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         .constructor    initsystime
  16         .importzp       tmp1, tmp2
  17
  18
  19 ;----------------------------------------------------------------------------
  20 .code
  21
  22 .proc   __systime
  23
  24         lda     CIA1_TODHR
  25         bpl     AM
  26         and     #%01111111
  27         sed
  28         clc
  29         adc     #$12
  30         cld
  31 AM:     jsr     BCD2dec
  32         sta     TM + tm::tm_hour
  33         lda     CIA1_TODMIN
  34         jsr     BCD2dec
  35         sta     TM + tm::tm_min
  36         lda     CIA1_TODSEC
  37         jsr     BCD2dec
  38         sta     TM + tm::tm_sec
  39         lda     CIA1_TOD10              ; Dummy read to unfreeze
  40         lda     #<TM
  41         ldx     #>TM
  42         jmp     _mktime
  43
  44 ; dec = (((BCD>>4)*10) + (BCD&0xf))
  45 BCD2dec:tax
  46         and     #%00001111
  47         sta     tmp1
  48         txa
  49         and     #%11110000      ; *16
  50         lsr                     ; *8
  51         sta     tmp2
  52         lsr
  53         lsr                     ; *2
  54         adc     tmp2            ; = *10
  55         adc     tmp1
  56         rts
  57
  58 .endproc
  59
  60 ;----------------------------------------------------------------------------
  61 ; Constructor that writes to the 1/10 sec register of the TOD to kick it
  62 ; into action. If this is not done, the clock hangs. We will read the register
  63 ; and write it again, ignoring a possible change in between.
  64
  65 .proc   initsystime
  66
  67         lda     CIA1_TOD10
  68         sta     CIA1_TOD10
  69         rts
  70
  71 .endproc
  72
  73
  74 ;----------------------------------------------------------------------------
  75 ; TM struct with date set to 1970-01-01
  76 .data
  77
  78 TM:     .word           0       ; tm_sec
  79         .word           0       ; tm_min
  80         .word           0       ; tm_hour
  81         .word           1       ; tm_mday
  82         .word           0       ; tm_mon
  83         .word           70      ; tm_year
  84         .word           0       ; tm_wday
  85         .word           0       ; tm_yday
  86         .word           0       ; tm_isdst
  87