Simplify and comment the translation between registers and struct tm. Signed-off-by: Michael Davidsaver <mdavidsa...@gmail.com> --- hw/timer/ds1338.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/hw/timer/ds1338.c b/hw/timer/ds1338.c index b56db5852e..637a0f4246 100644 --- a/hw/timer/ds1338.c +++ b/hw/timer/ds1338.c @@ -89,9 +89,13 @@ static void capture_current_time(DS1338State *s) */ struct tm now; qemu_get_timedate(&now, s->offset); + s->nvram[R_SEC] = to_bcd(now.tm_sec); s->nvram[R_MIN] = to_bcd(now.tm_min); if (ARRAY_FIELD_EX32(s->nvram, HOUR, SET12)) { + /* 12 hour mode. + * map 0-23 to 1-12 am/pm + */ int tmp = now.tm_hour; if (tmp % 12 == 0) { tmp += 12; @@ -101,7 +105,9 @@ static void capture_current_time(DS1338State *s) } else { s->nvram[R_HOUR] = R_HOUR_SET12_MASK | R_HOUR_AMPM_MASK | to_bcd(tmp - 12); } + } else { + /* 24 hour mode. */ s->nvram[R_HOUR] = to_bcd(now.tm_hour); } s->nvram[R_WDAY] = (now.tm_wday + s->wday_offset) % 7 + 1; @@ -178,14 +184,13 @@ static int ds1338_send(I2CSlave *i2c, uint8_t data) break; case R_HOUR: if (FIELD_EX32(data, HOUR, SET12)) { - int tmp = from_bcd(FIELD_EX32(data, HOUR, HOUR12)); + /* 12 hour (1-12) */ + /* read and wrap 1-12 -> 0-11 */ + now.tm_hour = from_bcd(FIELD_EX32(data, HOUR, HOUR12)) % 12u; if (FIELD_EX32(data, HOUR, AMPM)) { - tmp += 12; + now.tm_hour += 12; } - if (tmp % 12 == 0) { - tmp -= 12; - } - now.tm_hour = tmp; + } else { now.tm_hour = from_bcd(FIELD_EX32(data, HOUR, HOUR24)); } -- 2.11.0