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cc65/libsrc/apple2/gmtime_dt.s
2024-01-01 19:12:51 +01:00

74 lines
1.7 KiB
ArmAsm

;
; Oliver Schmidt, 14.08.2018
; Colin Leroy-Mira, 2023 <colin@colino.net>
;
; struct tm * __fastcall__ gmtime_dt(const struct datetime *dt)
;
.export _gmtime_dt, tm_buf
.include "time.inc"
.include "zeropage.inc"
.include "errno.inc"
.include "mli.inc"
; Convert ProDOS date/time to a struct tm
; source date address in AX
; on stack:
; destination struct
_gmtime_dt:
sta ptr1
stx ptr1+1
; Get time
ldy #$03
lda (ptr1),y
sta tm_buf + tm::tm_hour
dey
lda (ptr1),y
sta tm_buf + tm::tm_min
; Get date
dey
lda (ptr1),y
lsr
php ; Save month msb
cmp #70 ; Year < 70?
bcs :+ ; No, leave alone
adc #100 ; Move 19xx to 20xx
: sta tm_buf + tm::tm_year
dey
lda (ptr1),y
tax ; Save day
plp ; Restore month msb
ror
lsr
lsr
lsr
lsr
beq erange ; [1..12] allows for validity check
tay
dey ; Move [1..12] to [0..11]
sty tm_buf + tm::tm_mon
txa ; Restore day
and #%00011111
sta tm_buf + tm::tm_mday
lda #<tm_buf ; Return pointer to tm_buf
ldx #>tm_buf
rts
; Load errno code and return NULL
erange: lda #ERANGE
sta ___errno
lda #$00
tax
rts
.bss
tm_buf:
.tag tm