yangsong8-a1 opened a new pull request, #21113:
URL: https://github.com/apache/nuttx/pull/21113
## Summary
This PR generalizes the bulk copy to the OPOST case. It replaces
uart_putxmitbuf
with uart_putxmitbuffer(), which copies a whole buffer into the TX ring in
bulk
with memcpy over the contiguous free region, preserving the existing
xmit.lock
and ring-buffer invariants. uart_putxmitchar() becomes a thin forwarder to
it.
uart_write()/uart_writev() and uart_irqwrite() are rewritten to use memchr()
to
locate the next character that needs output post-processing (CR under OCRNL,
NL
under ONLCR/ONLRET), bulk-copy the run of ordinary bytes before it, then
handle
that single character. When no output translation is enabled (raw mode) the
whole payload is copied in one bulk operation.
## Impact
- Feature: no new user-facing feature; this is a write()/console-output
throughput optimization for all UART-based serial ports.
- Users: large writes to serial devices (e.g. CDC/ACM block transfers, and
now also tty/console ports with OPOST/ONLCR enabled) are copied into the TX
ring in bulk instead of byte-by-byte.
## Testing
sim:nsh / qemu-armv7a:nsh
Ran uname -a, help, ls -lR /, free, cat /proc/version, uptime, poweroff.
Boots, all commands run, clean exit (no hang). Output intact, all lines
CRLF-terminated (ONLCR via the new memchr path correct).
sim:usbdev
nsh > conn 1 # bring up CDC/ACM
nsh > dd if=/dev/zero of=/dev/ttyACM0 bs=4095 count=256
host> sudo dd if=/dev/ttyACMx of=/dev/null bs=4095 count=256
iflag=fullblock
Integrity PASS
performance (real product HW, CDC/ACM):
dd if=/dev/zero of=/dev/ttyACM0 bs=4095 count=256
4266 KB/s -> 20334 KB/s. Also verified functionally correct on the product.
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