2010-09-17 07:52:30

by Santiago Carot

Subject: [PATCH] Change the for loop to read blutooth clock in MCAP CSP

This is only a cosmetic change. Using a do..while loop
we avoid direct manipulation of counter loop variable
when error happens reading the BT clock.
---
health/mcap_sync.c | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/health/mcap_sync.c b/health/mcap_sync.c
index bc1ffcd..78cb163 100644
--- a/health/mcap_sync.c
+++ b/health/mcap_sync.c
@@ -406,18 +406,18 @@ static void initialize_caps(struct mcap_mcl *mcl)

/* Do clock read a number of times and measure latency */
avg = 0;
- for (i = 0; i < 20; ++i) {
+ i = 0;
+ do {
clock_gettime(CLK, &t1);
- if (!read_btclock(mcl, &btclock, &btaccuracy)) {
- --i;
+ if (!read_btclock(mcl, &btclock, &btaccuracy))
continue;
- }
clock_gettime(CLK, &t2);

latency = time_us(&t2) - time_us(&t1);
latencies[i] = latency;
avg += latency;
- }
+ i++;
+ } while (i < 20);
avg /= 20;

/* Calculate deviation */
--
1.7.2.3

2010-09-17 12:37:53

by Santiago Carot-Nemesio

Subject: Re: [PATCH] Change the for loop to read blutooth clock in MCAP CSP

Hi Elvis,

On 09/17/10 13:56, Elvis Pf?tzenreuter wrote:
> On Sep 17, 2010, at 4:52 AM, Santiago Carot-Nemesio wrote:
>
>> This is only a cosmetic change. Using a do..while loop
>> we avoid direct manipulation of counter loop variable
>> when error happens reading the BT clock.
>> ---
>> health/mcap_sync.c | 10 +++++-----
>> 1 files changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/health/mcap_sync.c b/health/mcap_sync.c
>> index bc1ffcd..78cb163 100644
>> --- a/health/mcap_sync.c
>> +++ b/health/mcap_sync.c
>> @@ -406,18 +406,18 @@ static void initialize_caps(struct mcap_mcl *mcl)
>>
>> /* Do clock read a number of times and measure latency */
>> avg = 0;
>> - for (i = 0; i< 20; ++i) {
>> + i = 0;
>> + do {
>> clock_gettime(CLK,&t1);
>> - if (!read_btclock(mcl,&btclock,&btaccuracy)) {
>> - --i;
>> + if (!read_btclock(mcl,&btclock,&btaccuracy))
>> continue;
>> - }
>> clock_gettime(CLK,&t2);
>>
>> latency = time_us(&t2) - time_us(&t1);
>> latencies[i] = latency;
>> avg += latency;
>> - }
>> + i++;
>> + } while (i< 20);
>> avg /= 20;
>>
>> /* Calculate deviation */
>> --
>> 1.7.2.3
>
> Looking again now, this (the logic, not the patch) may lead to an infinite loop, if for some reason the clock simply can't be read. One more thing to be fixed.--

Yes, you are rigth, I saw it too but I was waiting to speak with you. It
may be better set a maximum number of attempts and return a CSP error
code if it is not possible synchronize with remote device.

For now I think that this patch looks better than use a for loop here :P

2010-09-17 11:56:50

by Elvis Pfutzenreuter

Subject: Re: [PATCH] Change the for loop to read blutooth clock in MCAP CSP

On Sep 17, 2010, at 4:52 AM, Santiago Carot-Nemesio wrote:

> This is only a cosmetic change. Using a do..while loop
> we avoid direct manipulation of counter loop variable
> when error happens reading the BT clock.
> ---
> health/mcap_sync.c | 10 +++++-----
> 1 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/health/mcap_sync.c b/health/mcap_sync.c
> index bc1ffcd..78cb163 100644
> --- a/health/mcap_sync.c
> +++ b/health/mcap_sync.c
> @@ -406,18 +406,18 @@ static void initialize_caps(struct mcap_mcl *mcl)
>
> /* Do clock read a number of times and measure latency */
> avg = 0;
> - for (i = 0; i < 20; ++i) {
> + i = 0;
> + do {
> clock_gettime(CLK, &t1);
> - if (!read_btclock(mcl, &btclock, &btaccuracy)) {
> - --i;
> + if (!read_btclock(mcl, &btclock, &btaccuracy))
> continue;
> - }
> clock_gettime(CLK, &t2);
>
> latency = time_us(&t2) - time_us(&t1);
> latencies[i] = latency;
> avg += latency;
> - }
> + i++;
> + } while (i < 20);
> avg /= 20;
>
> /* Calculate deviation */
> --
> 1.7.2.3

Looking again now, this (the logic, not the patch) may lead to an infinite loop, if for some reason the clock simply can't be read. One more thing to be fixed.