diff options
| author | Keith Packard <keithp@keithp.com> | 2009-10-10 13:39:01 -0700 |
|---|---|---|
| committer | Keith Packard <keithp@keithp.com> | 2009-10-10 13:39:01 -0700 |
| commit | b8fc3975bd92037a0cf53b0ff2b0e05ce0ba668f (patch) | |
| tree | b5070f15d123ecb8095b31b96ca46ea0a9cef667 /src | |
| parent | e29961fdb2a48874c895829880eadbf13e094c0c (diff) | |
Send 0-length IN packet to flush USB after full packet
USB bulk transfers are a sequence of maximum-sized packets followed by
a short packet, which signals the end of the transfer. When the last
packet of the transfer would be a full-sized packet, an additional
packet of zero length is sent to signal the transfer end.
Signed-off-by: Keith Packard <keithp@keithp.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/ao_usb.c | 53 |
1 files changed, 38 insertions, 15 deletions
diff --git a/src/ao_usb.c b/src/ao_usb.c index 99f0715b..22665725 100644 --- a/src/ao_usb.c +++ b/src/ao_usb.c @@ -21,6 +21,7 @@ struct ao_task __xdata ao_usb_task; static __xdata uint16_t ao_usb_in_bytes; +static __xdata uint16_t ao_usb_in_bytes_last; static __xdata uint16_t ao_usb_out_bytes; static __xdata uint8_t ao_usb_iif; static __xdata uint8_t ao_usb_running; @@ -321,13 +322,40 @@ ao_usb_ep0(void) } } +/* Wait for a free IN buffer */ +static void +ao_usb_in_wait(void) +{ + for (;;) { + USBINDEX = AO_USB_IN_EP; + if ((USBCSIL & USBCSIL_INPKT_RDY) == 0) + break; + ao_sleep(&ao_usb_in_bytes); + } +} + +/* Send the current IN packet */ +static void +ao_usb_in_send(void) +{ + USBINDEX = AO_USB_IN_EP; + USBCSIL |= USBCSIL_INPKT_RDY; + ao_usb_in_bytes_last = ao_usb_in_bytes; + ao_usb_in_bytes = 0; +} + void ao_usb_flush(void) __critical { - if (ao_usb_in_bytes) { - USBINDEX = AO_USB_IN_EP; - USBCSIL |= USBCSIL_INPKT_RDY; - ao_usb_in_bytes = 0; + if (!ao_usb_running) + return; + + /* If there are pending bytes, or if the last packet was full, + * send another IN packet + */ + if (ao_usb_in_bytes || (ao_usb_in_bytes_last == AO_USB_IN_SIZE)) { + ao_usb_in_wait(); + ao_usb_in_send(); } } @@ -336,18 +364,13 @@ ao_usb_putchar(char c) __critical { if (!ao_usb_running) return; - for (;;) { - USBINDEX = AO_USB_IN_EP; - if ((USBCSIL & USBCSIL_INPKT_RDY) == 0) - break; - ao_sleep(&ao_usb_in_bytes); - } + + ao_usb_in_wait(); + + /* Queue a byte, sending the packet when full */ USBFIFO[AO_USB_IN_EP << 1] = c; - if (++ao_usb_in_bytes == AO_USB_IN_SIZE) { - USBINDEX = AO_USB_IN_EP; - USBCSIL |= USBCSIL_INPKT_RDY; - ao_usb_in_bytes = 0; - } + if (++ao_usb_in_bytes == AO_USB_IN_SIZE) + ao_usb_in_send(); } char |