/***************************************************************************
 * Copyright (c) 2024 Microsoft Corporation
 * Copyright (c) 2025-2026 STMicroelectronics.
 *
 * This program and the accompanying materials are made available under the
 * terms of the MIT License which is available at
 * https://opensource.org/licenses/MIT.
 *
 * SPDX-License-Identifier: MIT
 **************************************************************************/


/**************************************************************************/
/**************************************************************************/
/**                                                                       */
/** USBX Component                                                        */
/**                                                                       */
/**   STM32 Controller Driver                                             */
/**                                                                       */
/**************************************************************************/
/**************************************************************************/


/* Include necessary system files.  */

#define UX_SOURCE_CODE
#define UX_HCD_STM32_SOURCE_CODE

#include "ux_api.h"
#include "ux_hcd_stm32.h"
#include "ux_host_stack.h"


/**************************************************************************/
/*                                                                        */
/*  FUNCTION                                               RELEASE        */
/*                                                                        */
/*    _ux_hcd_stm32_least_traffic_list_get                PORTABLE C      */
/*                                                           6.4.1        */
/*  AUTHOR                                                                */
/*                                                                        */
/*    Chaoqiong Xiao, Microsoft Corporation                               */
/*                                                                        */
/*  DESCRIPTION                                                           */
/*                                                                        */
/*     This function return a pointer to the first ED in the periodic     */
/*     tree that has the least traffic registered.                        */
/*                                                                        */
/*  INPUT                                                                 */
/*                                                                        */
/*    hcd_stm32                               Pointer to STM32 controller */
/*                                                                        */
/*  OUTPUT                                                                */
/*                                                                        */
/*    UX_HCD_STM32_ED *                       Pointer to STM32 ED         */
/*                                                                        */
/*  CALLS                                                                 */
/*                                                                        */
/*    None                                                                */
/*                                                                        */
/*  CALLED BY                                                             */
/*                                                                        */
/*    STM32 Controller Driver                                             */
/*                                                                        */
/*  RELEASE HISTORY                                                       */
/*                                                                        */
/*    DATE              NAME                      DESCRIPTION             */
/*                                                                        */
/*  05-19-2020     Chaoqiong Xiao           Initial Version 6.0           */
/*                                                                        */
/**************************************************************************/
UINT _ux_hcd_stm32_least_traffic_list_get(UX_HCD_STM32 *hcd_stm32)
{
  UX_HCD_STM32_ED     *ed;
  UINT                list_index;
  ULONG               min_bandwidth_used;
  ULONG               bandwidth_used;
  UINT                min_bandwidth_slot;

  /* Set the min bandwidth used to a arbitrary maximum value.  */
  min_bandwidth_used = 0xffffffff;

  /* The first ED is the list candidate for now.  */
  min_bandwidth_slot = 0;

  /* All list will be scanned.  */
  for (list_index = 0; list_index < 32; list_index++)
  {
    /* Reset the bandwidth for this list.  */
    bandwidth_used = 0;

    /* Get the ED of the beginning of the list we parse now.  */
    ed = hcd_stm32 -> ux_hcd_stm32_periodic_ed_head;

    /* Parse the eds in the list.  */
    while (ed != UX_NULL)
    {
      if ((list_index & ed -> ux_stm32_ed_interval_mask) == ed -> ux_stm32_ed_interval_position)
      {
        /* Add to the bandwidth used the max packet size pointed by this ED.  */
        bandwidth_used += (ULONG) ed -> ux_stm32_ed_endpoint -> ux_endpoint_descriptor.wMaxPacketSize;
      }

      /* Move to next ED.  */
      ed = ed -> ux_stm32_ed_next_ed;
    }

    /* We have processed a list, check the bandwidth used by this list.
       If this bandwidth is the minimum, we memorize the ED.  */
    if (bandwidth_used < min_bandwidth_used)
    {
      /* We have found a better list with a lower used bandwidth, memorize the bandwidth
         for this list.  */
      min_bandwidth_used = bandwidth_used;

      /* Memorize the begin ED for this list.  */
      min_bandwidth_slot = list_index;
    }
  }

  /* Return the ED list with the lowest bandwidth.  */
  return(min_bandwidth_slot);
}