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Use a different buffer size for Rx and Tx

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The BLE (and USBHID) protocol stores the size of the payload as a single
byte in the packet header. Hence the size of the payload is limited to a
maximum of 255 bytes. For sending packets, there is an additional
command byte present, which reduces the maximum payload size to 254
bytes. For receiving packets, there is no command byte present and thus
the maximum payload size is 255 bytes.

The Scubapro G3 sends BLE packets of 256 bytes, and that caused the
download to fail because the receive buffer was one byte too small.
This commit is contained in:
Jef Driesen 2024-05-15 17:47:34 +02:00
parent 8fe598e1b0
commit eb4b082b1b
1 changed files with 9 additions and 8 deletions
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17
src/uwatec_smart.c
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@ -31,7 +31,8 @@
#define ISINSTANCE(device) dc_device_isinstance((device), &uwatec_smart_device_vtable)
#define DATASIZE 254
#define DATASIZE_RX 255
#define DATASIZE_TX 254
#define PACKETSIZE_USBHID_RX 64
#define PACKETSIZE_USBHID_TX 32
@ -89,13 +90,13 @@ uwatec_smart_irda_send (uwatec_smart_device_t *device, unsigned char cmd, const
dc_status_t rc = DC_STATUS_SUCCESS;
dc_device_t *abstract = (dc_device_t *) device;
if (size > DATASIZE) {
if (size > DATASIZE_TX) {
ERROR (abstract->context, "Command too large (" DC_PRINTF_SIZE ").", size);
return DC_STATUS_PROTOCOL;
}
// Build the packet.
unsigned char packet[1 + DATASIZE] = {
unsigned char packet[1 + DATASIZE_TX] = {
cmd};
if (size) {
memcpy (packet + 1, data, size);
@ -156,13 +157,13 @@ uwatec_smart_serial_send (uwatec_smart_device_t *device, unsigned char cmd, cons
dc_status_t status = DC_STATUS_SUCCESS;
dc_device_t *abstract = (dc_device_t *) device;
if (size > DATASIZE) {
if (size > DATASIZE_TX) {
ERROR (abstract->context, "Command too large (" DC_PRINTF_SIZE ").", size);
return DC_STATUS_PROTOCOL;
}
// Build the packet.
unsigned char packet[12 + DATASIZE + 1] = {
unsigned char packet[12 + DATASIZE_TX + 1] = {
0xFF, 0xFF, 0xFF,
0xA6, 0x59, 0xBD, 0xC2,
size + 1,
@ -276,12 +277,12 @@ uwatec_smart_usbhid_send (uwatec_smart_device_t *device, unsigned char cmd, cons
dc_status_t rc = DC_STATUS_SUCCESS;
dc_device_t *abstract = (dc_device_t *) device;
dc_transport_t transport = dc_iostream_get_transport(device->iostream);
unsigned char buf[DATASIZE + 3];
unsigned char buf[DATASIZE_TX + 3];
size_t packetsize = transport == DC_TRANSPORT_USBHID ?
PACKETSIZE_USBHID_TX + 1 : sizeof(buf);
if (size > DATASIZE || size + 3 > packetsize) {
if (size > DATASIZE_TX || size + 3 > packetsize) {
ERROR (abstract->context, "Command too large (" DC_PRINTF_SIZE ").", size);
return DC_STATUS_INVALIDARGS;
}
@ -315,7 +316,7 @@ uwatec_smart_usbhid_receive (uwatec_smart_device_t *device, dc_event_progress_t
dc_status_t rc = DC_STATUS_SUCCESS;
dc_device_t *abstract = (dc_device_t *) device;
dc_transport_t transport = dc_iostream_get_transport(device->iostream);
unsigned char buf[DATASIZE + 1];
unsigned char buf[DATASIZE_RX + 1];
size_t packetsize = transport == DC_TRANSPORT_USBHID ?
PACKETSIZE_USBHID_RX : sizeof(buf);