[Xenomai-git] Alexis Berlemont : analogy: make __pre_abs_get more robust at ends of acquisitions
Module: xenomai-2.5
Branch: master
Commit: fe740c3a21a886e58b52f51c9874a1b1a445aa99
URL:
http://git.xenomai.org/?p=xenomai-2.5.git;a=commit;h=fe740c3a21a886e58b52f51c9874a1b1a445aa99
Author: Alexis Berlemont alexis.berlem...@gmail.com
Date: Mon Mar 1 01:09:44 2010 +0100
analogy: make __pre_abs_get more robust at ends of acquisitions
---
include/analogy/buffer.h | 28 ++--
1 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/include/analogy/buffer.h b/include/analogy/buffer.h
index 7b210b8..0e8f279 100644
--- a/include/analogy/buffer.h
+++ b/include/analogy/buffer.h
@@ -201,12 +201,36 @@ static inline int __pre_put(a4l_buf_t * buf, unsigned
long count)
static inline int __pre_abs_get(a4l_buf_t * buf, unsigned long count)
{
- if (!(buf-tmp_count == 0 buf-cns_count == 0)
- (long)(count - buf-tmp_count) 0) {
+
+ /* The first time, we expect the buffer to be properly filled
+ before the trigger occurence; by the way, we need tmp_count to
+ have been initialized and tmp_count is updated right here */
+ if (buf-tmp_count == 0 || buf-cns_count == 0)
+ goto out;
+
+ /* At the end of the acquisition, the user application has
+ written the defined amount of data into the buffer; so the
+ last time, the DMA channel can easily overtake the tmp
+ frontier because no more data were sent from user space;
+ therefore no useless alarm should be sent */
+ if ((long)(count - buf-end_count) 0)
+ goto out;
+
+ /* Once the exception are passed, we check that the DMA
+ transfer has not overtaken the last record of the production
+ count (tmp_count was updated with prd_count the last time
+ __pre_abs_get was called). We must understand that we cannot
+ compare the current DMA count with the current production
+ count because even if, right now, the production count is
+ higher than the DMA count, it does not mean that the DMA count
+ was not greater a few cycles before; in such case, the DMA
+ channel would have retrieved the wrong data */
+ if ((long)(count - buf-tmp_count) 0) {
set_bit(A4L_BUF_ERROR_NR, buf-evt_flags);
return -EPIPE;
}
+out:
buf-tmp_count = buf-prd_count;
return 0;
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[Xenomai-git] Alexis Berlemont : analogy: make __pre_abs_get more robust at ends of acquisitions
Module: xenomai-abe
Branch: analogy
Commit: fe740c3a21a886e58b52f51c9874a1b1a445aa99
URL:
http://git.xenomai.org/?p=xenomai-abe.git;a=commit;h=fe740c3a21a886e58b52f51c9874a1b1a445aa99
Author: Alexis Berlemont alexis.berlem...@gmail.com
Date: Mon Mar 1 01:09:44 2010 +0100
analogy: make __pre_abs_get more robust at ends of acquisitions
---
include/analogy/buffer.h | 28 ++--
1 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/include/analogy/buffer.h b/include/analogy/buffer.h
index 7b210b8..0e8f279 100644
--- a/include/analogy/buffer.h
+++ b/include/analogy/buffer.h
@@ -201,12 +201,36 @@ static inline int __pre_put(a4l_buf_t * buf, unsigned
long count)
static inline int __pre_abs_get(a4l_buf_t * buf, unsigned long count)
{
- if (!(buf-tmp_count == 0 buf-cns_count == 0)
- (long)(count - buf-tmp_count) 0) {
+
+ /* The first time, we expect the buffer to be properly filled
+ before the trigger occurence; by the way, we need tmp_count to
+ have been initialized and tmp_count is updated right here */
+ if (buf-tmp_count == 0 || buf-cns_count == 0)
+ goto out;
+
+ /* At the end of the acquisition, the user application has
+ written the defined amount of data into the buffer; so the
+ last time, the DMA channel can easily overtake the tmp
+ frontier because no more data were sent from user space;
+ therefore no useless alarm should be sent */
+ if ((long)(count - buf-end_count) 0)
+ goto out;
+
+ /* Once the exception are passed, we check that the DMA
+ transfer has not overtaken the last record of the production
+ count (tmp_count was updated with prd_count the last time
+ __pre_abs_get was called). We must understand that we cannot
+ compare the current DMA count with the current production
+ count because even if, right now, the production count is
+ higher than the DMA count, it does not mean that the DMA count
+ was not greater a few cycles before; in such case, the DMA
+ channel would have retrieved the wrong data */
+ if ((long)(count - buf-tmp_count) 0) {
set_bit(A4L_BUF_ERROR_NR, buf-evt_flags);
return -EPIPE;
}
+out:
buf-tmp_count = buf-prd_count;
return 0;
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[Xenomai-git] Alexis Berlemont : analogy: make __pre_abs_get more robust at ends of acquisitions
Module: xenomai-abe
Branch: analogy
Commit: 32a3e77984c7b00548a70ba7a236a815d3497511
URL:
http://git.xenomai.org/?p=xenomai-abe.git;a=commit;h=32a3e77984c7b00548a70ba7a236a815d3497511
Author: Alexis Berlemont alexis.berlem...@gmail.com
Date: Mon Mar 1 01:09:44 2010 +0100
analogy: make __pre_abs_get more robust at ends of acquisitions
---
include/analogy/buffer.h | 28 ++--
1 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/include/analogy/buffer.h b/include/analogy/buffer.h
index 7b210b8..0e8f279 100644
--- a/include/analogy/buffer.h
+++ b/include/analogy/buffer.h
@@ -201,12 +201,36 @@ static inline int __pre_put(a4l_buf_t * buf, unsigned
long count)
static inline int __pre_abs_get(a4l_buf_t * buf, unsigned long count)
{
- if (!(buf-tmp_count == 0 buf-cns_count == 0)
- (long)(count - buf-tmp_count) 0) {
+
+ /* The first time, we expect the buffer to be properly filled
+ before the trigger occurence; by the way, we need tmp_count to
+ have been initialized and tmp_count is updated right here */
+ if (buf-tmp_count == 0 || buf-cns_count == 0)
+ goto out;
+
+ /* At the end of the acquisition, the user application has
+ written the defined amount of data into the buffer; so the
+ last time, the DMA channel can easily overtake the tmp
+ frontier because no more data were sent from user space;
+ therefore no useless alarm should be sent */
+ if ((long)(count - buf-end_count) 0)
+ goto out;
+
+ /* Once the exception are passed, we check that the DMA
+ transfer has not overtaken the last record of the production
+ count (tmp_count was updated with prd_count the last time
+ __pre_abs_get was called). We must understand that we cannot
+ compare the current DMA count with the current production
+ count because even if, right now, the production count is
+ higher than the DMA count, it does not mean that the DMA count
+ was not greater a few cycles before; in such case, the DMA
+ channel would have retrieved the wrong data */
+ if ((long)(count - buf-tmp_count) 0) {
set_bit(A4L_BUF_ERROR_NR, buf-evt_flags);
return -EPIPE;
}
+out:
buf-tmp_count = buf-prd_count;
return 0;
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