third_party/NordicSemiconductor/libraries/usb/app_usbd_string_desc.c - third_party/openthread - Git at Google

 /**
  * Copyright (c) 2016 - 2019, Nordic Semiconductor ASA
  *
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice, this
  *    list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form, except as embedded into a Nordic
  *    Semiconductor ASA integrated circuit in a product or a software update for
  *    such product, must reproduce the above copyright notice, this list of
  *    conditions and the following disclaimer in the documentation and/or other
  *    materials provided with the distribution.
  *
  * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
  *    contributors may be used to endorse or promote products derived from this
  *    software without specific prior written permission.
  *
  * 4. This software, with or without modification, must only be used with a
  *    Nordic Semiconductor ASA integrated circuit.
  *
  * 5. Any software provided in binary form under this license must not be reverse
  *    engineered, decompiled, modified and/or disassembled.
  *
  * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */
 #include "sdk_config.h"
 #if APP_USBD_ENABLED
 #include "app_usbd_string_desc.h"
 #include "app_usbd_langid.h"
 #include "app_usbd_core.h"
 #include "nordic_common.h"
 #include "utf.h"

 /**
  * @defgroup app_usbd_string_desc
  * @ingroup app_usbd
  *
  * USBD string descriptor management
  * @{
  */

 /**
  * @brief Array with language identifiers.
  *
  * This array is used to search the proper string for the selected language.
  */
 static uint16_t const m_langids[] = { APP_USBD_STRINGS_LANGIDS };

 /**
  * @brief Language ID descriptor.
  *
  * Language.
  */


 /**
  * @brief Mnemonics for the string positions in the array.
  *
  * The mnemonics for the indexes of the strings inside the string array.
  */
 enum {
     APP_USBD_STRING_ID_LANGIDS_ARRAY_POS = 0,  /**< Supported language identifiers. */

 #if (APP_USBD_STRING_ID_MANUFACTURER != 0)
     APP_USBD_STRING_ID_MANUFACTURER_ARRAY_POS, /**< Manufacturer name. */
 #endif // (APP_USBD_STRING_ID_MANUFACTURER != 0)

 #if (APP_USBD_STRING_ID_PRODUCT != 0)
     APP_USBD_STRING_ID_PRODUCT_ARRAY_POS, /**< Product name. */
 #endif // (APP_USBD_STRING_ID_PRODUCT != 0)

 #if (APP_USBD_STRING_ID_SERIAL != 0)
     APP_USBD_STRING_ID_SERIAL_ARRAY_POS, /**<  Serial number. */
 #endif // (APP_USBD_STRING_ID_SERIAL != 0)

 #if (APP_USBD_STRING_ID_CONFIGURATION != 0)
     APP_USBD_STRING_ID_CONFIGURATION_ARRAY_POS, /**< Configuration string. */
 #endif // (APP_USBD_STRING_ID_CONFIGURATION != 0)

 #define X(mnemonic, str_idx, ...) CONCAT_2(mnemonic, _ARRAY_POS),
     APP_USBD_STRINGS_USER
 #undef X
 };

 /**
  * @brief String index into internal array index conversion table.
  *
  * The array that transforms the USB string indexes into internal array position.
  * @note Value 0 is used to mark non-existing string.
  */
 static uint8_t const m_string_translation[APP_USBD_STRING_ID_CNT] =
 {
     [APP_USBD_STRING_ID_LANGIDS] = APP_USBD_STRING_ID_LANGIDS_ARRAY_POS,

 #if (APP_USBD_STRING_ID_MANUFACTURER != 0)
     [APP_USBD_STRING_ID_MANUFACTURER] = APP_USBD_STRING_ID_MANUFACTURER_ARRAY_POS,
 #endif // (APP_USBD_STRING_ID_MANUFACTURER != 0)

 #if (APP_USBD_STRING_ID_PRODUCT != 0)
     [APP_USBD_STRING_ID_PRODUCT] = APP_USBD_STRING_ID_PRODUCT_ARRAY_POS,
 #endif // (APP_USBD_STRING_ID_PRODUCT != 0)

 #if (APP_USBD_STRING_ID_SERIAL != 0)
     [APP_USBD_STRING_ID_SERIAL] = APP_USBD_STRING_ID_SERIAL_ARRAY_POS,
 #endif // (APP_USBD_STRING_ID_SERIAL != 0)

 #if (APP_USBD_STRING_ID_CONFIGURATION != 0)
     [APP_USBD_STRING_ID_CONFIGURATION] = APP_USBD_STRING_ID_CONFIGURATION_ARRAY_POS,
 #endif // (APP_USBD_STRING_ID_CONFIGURATION != 0)

 #define X(mnemonic, str_idx, ...) [mnemonic] = CONCAT_2(mnemonic, _ARRAY_POS),
     APP_USBD_STRINGS_USER
 #undef X
 };

 #ifndef APP_USBD_STRINGS_MANUFACTURER_EXTERN
 #define APP_USBD_STRINGS_MANUFACTURER_EXTERN 0
 #endif

 #if APP_USBD_STRINGS_MANUFACTURER_EXTERN
 extern uint8_t APP_USBD_STRINGS_MANUFACTURER[];
 #endif

 #ifndef APP_USBD_STRINGS_PRODUCT_EXTERN
 #define APP_USBD_STRINGS_PRODUCT_EXTERN 0
 #endif

 #if APP_USBD_STRINGS_PRODUCT_EXTERN
 extern uint8_t APP_USBD_STRINGS_PRODUCT[];
 #endif

 #ifndef APP_USBD_STRING_SERIAL_EXTERN
 #define APP_USBD_STRING_SERIAL_EXTERN 0
 #endif

 #if APP_USBD_STRING_SERIAL_EXTERN
 extern uint8_t APP_USBD_STRING_SERIAL[];
 #endif

 #ifndef APP_USBD_STRING_CONFIGURATION_EXTERN
 #define APP_USBD_STRING_CONFIGURATION_EXTERN 0
 #endif

 #if APP_USBD_STRING_CONFIGURATION_EXTERN
 extern uint8_t APP_USBD_STRING_CONFIGURATION[];
 #endif

 /**
  * @brief String descriptor table.
  * */
 static uint8_t const * m_string_dsc[APP_USBD_STRING_ID_CNT][ARRAY_SIZE(m_langids)] =
 {
     [APP_USBD_STRING_ID_LANGIDS_ARRAY_POS] = {APP_USBD_STRING_RAW16_DESC(APP_USBD_STRINGS_LANGIDS)},

 #if (APP_USBD_STRING_ID_MANUFACTURER != 0)
     [APP_USBD_STRING_ID_MANUFACTURER_ARRAY_POS] = { APP_USBD_STRINGS_MANUFACTURER },
 #endif // (APP_USBD_STRING_ID_MANUFACTURER != 0)

 #if (APP_USBD_STRING_ID_PRODUCT != 0)
     [APP_USBD_STRING_ID_PRODUCT_ARRAY_POS] = { APP_USBD_STRINGS_PRODUCT },
 #endif // (APP_USBD_STRING_ID_PRODUCT != 0)

 #if (APP_USBD_STRING_ID_SERIAL != 0)
     [APP_USBD_STRING_ID_SERIAL_ARRAY_POS] = { APP_USBD_STRING_SERIAL },
 #endif // (APP_USBD_STRING_ID_SERIAL != 0)

 #if (APP_USBD_STRING_ID_CONFIGURATION != 0)
     [APP_USBD_STRING_ID_CONFIGURATION_ARRAY_POS] = { APP_USBD_STRINGS_CONFIGURATION },
 #endif // (APP_USBD_STRING_ID_CONFIGURATION != 0)

 #define X(mnemonic, str_idx, ...) [CONCAT_2(mnemonic, _ARRAY_POS)] = {__VA_ARGS__},
     APP_USBD_STRINGS_USER
 #undef X
 };

 /**
  * @brief Function for preparing UTF16 string descriptor.
  *
  * @param idx    String descriptor ID.
  * @param langid Language ID.
  *
  * @return Pointer to the string descriptor.
  */
 static uint16_t * app_usbd_prepare_string(uint8_t idx, uint16_t langid)
 {
     if (m_string_dsc[idx][langid][0] == 0x00)
     {
         return (uint16_t *) &(m_string_dsc[idx][langid][2]);
     }

 #if ((APP_USBD_CONFIG_DESC_STRING_SIZE * 2) + 2) <= NRF_DRV_USBD_EPSIZE
     uint16_t * string_buffer = app_usbd_core_setup_transfer_buff_get(NULL);
 #else
     static uint16_t string_buffer[APP_USBD_CONFIG_DESC_STRING_SIZE + 1];
     // + 1 element for string descriptor type and size
 #endif

     uint8_t         size  = 0;
     const uint8_t * p_pos = m_string_dsc[idx][langid];

 #if APP_USBD_CONFIG_DESC_STRING_UTF_ENABLED
     size = utf8UTF16Count((char *) p_pos, 0);
     ASSERT(size <= APP_USBD_CONFIG_DESC_STRING_SIZE);

     uint16_t * p_out = &(string_buffer[1]);
     uint32_t   rune;

     while (*p_pos != 0)
     {
         p_pos = (uint8_t *) utf8DecodeRune((char *) p_pos, 0, &rune);
         p_out += utf16EncodeRune(rune, p_out);
     }
 #else
     while(*p_pos != 0)
     {
         ASSERT(size < APP_USBD_CONFIG_DESC_STRING_SIZE);
         ++size;
         string_buffer[size] = *p_pos;
         ++p_pos;
     }
 #endif

     // Descriptor size is length of the string times 2 bytes per character + 2 bytes for
     // descriptor type and size.
     string_buffer[0] = (0xff & (size * 2 + 2)) | ((uint16_t)APP_USBD_DESCRIPTOR_STRING) << 8;

     return string_buffer;
 }

 uint16_t const * app_usbd_string_desc_get(uint8_t idx, uint16_t langid)
 {
     /* LANGID string. */
     if (APP_USBD_STRING_ID_LANGIDS == idx)
     {
         return app_usbd_prepare_string(APP_USBD_STRING_ID_LANGIDS_ARRAY_POS, 0);
     }

     /* Searching for the language. */
     uint8_t lang_idx = 0;
     if (ARRAY_SIZE(m_langids) > 1)
     {
         while (m_langids[lang_idx] != langid)
         {
             ++lang_idx;
             if (lang_idx >= ARRAY_SIZE(m_langids))
             {
                 return NULL;
             }
         }
     }

     /* Get the string index in array. */
     if (idx >= ARRAY_SIZE(m_string_translation))
     {
         return NULL;
     }

     uint8_t str_pos = m_string_translation[idx];
     if (str_pos == 0)
     {
         return NULL;
     }

     if ((ARRAY_SIZE(m_langids) > 1) && (lang_idx != 0))
     {
         if (m_string_dsc[str_pos][lang_idx] == NULL)
         {
             lang_idx = 0;
         }
     }

     if (m_string_dsc[str_pos][lang_idx] == NULL)
     {
         return NULL;
     }

     return app_usbd_prepare_string(str_pos, lang_idx);
 }

 /** @} */
 #endif // APP_USBD_ENABLED
	/**
	* Copyright (c) 2016 - 2019, Nordic Semiconductor ASA
	*
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without modification,
	* are permitted provided that the following conditions are met:
	*
	* 1. Redistributions of source code must retain the above copyright notice, this
	* list of conditions and the following disclaimer.
	*
	* 2. Redistributions in binary form, except as embedded into a Nordic
	* Semiconductor ASA integrated circuit in a product or a software update for
	* such product, must reproduce the above copyright notice, this list of
	* conditions and the following disclaimer in the documentation and/or other
	* materials provided with the distribution.
	*
	* 3. Neither the name of Nordic Semiconductor ASA nor the names of its
	* contributors may be used to endorse or promote products derived from this
	* software without specific prior written permission.
	*
	* 4. This software, with or without modification, must only be used with a
	* Nordic Semiconductor ASA integrated circuit.
	*
	* 5. Any software provided in binary form under this license must not be reverse
	* engineered, decompiled, modified and/or disassembled.
	*
	* THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
	* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
	* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
	* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	*/
	#include "sdk_config.h"
	#if APP_USBD_ENABLED
	#include "app_usbd_string_desc.h"
	#include "app_usbd_langid.h"
	#include "app_usbd_core.h"
	#include "nordic_common.h"
	#include "utf.h"

	/**
	* @defgroup app_usbd_string_desc
	* @ingroup app_usbd
	*
	* USBD string descriptor management
	* @{
	*/

	/**
	* @brief Array with language identifiers.
	*
	* This array is used to search the proper string for the selected language.
	*/
	static uint16_t const m_langids[] = { APP_USBD_STRINGS_LANGIDS };

	/**
	* @brief Language ID descriptor.
	*
	* Language.
	*/


	/**
	* @brief Mnemonics for the string positions in the array.
	*
	* The mnemonics for the indexes of the strings inside the string array.
	*/
	enum {
	APP_USBD_STRING_ID_LANGIDS_ARRAY_POS = 0, /*< Supported language identifiers. /

	#if (APP_USBD_STRING_ID_MANUFACTURER != 0)
	APP_USBD_STRING_ID_MANUFACTURER_ARRAY_POS, /*< Manufacturer name. /
	#endif // (APP_USBD_STRING_ID_MANUFACTURER != 0)

	#if (APP_USBD_STRING_ID_PRODUCT != 0)
	APP_USBD_STRING_ID_PRODUCT_ARRAY_POS, /*< Product name. /
	#endif // (APP_USBD_STRING_ID_PRODUCT != 0)

	#if (APP_USBD_STRING_ID_SERIAL != 0)
	APP_USBD_STRING_ID_SERIAL_ARRAY_POS, /*< Serial number. /
	#endif // (APP_USBD_STRING_ID_SERIAL != 0)

	#if (APP_USBD_STRING_ID_CONFIGURATION != 0)
	APP_USBD_STRING_ID_CONFIGURATION_ARRAY_POS, /*< Configuration string. /
	#endif // (APP_USBD_STRING_ID_CONFIGURATION != 0)

	#define X(mnemonic, str_idx, ...) CONCAT_2(mnemonic, _ARRAY_POS),
	APP_USBD_STRINGS_USER
	#undef X
	};

	/**
	* @brief String index into internal array index conversion table.
	*
	* The array that transforms the USB string indexes into internal array position.
	* @note Value 0 is used to mark non-existing string.
	*/
	static uint8_t const m_string_translation[APP_USBD_STRING_ID_CNT] =
	{
	[APP_USBD_STRING_ID_LANGIDS] = APP_USBD_STRING_ID_LANGIDS_ARRAY_POS,

	#if (APP_USBD_STRING_ID_MANUFACTURER != 0)
	[APP_USBD_STRING_ID_MANUFACTURER] = APP_USBD_STRING_ID_MANUFACTURER_ARRAY_POS,
	#endif // (APP_USBD_STRING_ID_MANUFACTURER != 0)

	#if (APP_USBD_STRING_ID_PRODUCT != 0)
	[APP_USBD_STRING_ID_PRODUCT] = APP_USBD_STRING_ID_PRODUCT_ARRAY_POS,
	#endif // (APP_USBD_STRING_ID_PRODUCT != 0)

	#if (APP_USBD_STRING_ID_SERIAL != 0)
	[APP_USBD_STRING_ID_SERIAL] = APP_USBD_STRING_ID_SERIAL_ARRAY_POS,
	#endif // (APP_USBD_STRING_ID_SERIAL != 0)

	#if (APP_USBD_STRING_ID_CONFIGURATION != 0)
	[APP_USBD_STRING_ID_CONFIGURATION] = APP_USBD_STRING_ID_CONFIGURATION_ARRAY_POS,
	#endif // (APP_USBD_STRING_ID_CONFIGURATION != 0)

	#define X(mnemonic, str_idx, ...) [mnemonic] = CONCAT_2(mnemonic, _ARRAY_POS),
	APP_USBD_STRINGS_USER
	#undef X
	};

	#ifndef APP_USBD_STRINGS_MANUFACTURER_EXTERN
	#define APP_USBD_STRINGS_MANUFACTURER_EXTERN 0
	#endif

	#if APP_USBD_STRINGS_MANUFACTURER_EXTERN
	extern uint8_t APP_USBD_STRINGS_MANUFACTURER[];
	#endif

	#ifndef APP_USBD_STRINGS_PRODUCT_EXTERN
	#define APP_USBD_STRINGS_PRODUCT_EXTERN 0
	#endif

	#if APP_USBD_STRINGS_PRODUCT_EXTERN
	extern uint8_t APP_USBD_STRINGS_PRODUCT[];
	#endif

	#ifndef APP_USBD_STRING_SERIAL_EXTERN
	#define APP_USBD_STRING_SERIAL_EXTERN 0
	#endif

	#if APP_USBD_STRING_SERIAL_EXTERN
	extern uint8_t APP_USBD_STRING_SERIAL[];
	#endif

	#ifndef APP_USBD_STRING_CONFIGURATION_EXTERN
	#define APP_USBD_STRING_CONFIGURATION_EXTERN 0
	#endif

	#if APP_USBD_STRING_CONFIGURATION_EXTERN
	extern uint8_t APP_USBD_STRING_CONFIGURATION[];
	#endif

	/**
	* @brief String descriptor table.
	* */
	static uint8_t const * m_string_dsc[APP_USBD_STRING_ID_CNT][ARRAY_SIZE(m_langids)] =
	{
	[APP_USBD_STRING_ID_LANGIDS_ARRAY_POS] = {APP_USBD_STRING_RAW16_DESC(APP_USBD_STRINGS_LANGIDS)},

	#if (APP_USBD_STRING_ID_MANUFACTURER != 0)
	[APP_USBD_STRING_ID_MANUFACTURER_ARRAY_POS] = { APP_USBD_STRINGS_MANUFACTURER },
	#endif // (APP_USBD_STRING_ID_MANUFACTURER != 0)

	#if (APP_USBD_STRING_ID_PRODUCT != 0)
	[APP_USBD_STRING_ID_PRODUCT_ARRAY_POS] = { APP_USBD_STRINGS_PRODUCT },
	#endif // (APP_USBD_STRING_ID_PRODUCT != 0)

	#if (APP_USBD_STRING_ID_SERIAL != 0)
	[APP_USBD_STRING_ID_SERIAL_ARRAY_POS] = { APP_USBD_STRING_SERIAL },
	#endif // (APP_USBD_STRING_ID_SERIAL != 0)

	#if (APP_USBD_STRING_ID_CONFIGURATION != 0)
	[APP_USBD_STRING_ID_CONFIGURATION_ARRAY_POS] = { APP_USBD_STRINGS_CONFIGURATION },
	#endif // (APP_USBD_STRING_ID_CONFIGURATION != 0)

	#define X(mnemonic, str_idx, ...) [CONCAT_2(mnemonic, _ARRAY_POS)] = {__VA_ARGS__},
	APP_USBD_STRINGS_USER
	#undef X
	};

	/**
	* @brief Function for preparing UTF16 string descriptor.
	*
	* @param idx String descriptor ID.
	* @param langid Language ID.
	*
	* @return Pointer to the string descriptor.
	*/
	static uint16_t * app_usbd_prepare_string(uint8_t idx, uint16_t langid)
	{
	if (m_string_dsc[idx][langid][0] == 0x00)
	{
	return (uint16_t *) &(m_string_dsc[idx][langid][2]);
	}

	#if ((APP_USBD_CONFIG_DESC_STRING_SIZE * 2) + 2) <= NRF_DRV_USBD_EPSIZE
	uint16_t * string_buffer = app_usbd_core_setup_transfer_buff_get(NULL);
	#else
	static uint16_t string_buffer[APP_USBD_CONFIG_DESC_STRING_SIZE + 1];
	// + 1 element for string descriptor type and size
	#endif

	uint8_t size = 0;
	const uint8_t * p_pos = m_string_dsc[idx][langid];

	#if APP_USBD_CONFIG_DESC_STRING_UTF_ENABLED
	size = utf8UTF16Count((char *) p_pos, 0);
	ASSERT(size <= APP_USBD_CONFIG_DESC_STRING_SIZE);

	uint16_t * p_out = &(string_buffer[1]);
	uint32_t rune;

	while (*p_pos != 0)
	{
	p_pos = (uint8_t ) utf8DecodeRune((char ) p_pos, 0, &rune);
	p_out += utf16EncodeRune(rune, p_out);
	}
	#else
	while(*p_pos != 0)
	{
	ASSERT(size < APP_USBD_CONFIG_DESC_STRING_SIZE);
	++size;
	string_buffer[size] = *p_pos;
	++p_pos;
	}
	#endif

	// Descriptor size is length of the string times 2 bytes per character + 2 bytes for
	// descriptor type and size.
	string_buffer[0] = (0xff & (size * 2 + 2)) \| ((uint16_t)APP_USBD_DESCRIPTOR_STRING) << 8;

	return string_buffer;
	}

	uint16_t const * app_usbd_string_desc_get(uint8_t idx, uint16_t langid)
	{
	/* LANGID string. */
	if (APP_USBD_STRING_ID_LANGIDS == idx)
	{
	return app_usbd_prepare_string(APP_USBD_STRING_ID_LANGIDS_ARRAY_POS, 0);
	}

	/* Searching for the language. */
	uint8_t lang_idx = 0;
	if (ARRAY_SIZE(m_langids) > 1)
	{
	while (m_langids[lang_idx] != langid)
	{
	++lang_idx;
	if (lang_idx >= ARRAY_SIZE(m_langids))
	{
	return NULL;
	}
	}
	}

	/* Get the string index in array. */
	if (idx >= ARRAY_SIZE(m_string_translation))
	{
	return NULL;
	}

	uint8_t str_pos = m_string_translation[idx];
	if (str_pos == 0)
	{
	return NULL;
	}

	if ((ARRAY_SIZE(m_langids) > 1) && (lang_idx != 0))
	{
	if (m_string_dsc[str_pos][lang_idx] == NULL)
	{
	lang_idx = 0;
	}
	}

	if (m_string_dsc[str_pos][lang_idx] == NULL)
	{
	return NULL;
	}

	return app_usbd_prepare_string(str_pos, lang_idx);
	}

	/** @} */
	#endif // APP_USBD_ENABLED