eb9872c684
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!
83 lines
1.7 KiB
ArmAsm
83 lines
1.7 KiB
ArmAsm
;
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; Oliver Schmidt, 16.8.2018
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;
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; int clock_settime (clockid_t clk_id, const struct timespec *tp);
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;
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.include "time.inc"
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.include "c64.inc"
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.importzp sreg, ptr1
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.import pushax, pusheax, ldax0sp, ldeaxidx
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.import tosdiveax, incsp3, return0
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.import TM, load_tenth
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;----------------------------------------------------------------------------
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.code
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.proc _clock_settime
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jsr pushax
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jsr _localtime
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sta ptr1
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stx ptr1+1
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ldy #.sizeof(tm)-1
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@L1: lda (ptr1),y
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sta TM,y
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dey
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bpl @L1
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lda TM + tm::tm_hour
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jsr dec2BCD
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tax ; Force flags
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bne @L2
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lda #$92 ; 12 AM
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bne @L3
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@L2: cmp #$13 ; 1 PM
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bcc @L3
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sed
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sbc #$12
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cld
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ora #%10000000
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@L3: sta CIA1_TODHR
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lda TM + tm::tm_min
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jsr dec2BCD
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sta CIA1_TODMIN
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lda TM + tm::tm_sec
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jsr dec2BCD
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sta CIA1_TODSEC
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jsr ldax0sp
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ldy #3+timespec::tv_nsec
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jsr ldeaxidx
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jsr pusheax
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jsr load_tenth
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jsr tosdiveax
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sta CIA1_TOD10
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jsr incsp3
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jmp return0
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.endproc
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;----------------------------------------------------------------------------
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; Just sum up the value in BCD mode.
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; http://forum.6502.org/viewtopic.php?p=7629#p7629
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.proc dec2BCD
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tax
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dex
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bmi @L9
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lda #0
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clc
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sed
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@L1: adc #1
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dex
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bpl @L1
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cld
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@L9: rts
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.endproc
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