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Handle the half-duplex emulation in the vyper2 backend

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The half-duplex emulation is basically a workaround for a timing problem
in the vyper2 backend. Since no other dive computer backend uses or
needs this feature, it makes no sense to support this at the I/O layer.
It can be implemented directly in the vyper2 backend instead.
This commit is contained in:
Jef Driesen 2018-02-24 09:16:23 +01:00
parent ee31f24cfb
commit 4897a8351b
1 changed files with 49 additions and 8 deletions
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57
src/suunto_vyper2.c
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@ -28,6 +28,7 @@
#include "serial.h"
#include "checksum.h"
#include "array.h"
#include "timer.h"
#define ISINSTANCE(device) dc_device_isinstance((device), (const dc_device_vtable_t *) &suunto_vyper2_device_vtable)
@ -36,6 +37,7 @@
typedef struct suunto_vyper2_device_t {
suunto_common2_device_t base;
dc_iostream_t *iostream;
dc_timer_t *timer;
} suunto_vyper2_device_t;
static dc_status_t suunto_vyper2_device_packet (dc_device_t *abstract, const unsigned char command[], unsigned int csize, unsigned char answer[], unsigned int asize, unsigned int size);
@ -95,11 +97,18 @@ suunto_vyper2_device_open (dc_device_t **out, dc_context_t *context, const char
// Set the default values.
device->iostream = NULL;
// Create a high resolution timer.
status = dc_timer_new (&device->timer);
if (status != DC_STATUS_SUCCESS) {
ERROR (context, "Failed to create a high resolution timer.");
goto error_free;
}
// Open the device.
status = dc_serial_open (&device->iostream, context, name);
if (status != DC_STATUS_SUCCESS) {
ERROR (context, "Failed to open the serial port.");
goto error_free;
goto error_timer_free;
}
// Set the serial communication protocol (9600 8N1).
@ -133,13 +142,6 @@ suunto_vyper2_device_open (dc_device_t **out, dc_context_t *context, const char
goto error_close;
}
// Enable half-duplex emulation.
status = dc_iostream_set_halfduplex (device->iostream, 1);
if (status != DC_STATUS_SUCCESS) {
ERROR (context, "Failed to set half duplex.");
goto error_close;
}
// Read the version info.
status = suunto_common2_device_version ((dc_device_t *) device, device->base.version, sizeof (device->base.version));
if (status != DC_STATUS_SUCCESS) {
@ -160,6 +162,8 @@ suunto_vyper2_device_open (dc_device_t **out, dc_context_t *context, const char
error_close:
dc_iostream_close (device->iostream);
error_timer_free:
dc_timer_free (device->timer);
error_free:
dc_device_deallocate ((dc_device_t *) device);
return status;
@ -173,6 +177,8 @@ suunto_vyper2_device_close (dc_device_t *abstract)
suunto_vyper2_device_t *device = (suunto_vyper2_device_t*) abstract;
dc_status_t rc = DC_STATUS_SUCCESS;
dc_timer_free (device->timer);
// Close the device.
rc = dc_iostream_close (device->iostream);
if (rc != DC_STATUS_SUCCESS) {
@ -201,6 +207,13 @@ suunto_vyper2_device_packet (dc_device_t *abstract, const unsigned char command[
return status;
}
// Get the current timestamp.
dc_usecs_t begin = 0;
status = dc_timer_now (device->timer, &begin);
if (status != DC_STATUS_SUCCESS) {
return status;
}
// Send the command to the dive computer.
status = dc_iostream_write (device->iostream, command, csize, NULL);
if (status != DC_STATUS_SUCCESS) {
@ -208,6 +221,34 @@ suunto_vyper2_device_packet (dc_device_t *abstract, const unsigned char command[
return status;
}
// Get the current timestamp.
dc_usecs_t end = 0;
status = dc_timer_now (device->timer, &end);
if (status != DC_STATUS_SUCCESS) {
return status;
}
// Calculate the elapsed time.
dc_usecs_t elapsed = end - begin;
// Calculate the expected duration. A 2 millisecond fudge factor is added
// because it improves the success rate significantly.
unsigned int baudrate = 9600;
unsigned int nbits = 1 + 8 /* databits */ + 1 /* stopbits */ + 0 /* parity */;
dc_usecs_t expected = (dc_usecs_t) csize * 1000000 * nbits / baudrate + 2000;
// Wait for the remaining time.
if (elapsed < expected) {
dc_usecs_t remaining = expected - elapsed;
// The remaining time is rounded up to the nearest millisecond
// because the sleep function doesn't support a higher
// resolution on all platforms. The higher resolution is
// pointless anyway, since we already added a fudge factor
// above.
dc_iostream_sleep (device->iostream, (remaining + 999) / 1000);
}
// Clear RTS to receive the reply.
status = dc_iostream_set_rts (device->iostream, 0);
if (status != DC_STATUS_SUCCESS) {