git.sur5r.net Git - cc65/blob - libsrc/c64/systime.s

   1 ;
   2 ; Stefan Haubenthal, 27.7.2009
   3 ;
   4 ; time_t _systime (void);
   5 ; /* Similar to time(), but:
   6 ;  *   - Is not ISO C
   7 ;  *   - Does not take the additional pointer
   8 ;  *   - Does not set errno when returning -1
   9 ;  */
  10 ;
  11
  12         .include        "time.inc"
  13         .include        "c64.inc"
  14
  15         .importzp               tmp1, tmp2
  16
  17 .code
  18
  19 ; Jan 1st 1970, CIA #1 TOD
  20 .proc   __systime
  21
  22         lda     #70
  23         sta     TM + tm::tm_year
  24         lda     #1
  25         sta     TM + tm::tm_mday
  26         lda     CIA1_TODHR
  27         bpl     AM
  28         and     #%01111111
  29         sed
  30         clc
  31         adc     #$12
  32         cld
  33 AM:     jsr     BCD2dec
  34         sta     TM + tm::tm_hour
  35         lda     CIA1_TODMIN
  36         jsr     BCD2dec
  37         sta     TM + tm::tm_min
  38         lda     CIA1_TODSEC
  39         jsr     BCD2dec
  40         sta     TM + tm::tm_sec
  41         lda     CIA1_TOD10              ; Dummy read to unfreeze
  42         lda     #<TM
  43         ldx     #>TM
  44         jmp     _mktime
  45
  46 ; dec = (((BCD>>4)*10) + (BCD&0xf))
  47 BCD2dec:tax
  48         and     #%00001111
  49         sta     tmp1
  50         txa
  51         and     #%11110000      ; *16
  52         lsr                     ; *8
  53         sta     tmp2
  54         lsr
  55         lsr                     ; *2
  56         adc     tmp2            ; = *10
  57         adc     tmp1
  58         rts
  59
  60 .endproc
  61
  62 .bss
  63
  64 TM:     .tag    tm