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esp32/usb: Improve speed of USB CDC output. 

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George 2021-09-24 14:11:44 +10:00
parent 549448e8bb
commit ba940250a5
1 changed files with 18 additions and 5 deletions
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23
ports/esp32/usb.c
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@ -93,15 +93,28 @@ void usb_tx_strn(const char *str, size_t len) {
}
while (len) {
size_t l = len;
if (l > CONFIG_USB_CDC_TX_BUFSIZE) {
l = CONFIG_USB_CDC_TX_BUFSIZE;
// Get amount of CDC output buffer space available, making sure
// there is at least one byte available.
size_t avail = tud_cdc_n_write_available(CDC_ITF);
if (avail == 0) {
if (tinyusb_cdcacm_write_flush(CDC_ITF, pdMS_TO_TICKS(1000)) != ESP_OK) {
return;
}
tinyusb_cdcacm_write_queue(CDC_ITF, (uint8_t *)str, l);
tinyusb_cdcacm_write_flush(CDC_ITF, pdMS_TO_TICKS(1000));
avail = tud_cdc_n_write_available(CDC_ITF);
}
// Write as much data as possible.
size_t l = len;
if (l > avail) {
l = avail;
}
tud_cdc_n_write(CDC_ITF, (uint8_t *)str, l);
str += l;
len -= l;
}
// Queue a flush to write out the data in the CDC buffer (if any).
tud_cdc_n_write_flush(CDC_ITF);
}
#endif // CONFIG_USB_ENABLED