Hi,
From: zeroway <linw...@ruijie.com.cn>
when the duration now - buft_start reach to some kind of value,
which will get the multiply hda_bytes_per_second(st) * (now - buft_start)
overflow,
instead of calculate the wanted_r/wpos from start time to current time,
here calculate the each timer tick delta data first in wanted_r/wpos_delta,
and sum it all to wanted_r/wpos to avoid the overflow
you could avoid the multiplication overflow with the following code
#include "qemu/host-utils.h"
int64_t wanted_rpos = muldiv64(now - buft_start,
hda_bytes_per_second(st),
NANOSECONDS_PER_SECOND);
and
int64_t wanted_wpos = muldiv64(now - buft_start,
hda_bytes_per_second(st),
NANOSECONDS_PER_SECOND);
This would be a less intrusive change. The wanted_pos with your code
will grow slower than with the original code because you sum up
truncated results from the division by NANOSECONDS_PER_SECONDS rounded
down to next multiple of 4.
With best regards,
Volker
Signed-off-by: zeroway <linw...@ruijie.com.cn>
---
hw/audio/hda-codec.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/hw/audio/hda-codec.c b/hw/audio/hda-codec.c
index c51d8ba617..747188221a 100644
--- a/hw/audio/hda-codec.c
+++ b/hw/audio/hda-codec.c
@@ -169,6 +169,8 @@ struct HDAAudioStream {
uint8_t buf[8192]; /* size must be power of two */
int64_t rpos;
int64_t wpos;
+ int64_t wanted_rpos;
+ int64_t wanted_wpos;
QEMUTimer *buft;
int64_t buft_start;
};
@@ -226,16 +228,18 @@ static void hda_audio_input_timer(void *opaque)
int64_t wpos = st->wpos;
int64_t rpos = st->rpos;
- int64_t wanted_rpos = hda_bytes_per_second(st) * (now - buft_start)
+ int64_t wanted_rpos_delta = hda_bytes_per_second(st) * (now - buft_start)
/ NANOSECONDS_PER_SECOND;
- wanted_rpos &= -4; /* IMPORTANT! clip to frames */
+ st->wanted_rpos += wanted_rpos_delta;
+ st->wanted_rpos &= -4; /* IMPORTANT! clip to frames */
- if (wanted_rpos <= rpos) {
+ st->buft_start = now;
+ if (st->wanted_rpos <= rpos) {
/* we already transmitted the data */
goto out_timer;
}
- int64_t to_transfer = MIN(wpos - rpos, wanted_rpos - rpos);
+ int64_t to_transfer = MIN(wpos - rpos, st->wanted_rpos - rpos);
while (to_transfer) {
uint32_t start = (rpos & B_MASK);
uint32_t chunk = MIN(B_SIZE - start, to_transfer);
@@ -290,16 +294,18 @@ static void hda_audio_output_timer(void *opaque)
int64_t wpos = st->wpos;
int64_t rpos = st->rpos;
- int64_t wanted_wpos = hda_bytes_per_second(st) * (now - buft_start)
+ int64_t wanted_wpos_delta = hda_bytes_per_second(st) * (now - buft_start)
/ NANOSECONDS_PER_SECOND;
- wanted_wpos &= -4; /* IMPORTANT! clip to frames */
+ st->wanted_wpos += wanted_wpos_delta;
+ st->wanted_wpos &= -4; /* IMPORTANT! clip to frames */
- if (wanted_wpos <= wpos) {
+ st->buft_start = now;
+ if (st->wanted_wpos <= wpos) {
/* we already received the data */
goto out_timer;
}
- int64_t to_transfer = MIN(B_SIZE - (wpos - rpos), wanted_wpos - wpos);
+ int64_t to_transfer = MIN(B_SIZE - (wpos - rpos), st->wanted_wpos - wpos);
while (to_transfer) {
uint32_t start = (wpos & B_MASK);
uint32_t chunk = MIN(B_SIZE - start, to_transfer);
@@ -420,6 +426,8 @@ static void hda_audio_set_running(HDAAudioStream *st, bool
running)
int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
st->rpos = 0;
st->wpos = 0;
+ st->wanted_rpos = 0;
+ st->wanted_wpos = 0;
st->buft_start = now;
timer_mod_anticipate_ns(st->buft, now + HDA_TIMER_TICKS);
} else {
