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Read the entire data packet in a single operation

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Refactor the packet receiving code to read the ack byte, the payload
data and the checksum all at once, with just a single read operation.
This is not only a bit more efficient, but will also simplify the BLE
support.
This commit is contained in:
Jef Driesen 2019-02-01 15:53:14 +01:00
parent 437db813d5
commit 4923d3761e
1 changed files with 22 additions and 23 deletions
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45
src/oceanic_atom2.c
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@ -38,6 +38,7 @@
#define I770R 0x4651
#define GEO40 0x4653
#define MAXPACKET 256
#define MAXRETRIES 2
#define MAXDELAY 16
#define INVALID 0xFFFFFFFF
@ -539,6 +540,14 @@ oceanic_atom2_packet (oceanic_atom2_device_t *device, const unsigned char comman
dc_status_t status = DC_STATUS_SUCCESS;
dc_device_t *abstract = (dc_device_t *) device;
if (asize > MAXPACKET) {
return DC_STATUS_INVALIDARGS;
}
if (crc_size > 2 || (crc_size != 0 && asize == 0)) {
return DC_STATUS_INVALIDARGS;
}
if (device_is_cancelled (abstract))
return DC_STATUS_CANCELLED;
@ -553,41 +562,36 @@ oceanic_atom2_packet (oceanic_atom2_device_t *device, const unsigned char comman
return status;
}
// Receive the response (ACK/NAK) of the dive computer.
unsigned char response = 0;
status = dc_iostream_read (device->iostream, &response, 1, NULL);
// Receive the answer of the dive computer.
unsigned char packet[1 + MAXPACKET + 2];
status = dc_iostream_read (device->iostream, packet, 1 + asize + crc_size, NULL);
if (status != DC_STATUS_SUCCESS) {
ERROR (abstract->context, "Failed to receive the answer.");
return status;
}
// Verify the response of the dive computer.
if (response != ack) {
// Verify the ACK byte of the answer.
if (packet[0] != ack) {
ERROR (abstract->context, "Unexpected answer start byte(s).");
return DC_STATUS_PROTOCOL;
}
if (asize) {
// Receive the answer of the dive computer.
status = dc_iostream_read (device->iostream, answer, asize, NULL);
if (status != DC_STATUS_SUCCESS) {
ERROR (abstract->context, "Failed to receive the answer.");
return status;
}
// Verify the checksum of the answer.
unsigned short crc, ccrc;
if (crc_size == 2) {
crc = array_uint16_le (answer + asize - 2);
ccrc = checksum_add_uint16 (answer, asize - 2, 0x0000);
crc = array_uint16_le (packet + 1 + asize);
ccrc = checksum_add_uint16 (packet + 1, asize, 0x0000);
} else {
crc = answer[asize - 1];
ccrc = checksum_add_uint8 (answer, asize - 1, 0x00);
crc = packet[1 + asize];
ccrc = checksum_add_uint8 (packet + 1, asize, 0x00);
}
if (crc != ccrc) {
ERROR (abstract->context, "Unexpected answer checksum.");
return DC_STATUS_PROTOCOL;
}
memcpy (answer, packet + 1, asize);
}
return DC_STATUS_SUCCESS;
@ -847,14 +851,11 @@ oceanic_atom2_device_version (dc_device_t *abstract, unsigned char data[], unsig
if (size < PAGESIZE)
return DC_STATUS_INVALIDARGS;
unsigned char answer[PAGESIZE + 1] = {0};
unsigned char command[] = {CMD_VERSION};
dc_status_t rc = oceanic_atom2_transfer (device, command, sizeof (command), ACK, answer, sizeof (answer), 1);
dc_status_t rc = oceanic_atom2_transfer (device, command, sizeof (command), ACK, data, PAGESIZE, 1);
if (rc != DC_STATUS_SUCCESS)
return rc;
memcpy (data, answer, PAGESIZE);
return DC_STATUS_SUCCESS;
}
@ -912,17 +913,15 @@ oceanic_atom2_device_read (dc_device_t *abstract, unsigned int address, unsigned
if (page != device->cached_page || highmem != device->cached_highmem) {
// Read the package.
unsigned int number = highmem ? page : page * device->bigpage; // This is always PAGESIZE, even in big page mode.
unsigned char answer[256 + 2] = {0}; // Maximum we support for the known commands.
unsigned char command[] = {read_cmd,
(number >> 8) & 0xFF, // high
(number ) & 0xFF, // low
};
dc_status_t rc = oceanic_atom2_transfer (device, command, sizeof (command), ACK, answer, pagesize + crc_size, crc_size);
dc_status_t rc = oceanic_atom2_transfer (device, command, sizeof (command), ACK, device->cache, pagesize, crc_size);
if (rc != DC_STATUS_SUCCESS)
return rc;
// Cache the page.
memcpy (device->cache, answer, pagesize);
device->cached_page = page;
device->cached_highmem = highmem;
}