the conversion between AM/PM, if any
4. column ("Nx"):   next hour (BCD) after the hour switch

==========

Thanks Paul!
2018-08-18 01:29:40 +02:00

95 lines
2.2 KiB
ArmAsm

;
; Stefan Haubenthal, 2009-07-27
; Ullrich von Bassewitz, 2009-09-24
; Oliver Schmidt, 2018-08-14
;
; int clock_gettime (clockid_t clk_id, struct timespec *tp);
;
.include "time.inc"
.include "cbm510.inc"
.include "extzp.inc"
.import pushax, pusheax, tosmul0ax, steaxspidx, incsp1
.import sys_bank, restore_bank
.import TM, load_tenth
.importzp sreg, tmp1, tmp2
;----------------------------------------------------------------------------
.code
.proc _clock_gettime
jsr sys_bank
jsr pushax
jsr pushax
ldy #CIA::TODHR
lda (cia2),y
sed
tax ; Save PM flag
and #%01111111
cmp #$12 ; 12 AM/PM
bcc @L1
sbc #$12
@L1: inx ; Get PM flag
bpl @L2
clc
adc #$12
@L2: cld
jsr BCD2dec
sta TM + tm::tm_hour
ldy #CIA::TODMIN
lda (cia2),y
jsr BCD2dec
sta TM + tm::tm_min
ldy #CIA::TODSEC
lda (cia2),y
jsr BCD2dec
sta TM + tm::tm_sec
lda #<TM
ldx #>TM
jsr _mktime
ldy #timespec::tv_sec
jsr steaxspidx ; Pops address pushed by 2. pushax
jsr load_tenth
jsr pusheax
ldy #CIA::TOD10
lda (cia2),y
ldx #>$0000
jsr tosmul0ax
ldy #timespec::tv_nsec
jsr steaxspidx ; Pops address pushed by 1. pushax
jsr incsp1
lda #0
tax
jmp restore_bank
.endproc
;----------------------------------------------------------------------------
; dec = (((BCD>>4)*10) + (BCD&0xf))
.proc BCD2dec
tax
and #%00001111
sta tmp1
txa
and #%11110000 ; *16
lsr ; *8
sta tmp2
lsr
lsr ; *2
adc tmp2 ; = *10
adc tmp1
rts
.endproc