Re-implement the set_latency function as an ioctl

The set_latency function is the perfect example of a feature that should
be implemented as an ioctl: it's only implemented by a single driver,
and the functionality is also highly platform specific.

include/libdivecomputer/custom.h

@@ -32,7 +32,6 @@ extern "C" {
 
 typedef struct dc_custom_cbs_t {
 	dc_status_t (*set_timeout) (void *userdata, int timeout);
-	dc_status_t (*set_latency) (void *userdata, unsigned int value);
 	dc_status_t (*set_break) (void *userdata, unsigned int value);
 	dc_status_t (*set_dtr) (void *userdata, unsigned int value);
 	dc_status_t (*set_rts) (void *userdata, unsigned int value);

include/libdivecomputer/iostream.h

@@ -123,22 +123,6 @@ dc_iostream_get_transport (dc_iostream_t *iostream);
 dc_status_t
 dc_iostream_set_timeout (dc_iostream_t *iostream, int timeout);
 
-/**
- * Set the receive latency.
- *
- * The effect of this setting is highly platform and driver specific. On
- * Windows it does nothing at all, on Linux it controls the low latency
- * flag (e.g. only zero vs non-zero latency), and on Mac OS X it sets
- * the receive latency as requested.
- *
- * @param[in]  iostream  A valid I/O stream.
- * @param[in]  value     The latency in milliseconds.
- * @returns #DC_STATUS_SUCCESS on success, or another #dc_status_t code
- * on failure.
- */
-dc_status_t
-dc_iostream_set_latency (dc_iostream_t *iostream, unsigned int value);
-
 /**
  * Set the state of the break condition.
  *

include/libdivecomputer/serial.h

@@ -27,6 +27,7 @@
 #include "iostream.h"
 #include "iterator.h"
 #include "descriptor.h"
+#include "ioctl.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -77,6 +78,16 @@ dc_serial_iterator_new (dc_iterator_t **iterator, dc_context_t *context, dc_desc
 dc_status_t
 dc_serial_open (dc_iostream_t **iostream, dc_context_t *context, const char *name);
 
+/**
+ * Set the receive latency in milliseconds.
+ *
+ * The effect of this setting is highly platform and driver specific. On
+ * Windows it does nothing at all, on Linux it controls the low latency
+ * flag (e.g. only zero vs non-zero latency), and on Mac OS X it sets
+ * the receive latency as requested.
+ */
+#define DC_IOCTL_SERIAL_SET_LATENCY DC_IOCTL_IOW('s', 0, sizeof(unsigned int))
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */

src/bluetooth.c

@@ -99,7 +99,6 @@ static const dc_iterator_vtable_t dc_bluetooth_iterator_vtable = {
 static const dc_iostream_vtable_t dc_bluetooth_vtable = {
 	sizeof(dc_socket_t),
 	dc_socket_set_timeout, /* set_timeout */
-	NULL, /* set_latency */
 	NULL, /* set_break */
 	NULL, /* set_dtr */
 	NULL, /* set_rts */

src/custom.c

@@ -28,7 +28,6 @@
 #include "context-private.h"
 
 static dc_status_t dc_custom_set_timeout (dc_iostream_t *abstract, int timeout);
-static dc_status_t dc_custom_set_latency (dc_iostream_t *abstract, unsigned int value);
 static dc_status_t dc_custom_set_break (dc_iostream_t *abstract, unsigned int value);
 static dc_status_t dc_custom_set_dtr (dc_iostream_t *abstract, unsigned int value);
 static dc_status_t dc_custom_set_rts (dc_iostream_t *abstract, unsigned int value);
@@ -55,7 +54,6 @@ typedef struct dc_custom_t {
 static const dc_iostream_vtable_t dc_custom_vtable = {
 	sizeof(dc_custom_t),
 	dc_custom_set_timeout, /* set_timeout */
-	dc_custom_set_latency, /* set_latency */
 	dc_custom_set_break, /* set_break */
 	dc_custom_set_dtr, /* set_dtr */
 	dc_custom_set_rts, /* set_rts */
@@ -108,17 +106,6 @@ dc_custom_set_timeout (dc_iostream_t *abstract, int timeout)
 	return custom->callbacks.set_timeout (custom->userdata, timeout);
 }
 
-static dc_status_t
-dc_custom_set_latency (dc_iostream_t *abstract, unsigned int value)
-{
-	dc_custom_t *custom = (dc_custom_t *) abstract;
-
-	if (custom->callbacks.set_latency == NULL)
-		return DC_STATUS_SUCCESS;
-
-	return custom->callbacks.set_latency (custom->userdata, value);
-}
-
 static dc_status_t
 dc_custom_set_break (dc_iostream_t *abstract, unsigned int value)
 {

src/iostream-private.h

@@ -43,8 +43,6 @@ struct dc_iostream_vtable_t {
 
 	dc_status_t (*set_timeout) (dc_iostream_t *iostream, int timeout);
 
-	dc_status_t (*set_latency) (dc_iostream_t *iostream, unsigned int value);
-
 	dc_status_t (*set_break) (dc_iostream_t *iostream, unsigned int value);
 
 	dc_status_t (*set_dtr) (dc_iostream_t *iostream, unsigned int value);

src/iostream.c

@@ -87,17 +87,6 @@ dc_iostream_set_timeout (dc_iostream_t *iostream, int timeout)
 	return iostream->vtable->set_timeout (iostream, timeout);
 }
 
-dc_status_t
-dc_iostream_set_latency (dc_iostream_t *iostream, unsigned int value)
-{
-	if (iostream == NULL || iostream->vtable->set_latency == NULL)
-		return DC_STATUS_SUCCESS;
-
-	INFO (iostream->context, "Latency: value=%i", value);
-
-	return iostream->vtable->set_latency (iostream, value);
-}
-
 dc_status_t
 dc_iostream_set_break (dc_iostream_t *iostream, unsigned int value)
 {

src/irda.c

@@ -91,7 +91,6 @@ static const dc_iterator_vtable_t dc_irda_iterator_vtable = {
 static const dc_iostream_vtable_t dc_irda_vtable = {
 	sizeof(dc_socket_t),
 	dc_socket_set_timeout, /* set_timeout */
-	NULL, /* set_latency */
 	NULL, /* set_break */
 	NULL, /* set_dtr */
 	NULL, /* set_rts */

src/libdivecomputer.symbols

@@ -36,7 +36,6 @@ dc_descriptor_get_transports
 
 dc_iostream_get_transport
 dc_iostream_set_timeout
-dc_iostream_set_latency
 dc_iostream_set_break
 dc_iostream_set_dtr
 dc_iostream_set_rts

src/serial_posix.c

@@ -67,7 +67,6 @@ static dc_status_t dc_serial_iterator_next (dc_iterator_t *iterator, void *item)
 static dc_status_t dc_serial_iterator_free (dc_iterator_t *iterator);
 
 static dc_status_t dc_serial_set_timeout (dc_iostream_t *iostream, int timeout);
-static dc_status_t dc_serial_set_latency (dc_iostream_t *iostream, unsigned int value);
 static dc_status_t dc_serial_set_break (dc_iostream_t *iostream, unsigned int value);
 static dc_status_t dc_serial_set_dtr (dc_iostream_t *iostream, unsigned int value);
 static dc_status_t dc_serial_set_rts (dc_iostream_t *iostream, unsigned int value);
@@ -118,7 +117,6 @@ static const dc_iterator_vtable_t dc_serial_iterator_vtable = {
 static const dc_iostream_vtable_t dc_serial_vtable = {
 	sizeof(dc_serial_t),
 	dc_serial_set_timeout, /* set_timeout */
-	dc_serial_set_latency, /* set_latency */
 	dc_serial_set_break, /* set_break */
 	dc_serial_set_dtr, /* set_dtr */
 	dc_serial_set_rts, /* set_rts */
@@ -854,7 +852,12 @@ out:
 static dc_status_t
 dc_serial_ioctl (dc_iostream_t *abstract, unsigned int request, void *data, size_t size)
 {
-	return DC_STATUS_UNSUPPORTED;
+	switch (request) {
+	case DC_IOCTL_SERIAL_SET_LATENCY:
+		return dc_serial_set_latency (abstract, *(unsigned int *) data);
+	default:
+		return DC_STATUS_UNSUPPORTED;
+	}
 }
 
 static dc_status_t

src/serial_win32.c

@@ -36,7 +36,6 @@ static dc_status_t dc_serial_iterator_next (dc_iterator_t *iterator, void *item)
 static dc_status_t dc_serial_iterator_free (dc_iterator_t *iterator);
 
 static dc_status_t dc_serial_set_timeout (dc_iostream_t *iostream, int timeout);
-static dc_status_t dc_serial_set_latency (dc_iostream_t *iostream, unsigned int value);
 static dc_status_t dc_serial_set_break (dc_iostream_t *iostream, unsigned int value);
 static dc_status_t dc_serial_set_dtr (dc_iostream_t *iostream, unsigned int value);
 static dc_status_t dc_serial_set_rts (dc_iostream_t *iostream, unsigned int value);
@@ -93,7 +92,6 @@ static const dc_iterator_vtable_t dc_serial_iterator_vtable = {
 static const dc_iostream_vtable_t dc_serial_vtable = {
 	sizeof(dc_serial_t),
 	dc_serial_set_timeout, /* set_timeout */
-	dc_serial_set_latency, /* set_latency */
 	dc_serial_set_break, /* set_break */
 	dc_serial_set_dtr, /* set_dtr */
 	dc_serial_set_rts, /* set_rts */
@@ -546,12 +544,6 @@ dc_serial_set_timeout (dc_iostream_t *abstract, int timeout)
 	return DC_STATUS_SUCCESS;
 }
 
-static dc_status_t
-dc_serial_set_latency (dc_iostream_t *abstract, unsigned int value)
-{
-	return DC_STATUS_SUCCESS;
-}
-
 static dc_status_t
 dc_serial_poll (dc_iostream_t *abstract, int timeout)
 {
@@ -687,7 +679,12 @@ out:
 static dc_status_t
 dc_serial_ioctl (dc_iostream_t *abstract, unsigned int request, void *data, size_t size)
 {
-	return DC_STATUS_UNSUPPORTED;
+	switch (request) {
+	case DC_IOCTL_SERIAL_SET_LATENCY:
+		return DC_STATUS_SUCCESS;
+	default:
+		return DC_STATUS_UNSUPPORTED;
+	}
 }
 
 static dc_status_t

src/usbhid.c

@@ -139,7 +139,6 @@ static const dc_iterator_vtable_t dc_usbhid_iterator_vtable = {
 static const dc_iostream_vtable_t dc_usbhid_vtable = {
 	sizeof(dc_usbhid_t),
 	dc_usbhid_set_timeout, /* set_timeout */
-	NULL, /* set_latency */
 	NULL, /* set_break */
 	NULL, /* set_dtr */
 	NULL, /* set_rts */