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The following commit(s) were added to refs/heads/master by this push:
new c4da1b5b9 system/cu: Optimize I/O performance with batch read/write
c4da1b5b9 is described below
commit c4da1b5b9f3c6ab24014f919320bad8a5ee845d7
Author: fangpeina <[email protected]>
AuthorDate: Tue Jul 8 13:19:45 2025 +0800
system/cu: Optimize I/O performance with batch read/write
Due to DMA-based transfers, the rx buffer can receive a large amount
of data at once. The previous character-by-character processing approach
was inefficient.
Modify character-by-character read to block read of the entire buffer.
This improves throughput and reduces CPU overhead, especially for high-speed
serial communication or other DMA-based transfers.
Signed-off-by: fangpeina <[email protected]>
---
system/cu/cu_main.c | 84 +++++++++++++++++++++++++++++++++++------------------
1 file changed, 55 insertions(+), 29 deletions(-)
diff --git a/system/cu/cu_main.c b/system/cu/cu_main.c
index 20cd101b5..8d25038ed 100644
--- a/system/cu/cu_main.c
+++ b/system/cu/cu_main.c
@@ -103,16 +103,16 @@ static FAR void *cu_listener(FAR void *parameter)
for (; ; )
{
+ char buf[CONFIG_LINE_MAX];
int rc;
- char ch;
- rc = read(cu->devfd, &ch, 1);
+ rc = read(cu->devfd, buf, sizeof(buf));
if (rc <= 0)
{
break;
}
- rc = write(STDOUT_FILENO, &ch, 1);
+ rc = write(STDOUT_FILENO, buf, rc);
if (rc <= 0)
{
break;
@@ -289,6 +289,7 @@ int main(int argc, FAR char *argv[])
int start_of_line = 1;
int exitval = EXIT_FAILURE;
bool badarg = false;
+ bool escaping = false;
/* Initialize global data */
@@ -436,55 +437,80 @@ int main(int argc, FAR char *argv[])
while (!cu->force_exit)
{
- char ch;
+ char buf[CONFIG_LINE_MAX];
+ ssize_t nwrite = 0;
+ ssize_t nread;
+ ssize_t i;
- if (read(STDIN_FILENO, &ch, 1) <= 0)
+ /* Read multiple characters at once (blocking) */
+
+ nread = read(STDIN_FILENO, buf, sizeof(buf));
+ if (nread <= 0)
{
continue;
}
- if (start_of_line == 1 && ch == cu->escape)
+ /* Process each character */
+
+ for (i = 0; i < nread; i++)
{
- /* We've seen and escape (~) character, echo it to local
- * terminal and read the next char from serial
- */
+ char ch = buf[i];
- write(STDOUT_FILENO, &ch, 1);
+ /* Check if we're waiting for an escape command character */
- if (read(STDIN_FILENO, &ch, 1) <= 0)
+ if (escaping)
{
- continue;
+ /* We got the escape character in previous read,
+ * now process the command character
+ */
+
+ escaping = false;
+ if (cu_cmd(cu, ch) == 1)
+ {
+ cu->force_exit = true;
+ nread = i;
+ break;
+ }
}
- if (ch == cu->escape)
+ if (start_of_line == 1 && ch == cu->escape)
{
- /* Escaping a tilde: handle like normal char */
+ /* Normal character */
+
+ if (i > nwrite)
+ {
+ write(cu->devfd, &buf[nwrite], i - nwrite);
+ }
+
+ nwrite = i + 1;
+
+ /* We've seen and escape (~) character, echo it to local
+ * terminal and read the next char from serial
+ */
- write(cu->devfd, &ch, 1);
+ write(STDOUT_FILENO, &ch, 1);
+ start_of_line = 0;
+ escaping = true;
continue;
}
+
+ /* Determine if we are now at the start of a new line or not */
+
+ if (ch == '\n' || ch == '\r')
+ {
+ start_of_line = 1;
+ }
else
{
- if (cu_cmd(cu, ch) == 1)
- {
- break;
- }
+ start_of_line = 0;
}
}
/* Normal character */
- write(cu->devfd, &ch, 1);
-
- /* Determine if we are now at the start of a new line or not */
-
- if (ch == '\n' || ch == '\r')
- {
- start_of_line = 1;
- }
- else
+ if (nread > nwrite)
{
- start_of_line = 0;
+ write(cu->devfd, &buf[nwrite], nread - nwrite);
}
}
