Equivalent for $DISPLAY

index 12e6f33..1810cb5 100644

2 files changed, 87 insertions, 37 deletions

diff --git a/src/libdlo.c b/src/libdlo.c
index 12e6f33..eef7719 100644
--- a/src/libdlo.c
+++ b/src/libdlo.c
@@ -464,27 +464,68 @@ error:
   DPRINTF("dlo: claim: error %u '%s'\n", (int)err, dlo_strerror(err));

 

   return (dlo_dev_t)0;

-}

-

-

-dlo_dev_t dlo_claim_first_device(const dlo_claim_t flags, const uint32_t timeout)

-{

-  dlo_devlist_t *node;

-  dlo_devlist_t *next;

-  dlo_dev_t      uid = 0;

+}
+
+
+static const char* parse_cmdline(int *argc_p, char *argv[])
+{
+  /* Scan the command line looking for --dlo:display.  Return the value found, if
+   * any, else return NULL.  Remove all --dlo:* options from argv.
+   */
+
+  const char *display = NULL;
+  int n;
+  int m = 1;
+
+  if (!argc_p) {
+    return NULL;
+  }
+
+  for (n=1; n<*argc_p; ++n) {
+    const char* arg = argv[n];
+    if (strncmp(arg,"--dlo:",6)==0) {
+      const char* dlo_arg = arg + 6;
+      if (strncmp(dlo_arg,"display=",8)==0) {
+        display = dlo_arg + 8;
+      }
+    } else {
+      argv[m] = arg;
+      ++m;
+    }
+  }
+  *argc_p = m;
+  return display;
+}
+
+dlo_dev_t dlo_claim_default_device(int *argc_p, char *argv[],
+                                   const dlo_claim_t flags, const uint32_t timeout)
+{
+  const char *display = parse_cmdline(argc_p, argv);
+  if (!display) {
+    display = getenv("DLODISPLAY");
+  }
+
+  // For now, assume that display is simply the serial number.  Some thought about
+  // exactly what its format should be is needed.
+  const char *serial = display;
+
+  dlo_devlist_t *node;
+  dlo_devlist_t *next;
+  dlo_dev_t      uid = 0;
 

   /* Look for a DisplayLink device to connect to - note the first one which is unclaimed */

   node = dlo_enumerate_devices();

   

   // dlo_enumerate_devices allocates memory for each node, which we must free

   while (node)

-  {

-    dlo_device_t *dev = (dlo_device_t *)node->dev.uid;

-

-    if (!uid && !dev->claimed)

-    {

-      uid = dlo_claim_device(node->dev.uid, flags, timeout);

-    }

+  {
+    dlo_device_t *dev = (dlo_device_t *)node->dev.uid;
+
+    if (!uid && !dev->claimed
+        && (!serial || strcmp(serial,dev->serial)==0))
+    {
+      uid = dlo_claim_device(node->dev.uid, flags, timeout);
+    }
 

     /* If we haven't claimed a device, move on to the next one */

     next = node->next;

diff --git a/src/libdlo.h b/src/libdlo.h
index f6b5f0a..286cc88 100644
--- a/src/libdlo.h
+++ b/src/libdlo.h
@@ -601,28 +601,37 @@ extern dlo_devlist_t *dlo_enumerate_devices(void);
  *  Devices should be released with a call to @c release_device() when they are no

  *  longer required.

  */

-extern dlo_dev_t dlo_claim_device(const dlo_dev_t uid, const dlo_claim_t flags, const uint32_t timeout);

-

-

-/** Claim the first available (unclaimed) device.

- *

- *  @param  flags    Flags word describing how the device is to be accessed.

- *  @param  timeout  Timeout in milliseconds (zero for infinite).

- *

- *  @return  Unique ID of the claimed device (or NULL if failed).

- *

- *  This call performs a very similar function to @c dlo_claim_device() except

- *  that it performs the enumeration of connected devices on behalf of the caller

- *  and returns the unique ID of the first available (unclaimed device). This

- *  device is claimed automatically.

- *

- *  If no unclaimed devices are found, or if the claim operation itself fails in

- *  some way, the function will return a device handle of zero.

- */

-extern dlo_dev_t dlo_claim_first_device(const dlo_claim_t flags, const uint32_t timeout);

-

-

-/** Release the specified device.

+extern dlo_dev_t dlo_claim_device(const dlo_dev_t uid, const dlo_claim_t flags, const uint32_t timeout);
+
+
+/** Claim the default device.
+ *
+ *  @param  argc_p   Pointer to main program's argc.
+ *  @param  argv     Main program's argv.
+ *  @param  flags    Flags word describing how the device is to be accessed.
+ *  @param  timeout  Timeout in milliseconds (zero for infinite).
+ *
+ *  @return  Unique ID of the claimed device (or NULL if failed).
+ *
+ *  This call enumerates the connected devices and returns the unique ID of the default
+ *  device.  The default device is selected by the DLODISPLAY environment variable or the
+ *  --dlo:display command-line option; if neither is specified the first device found is
+ *  selected.  This selected device is claimed.
+ *
+ *  If no default device is found, or if the claim operation fails, the function will
+ *  return a device handle of zero.
+ *
+ *  The main program should pass a pointer to argc and argv to this function so that any
+ *  --dlo:display option can be found.  This function will update argc and argv to remove
+ *  any --dlo:* options that it finds, so the main program need not worry about the
+ *  presence of these options in the command line if it calls this function first.
+ *  Pass NULL as argc_p to disable command-line parsing.
+ */
+extern dlo_dev_t dlo_claim_default_device(int *argc_p, char *argv[],
+                                          const dlo_claim_t flags, const uint32_t timeout);
+
+
+/** Release the specified device.
  *

  *  @param  uid  Unique ID of the device to release.

  *