diff --git a/Documentation/NuttxPortingGuide.html b/Documentation/NuttxPortingGuide.html
index 44059c231d..c164f5a54b 100644
--- a/Documentation/NuttxPortingGuide.html
+++ b/Documentation/NuttxPortingGuide.html
@@ -16,7 +16,7 @@
by
Gregory Nutt
- Last Update: March 15, 2008
+ Last Update: July 21, 2008
Table of Contents
@@ -1509,6 +1509,10 @@ The system can be re-made subsequently by just typing make.
structures. The system manages a pool of preallocated
watchdog structures to minimize dynamic allocations
+
+ CONFIG_DEV_FIFO_SIZE: Size, in bytes, of the buffer to allocated
+ for FIFO support (default is 1024).
+
Network Support
diff --git a/configs/README.txt b/configs/README.txt
index ba746ce687..1de7e8def8 100644
--- a/configs/README.txt
+++ b/configs/README.txt
@@ -239,6 +239,8 @@ defconfig -- This is a configuration file similar to the Linux
CONFIG_PREALLOC_WDOGS - The number of pre-allocated watchdog
structures. The system manages a pool of preallocated
watchdog structures to minimize dynamic allocations
+ CONFIG_DEV_FIFO_SIZE - Size, in bytes, of the buffer to allocated
+ for FIFO support
TCP/IP and UDP support via uIP
CONFIG_NET - Enable or disable all network features
diff --git a/drivers/fifo.c b/drivers/fifo.c
index 0fefc80c89..44a2dd69be 100644
--- a/drivers/fifo.c
+++ b/drivers/fifo.c
@@ -53,13 +53,14 @@
#include
#include
-/****************************************************************************
- * Definitions
- ****************************************************************************/
-
#ifndef CONFIG_DEV_FIFO_SIZE
# define CONFIG_DEV_FIFO_SIZE 1024
#endif
+#if CONFIG_DEV_FIFO_SIZE > 0
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
/* Maximum number of open's supported on FIFO */
@@ -269,12 +270,11 @@ static ssize_t fifo_read(FAR struct file *filep, FAR char *buffer, size_t len)
struct inode *inode = filep->f_inode;
struct fifo_dev_s *dev = inode->i_private;
ssize_t nread = 0;
- ssize_t nrqstd = len;
- int ret;
+ fifo_ndx_t ret;
/* Some sanity checking */
#if CONFIG_DEBUG
- if (dev)
+ if (!dev)
{
return -ENODEV;
}
@@ -287,115 +287,45 @@ static ssize_t fifo_read(FAR struct file *filep, FAR char *buffer, size_t len)
return ERROR;
}
- /* Loop until all of the bytes have been read */
+ /* If the fifo is empty, then wait for something to be written to it */
- for (;;)
+ while (dev->d_wrndx == dev->d_rdndx)
{
- ssize_t nbytes;
-
- /* Is there data available at the end of the buffer? When the write
- * index is smaller than the read index, then all of the data from the
- * read index to the end of the buffer is available for reading.
- */
-
- if (dev->d_rdndx > dev->d_wrndx)
+#warning "Support for O_NONBLOCK needed"
+ dev->d_nreaders++;
+ sched_lock();
+ sem_post(&dev->d_bfsem);
+ ret = sem_wait(&dev->d_rdsem);
+ sched_unlock();
+ if (ret < 0 || sem_wait(&dev->d_bfsem) < 0)
{
- /* Yes.. How many bytes are available at the end of the circular buffer */
-
- nbytes = CONFIG_DEV_FIFO_SIZE - dev->d_rdndx;
- if (nbytes > 0)
- {
- /* Read bytes from the end of the buffer. Are there more than we
- * need?
- */
-
- if (nbytes > nrqstd)
- {
- nbytes = nrqstd;
- }
-
- /* Copy the correct number of bytes */
-
- memcpy(&buffer[nread], &dev->d_buffer[dev->d_rdndx], nbytes);
-
- /* Then update all indices and counts */
-
- nread += nbytes;
- nrqstd -= nbytes;
- dev->d_rdndx += nbytes;
- if (dev->d_rdndx >= CONFIG_DEV_FIFO_SIZE)
- {
- dev->d_rdndx = 0;
- }
- }
- }
-
- /* We have read some or all of the data at the end of the buffer. Do we still need more? */
-
- if (nrqstd > 0)
- {
- /* Yes... then we now that we have consumed all of the bytes at the end of the
- * buffer. How many bytes are available at the end of the circular buffer>
- */
-
- nbytes = dev->d_wrndx - dev->d_rdndx;
- if (nbytes > 0)
- {
- /* Read bytes from the beginning of the buffer. Are there more than we
- * need?
- */
-
- if (nbytes > nrqstd)
- {
- nbytes = nrqstd;
- }
-
- /* Copy the correct number of bytes */
-
- memcpy(&buffer[nread], &dev->d_buffer[dev->d_rdndx], nbytes);
-
- /* Then update all indices and counts */
-
- nread += nbytes;
- nrqstd -= nbytes;
- dev->d_rdndx += nbytes;
- }
- }
-
- /* Was anything read? */
-
- if (nread > 0)
- {
- /* Yes.. Notify the waiting writers that space is again available */
-
- if (dev->d_nwriters > 0)
- {
- sem_post(&dev->d_wrsem);
- }
-
- /* Return the number of bytes read */
-
- sem_post(&dev->d_bfsem);
- return nread;
- }
- else
- {
- /* No.. wait for data to be added to the FIFO */
-
- dev->d_nreaders++;
- sched_lock();
- sem_post(&dev->d_bfsem);
- ret = sem_wait(&dev->d_rdsem);
- sched_unlock();
- fifo_semtake(&dev->d_bfsem);
- dev->d_nreaders--;
-
- if (ret != 0)
- {
- return ERROR;
- }
+ return ERROR;
}
}
+
+ /* Then return whatever is available in the FIFO (which is at least one byte) */
+
+ nread = 0;
+ while (nread < len && dev->d_wrndx != dev->d_rdndx)
+ {
+ *buffer++ = dev->d_buffer[dev->d_rdndx];
+ if (++dev->d_rdndx >= CONFIG_DEV_FIFO_SIZE)
+ {
+ dev->d_rdndx = 0;
+ }
+ nread++;
+ }
+
+ /* Notify any waiting writers that bytes have been removed from the buffer */
+
+ if (dev->d_nwriters > 0)
+ {
+ dev->d_nwriters--;
+ sem_post(&dev->d_wrsem);
+ }
+
+ sem_post(&dev->d_bfsem);
+ return nread;
}
/****************************************************************************
@@ -405,13 +335,13 @@ static ssize_t fifo_write(FAR struct file *filep, FAR const char *buffer, size_t
{
struct inode *inode = filep->f_inode;
struct fifo_dev_s *dev = inode->i_private;
- const char *src;
ssize_t nwritten = 0;
- ssize_t ntowrite = len;
-
+ ssize_t last;
+ int nxtwrndx;
+
/* Some sanity checking */
#if CONFIG_DEBUG
- if (dev)
+ if (!dev)
{
return -ENODEV;
}
@@ -426,112 +356,70 @@ static ssize_t fifo_write(FAR struct file *filep, FAR const char *buffer, size_t
/* Loop until all of the bytes have been written */
- src = buffer;
+ last = 0;
for (;;)
{
- ssize_t nbytes;
+ /* Calculate the write index AFTER the next byte is written */
- /* Is there space available at the end of the buffer? When the write
- * index is greater than the read index, then all of the data from the
- * write index to the end of the buffer is available for writing.
- */
-
- if (dev->d_wrndx >= dev->d_rdndx)
+ nxtwrndx = dev->d_wrndx + 1;
+ if (nxtwrndx >= CONFIG_DEV_FIFO_SIZE)
{
- /* How many bytes are available at the end of the circular buffer */
-
- nbytes = CONFIG_DEV_FIFO_SIZE - dev->d_wrndx;
- if (nbytes > 0)
- {
- /* Write bytes to the end of the buffer. Is there more space than we
- * need?
- */
-
- if (nbytes > ntowrite)
- {
- nbytes = ntowrite;
- }
-
- /* Copy the correct number of bytes */
-
- memcpy(&dev->d_buffer[dev->d_wrndx], &src[nwritten], nbytes);
-
- /* Then update all indices and counts */
-
- nwritten += nbytes;
- ntowrite -= nbytes;
- dev->d_wrndx += nbytes;
- if (dev->d_wrndx >= CONFIG_DEV_FIFO_SIZE)
- {
- dev->d_wrndx = 0;
- }
- }
- }
-
- /* Do we still need to write more data? */
-
- if (ntowrite > 0)
- {
- /* Yes... How many bytes are available at the end of the circular buffer */
-
- nbytes = dev->d_rdndx - dev->d_wrndx - 1;
- if (nbytes > 0)
- {
- /* Write bytes to the beginning of the buffer. Is there more space than we
- * need?
- */
-
- if (nbytes > ntowrite)
- {
- nbytes = ntowrite;
- }
-
- /* Copy the correct number of bytes */
-
- memcpy(&dev->d_buffer[dev->d_wrndx], &src[nwritten], nbytes);
-
- /* Then update all indices and counts */
-
- nwritten += nbytes;
- ntowrite -= nbytes;
- dev->d_wrndx += nbytes;
- }
+ nxtwrndx = 0;
}
- /* Was anything written? */
+ /* Would the next write overflow the circular buffer? */
- if (nwritten > 0)
- {
- /* Yes.. Notify the waiting reades that more data is available */
+ if (nxtwrndx != dev->d_rdndx)
+ {
+ /* No... copy the byte */
- if (dev->d_nreaders > 0)
- {
- sem_post(&dev->d_rdsem);
- }
- }
+ dev->d_buffer[dev->d_wrndx] = *buffer++;
+ dev->d_wrndx = nxtwrndx;
- /* Was everything written? */
+ /* Is the write complete? */
- if (ntowrite <= 0 )
- {
- /* Return the number of bytes written */
+ if (++nwritten >= len)
+ {
+ /* Yes.. Notify the waiting readers that more data is available */
- sem_post(&dev->d_bfsem);
- return len;
- }
+ if (dev->d_nreaders > 0)
+ {
+ dev->d_nreaders--;
+ sem_post(&dev->d_rdsem);
+ }
- /* There is more to be writtend.. wait for data to be removed from the FIFO */
+ /* Return the number of bytes written */
- dev->d_nwriters++;
- sched_lock();
- sem_post(&dev->d_bfsem);
- fifo_semtake(&dev->d_wrsem);
- sched_unlock();
- fifo_semtake(&dev->d_bfsem);
- dev->d_nwriters--;
+ sem_post(&dev->d_bfsem);
+ return len;
+ }
+ }
+ else
+ {
+ /* There is not enough room for the next byte. Was anything written in this pass? */
- src = &src[nwritten];
- nwritten = 0;
+ if (last < nwritten)
+ {
+ /* Yes.. Notify the waiting readers that more data is available */
+
+ if (dev->d_nreaders > 0)
+ {
+ dev->d_nreaders--;
+ sem_post(&dev->d_rdsem);
+ }
+ }
+
+ /* There is more to be written.. wait for data to be removed from the FIFO */
+
+#warning "Support for O_NONBLOCK needed"
+ dev->d_nwriters++;
+ sched_lock();
+ sem_post(&dev->d_bfsem);
+ fifo_semtake(&dev->d_wrsem);
+ sched_unlock();
+ fifo_semtake(&dev->d_bfsem);
+ last = nwritten;
+ }
}
}
@@ -551,8 +439,6 @@ static ssize_t fifo_write(FAR struct file *filep, FAR const char *buffer, size_t
* reading or writing, in the same way as an ordinary file. NuttX FIFOs need
* not be open at both ends before input or output operations on it.
*
- * In NuttX pipes are built on top of FIFOs
- *
* Inputs:
* pathname - The full path to the FIFO instance to attach to or to create
* (if not already created).
@@ -567,3 +453,4 @@ int mkfifo(FAR const char *pathname, mode_t mode)
{
return register_driver(pathname, &fifo_fops, mode, NULL);
}
+#endif
diff --git a/include/unistd.h b/include/unistd.h
index 8351b8c45f..4cce106e86 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -143,6 +143,7 @@ EXTERN int rmdir(FAR const char *pathname);
/* Other */
EXTERN int getopt(int argc, FAR char *const argv[], FAR const char *optstring);
+EXTERN int pipe(int filedes[2]);
#undef EXTERN
#if defined(__cplusplus)