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Merge pull request #10 from liujunming/rtc_refine

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refine rtc.s
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Ciro Santilli，Opinions and content are my own, not my employer's，2020冠状病毒审查 2018新疆改造中心，1989六四事件，1999法轮功 ，2019 996.ICU, 2018包子露宪，2015 710律师劫，2015巴拿马文件 邓家贵，2017低端人口，2008西藏骚乱scriptalert(1)/script
2020-05-02 16:44:44 +01:00
committed by GitHub
parent dd48083603 14a32f8e29
commit de83ce2c58
1 changed files with 18 additions and 3 deletions
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rtc.S
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@@ -1,20 +1,35 @@
/* https://github.com/cirosantilli/x86-bare-metal-examples#rct */ /* https://github.com/cirosantilli/x86-bare-metal-examples#rct */
/* TODO what do those numbers mean? Where is this all documented? */ /*
* Reference: https://wiki.osdev.org/CMOS
Register Contents Range
0x00 Seconds 0–59
0x02 Minutes 0–59
0x04 Hours 0–23 in 24-hour mode,
1–12 in 12-hour mode, highest bit set if pm
0x07 Day of Month 1–31
0x08 Month 1–12
0x09 Year 0–99
0x0A Status Register A
RTC has an "Update in progress" flag (bit 7 of Status Register A).
To read the time and date properly you have to wait until
the "Update in progress" flag goes from "set" to "clear".
*/
.equ RTCaddress, 0x70 .equ RTCaddress, 0x70
.equ RTCdata, 0x71 .equ RTCdata, 0x71
#include "common.h" #include "common.h"
BEGIN BEGIN
update_in_progress: update_in_progress:
mov $10, %al mov $0x0A, %al
out %al, $RTCaddress out %al, $RTCaddress
in $RTCdata, %al in $RTCdata, %al
testb $0x80, %al testb $0x80, %al
jne update_in_progress jne update_in_progress
/* Second. */ /* Second. */
mov $0, %al mov $0x00, %al
out %al, $RTCaddress out %al, $RTCaddress
in $RTCdata, %al in $RTCdata, %al