usb: improve ms compatible ID and function name string handling

Signed-off-by: Benedek Kupper <kupper.benedek@gmail.com>

Author: benedekkupper

c2usb/usb/df/class/cdc.cpp

@@ -39,7 +39,7 @@ function::get_base_functional_descriptors(class_info cinfo, uint8_t if_index, df
     };
     auto* descs = buffer.allocate<desc_set>(cinfo, if_index);
 
-    descs->if_assoc.iFunction = descs->iface.iInterface = to_istring(0);
+    descs->if_assoc.iFunction = descs->iface.iInterface = name_istring();
 
     return &descs->iface;
 }

c2usb/usb/df/class/hid.cpp

@@ -113,9 +113,9 @@ void function::describe_config(const config::interface& iface, uint8_t if_index,
 
     iface_desc->bInterfaceNumber = if_index;
     iface_desc->bInterfaceClass = CLASS_CODE;
-    iface_desc->bInterfaceSubClass = protocol_ != boot_protocol_mode::NONE;
-    iface_desc->bInterfaceProtocol = static_cast<uint8_t>(protocol_);
-    iface_desc->iInterface = to_istring(0);
+    iface_desc->bInterfaceSubClass = protocol_mode() != boot_protocol_mode::NONE;
+    iface_desc->bInterfaceProtocol = static_cast<uint8_t>(protocol_mode());
+    iface_desc->iInterface = name_istring();
     iface_desc->bNumEndpoints = describe_endpoints(iface, buffer);
     assert((iface.endpoints()[0].address().direction() == direction::IN) and
            ((1 == iface_desc->bNumEndpoints) or

c2usb/usb/df/class/hid.hpp

@@ -70,6 +70,7 @@ class function : public app_base_function
     void control_setup_request(message& msg, const config::interface& iface) override;
     void control_data_complete(message& msg, const config::interface& iface) override;
 
+    boot_protocol_mode protocol_mode() const { return protocol_; }
     const boot_protocol_mode protocol_;
 };
 

c2usb/usb/df/function.hpp

@@ -49,7 +49,7 @@ class function : public polymorphic
     void init(const config::interface& iface, mac* m);
     void deinit(const config::interface& iface);
 
-    virtual const char* ms_compatible_id() const { return nullptr; }
+    virtual std::string_view ms_compatible_id() const { return {}; }
 
     virtual void transfer_complete([[maybe_unused]] ep_handle eph,
                                    [[maybe_unused]] const transfer& t)
@@ -93,7 +93,10 @@ class function : public polymorphic
 
     virtual void send_string(uint8_t rel_index, string_message& smsg);
 
-    virtual uint8_t get_alt_setting([[maybe_unused]] const config::interface& iface) { return 0; }
+    virtual uint8_t get_alt_setting([[maybe_unused]] const config::interface& iface) const
+    {
+        return 0;
+    }
 
     virtual void enable([[maybe_unused]] const config::interface& iface,
                         [[maybe_unused]] uint8_t alt_sel)
@@ -138,6 +141,8 @@ class named_function : public function
 
     void send_string(uint8_t rel_index, string_message& smsg) override;
 
+    istring name_istring() const { return (name_ != nullptr) ? to_istring(0) : 0; }
+
   private:
     const char_t* const name_{};
 };

c2usb/usb/df/vendor/microsoft/os_extension.cpp

@@ -17,17 +17,16 @@ void descriptors::get_msos2_function_subset(const config::interface& iface, uint
                                             df::buffer& buffer)
 {
     // the only interesting thing is the compatible ID
-    auto* compat_id = iface.function().ms_compatible_id();
-    if (compat_id == nullptr)
+    auto compat_id = iface.function().ms_compatible_id();
+    if (compat_id.empty())
     {
         return;
     }
     auto* func_header = buffer.allocate<usb::microsoft::function_subset_header>();
     func_header->bFirstInterface = iface_index;
 
     auto* comp_id_desc = buffer.allocate<usb::microsoft::compatible_id>();
-    std::string_view(compat_id).copy(comp_id_desc->CompatibleID,
-                                     sizeof(comp_id_desc->CompatibleID));
+    compat_id.copy(comp_id_desc->CompatibleID, sizeof(comp_id_desc->CompatibleID));
 
     // When finished with the contents, save the total size of the subset
     func_header->wSubsetLength =

c2usb/usb/df/vendor/microsoft/xinput.cpp

@@ -29,7 +29,7 @@ void xfunction::describe_config(const config::interface& iface, uint8_t if_index
     iface_desc->bInterfaceClass = xusb::CLASS_CODE;
     iface_desc->bInterfaceSubClass = xusb::SUBCLASS_CODE;
     iface_desc->bInterfaceProtocol = xusb::PROTOCOL_CODE;
-    iface_desc->iInterface = to_istring(0);
+    iface_desc->iInterface = name_istring();
     iface_desc->bNumEndpoints = describe_endpoints(iface, buffer);
     assert((iface_desc->bNumEndpoints == 2) and
            (iface.endpoints()[0].address().direction() == direction::IN) and

c2usb/usb/df/vendor/microsoft/xinput.hpp

@@ -33,7 +33,10 @@ class xfunction : public df::hid::app_base_function
     void describe_config(const config::interface& iface, uint8_t if_index,
                          df::buffer& buffer) override;
 
-    const char* ms_compatible_id() const override { return usb::microsoft::xusb::COMPATIBLE_ID; }
+    std::string_view ms_compatible_id() const override
+    {
+        return usb::microsoft::xusb::COMPATIBLE_ID;
+    }
 
     void enable(const config::interface& iface, uint8_t alt_sel) override;
 };

c2usb/usb/vendor/microsoft_xusb.hpp

@@ -31,7 +31,7 @@ inline namespace xusb22
     "GamepadStickUsage"=dword:31303532
 */
 
-constexpr const char* COMPATIBLE_ID = "XUSB20";
+constexpr std::string_view COMPATIBLE_ID{"XUSB20"};
 
 constexpr uint8_t CLASS_CODE = 0xFF;
 constexpr uint8_t SUBCLASS_CODE = 0x5D;