/*---------------------------------------------------------------------------*
  Project:  TwlSDK - MB - demos - mbm
  File:     mb_measure_channel.c

  Copyright 2006-2008 Nintendo. All rights reserved.

  These coded instructions, statements, and computer programs contain
  proprietary information of Nintendo of America Inc. and/or Nintendo
  Company Ltd., and are protected by Federal copyright law. They may
  not be disclosed to third parties or copied or duplicated in any form,
  in whole or in part, without the prior written consent of Nintendo.

  $Date:: 2008-09-18#$
  $Rev: 8573 $
  $Author: okubata_ryoma $
 *---------------------------------------------------------------------------*/

#include <nitro/wm.h>

#include "mb_measure_channel.h"

#define MBM_DEBUG

#ifdef MBM_DEBUG
#define PRINTF OS_TPrintf
#else
#define PRINTF(...) ((void)0)
#endif

#define MBM_MEASURE_DMA_NO                 2

// Random number macro
#define RAND()  ( sRand = sRand + 69069UL + 12345 )
#define RAND_INIT(x) ( sRand = (u32)(x) )

enum
{
    MBM_STATE_INIT,                    // Initial state
    MBM_STATE_MEASURING,               // Start state
    MBM_STATE_END_MEASURE,             // End measuring
    MBM_STATE_END,                     // State with wireless communications off
    MBM_STATE_ERR                      // Error
};


enum
{
    ERRCODE_SUCCESS = 0,               // Success
    ERRCODE_NOMORE_CHANNEL,            // No more channels can be found
    ERRCODE_API_ERR                    // WM API execution error
};

//===========================================================================
// Variable Declarations
//===========================================================================

static u32 sRand;

static MBMCallbackFunc sUserCallbackFunc = NULL;
static int mbm_measure_state = MBM_STATE_END;
// For communication channel storage
static s16 sChannel;
static u16 sChannelBitmap;
static u16 sChannelBusyRatio;

static BOOL sUseInIdle = FALSE;


//===========================================================================
// Function Prototype Declarations
//===========================================================================

static int wmi_measure_channel(WMCallbackFunc callback, u16 channel);
static void wm_callback(void *arg);
static void start_measure_channel(void);
static u16 state_in_measure_channel(u16 channel);
static void state_out_measure_channel(void *arg);
static void state_in_wm_end(void);
static void user_callback(s16 num);
static void change_mbm_state(u16 state);
static void callback_ready(s16 result);
static s16 select_channel(u16 bitmap);

//===========================================================================
// Function Definitions
//===========================================================================

/* ----------------------------------------------------------------------
  Checks the signal use rate
  ---------------------------------------------------------------------- */
static inline int wmi_measure_channel(WMCallbackFunc callback, u16 channel)
{
#define MBM_MEASURE_TIME         30    // The time interval in ms for picking up the signal to carry out communication for one frame
#define MBM_MEASURE_CS_OR_ED     3     // The logical OR of the carrier sense and the ED value
#define MBM_MEASURE_ED_THRESHOLD 17    // The recommended ED threshold value that has been empirically shown to be effective

    /*
     * A value considered to be empirically valid is used as a parameter for getting the wireless activity ratio
     * 
     */
    return WM_MeasureChannel(callback, // Callback settings
                             MBM_MEASURE_CS_OR_ED,      // CS or ED
                             MBM_MEASURE_ED_THRESHOLD,  // Invalid when only carrier sense
                             channel,  // One of the channels obtained with WM_GetAllowedChannel
                             MBM_MEASURE_TIME); //The search time per channel (in ms)
}



/*---------------------------------------------------------------------------*
  Name:         MBM_MeasureChannel

  Description:  Searches for the channel with the lowest usage rate.
                Call in the wireless OFF state.
                Returns a callback after internally measuring the radio and setting it to a wireless OFF state.

  Arguments:    wm_buffer: WM work memory
                callback: Designates the user callback to call when the search has finished

  Returns:      None.
 *---------------------------------------------------------------------------*/
void MBM_MeasureChannel(u8 *wm_buffer, MBMCallbackFunc callback)
{
    sUseInIdle = FALSE;
    sUserCallbackFunc = callback;

    // Starts the initialization sequence
    if (mbm_measure_state != MBM_STATE_END)
    {
        user_callback(MBM_MEASURE_ERROR_ILLEGAL_STATE);
        return;
    }

    if (WM_Initialize(wm_buffer, wm_callback, MBM_MEASURE_DMA_NO) != WM_ERRCODE_OPERATING)
    {
        user_callback(MBM_MEASURE_ERROR_INIT_API);
        return;
    }
}

/*---------------------------------------------------------------------------*
  Name:         MBM_MeasureChannelInIdle

  Description:  Searches for the channel with the lowest usage rate.
                Call in the idle state.
                Returns a callback after internally measuring and setting the radio to the IDLE state.

  Arguments:    callback: Designates the user callback to call when the search has finished

  Returns:      None.
 *---------------------------------------------------------------------------*/
void MBM_MeasureChannelInIdle(MBMCallbackFunc callback)
{
    sUseInIdle = TRUE;
    sUserCallbackFunc = callback;

    // Starts the initialization sequence
    if (mbm_measure_state != MBM_STATE_END)
    {
        user_callback(MBM_MEASURE_ERROR_ILLEGAL_STATE);
        return;
    }

    start_measure_channel();
}

/* ----------------------------------------------------------------------
  WM callback
  ---------------------------------------------------------------------- */
static void wm_callback(void *arg)
{
    WMCallback *cb = (WMCallback *)arg;

    switch (cb->apiid)
    {
    case WM_APIID_INITIALIZE:
        /* WM_Initialize callback */
        {
            WMCallback *cb = (WMCallback *)arg;
            if (cb->errcode != WM_ERRCODE_SUCCESS)
            {
                user_callback(MBM_MEASURE_ERROR_INIT_CALLBACK);
                return;
            }
        }
        change_mbm_state(MBM_STATE_INIT);
        start_measure_channel();
        break;

    case WM_APIID_MEASURE_CHANNEL:
        /* WM_MeasureChannel callback */
        state_out_measure_channel(arg);
        break;

    case WM_APIID_END:
        change_mbm_state(MBM_STATE_END);
        user_callback(sChannel);
        break;

    default:
        OS_TPanic("Get illegal callback");

        break;
    }
}

/* ----------------------------------------------------------------------
  Begin searching for the radio usage rate
  ---------------------------------------------------------------------- */
static void start_measure_channel(void)
{
#define MAX_RATIO 100                  // The channel use rate is between 0 and 100
    u16     result;
    u8      macAddr[6];

    OS_GetMacAddress(macAddr);
    RAND_INIT(OS_GetVBlankCount() + *(u16 *)&macAddr[0] + *(u16 *)&macAddr[2] + *(u16 *)&macAddr[4]);   // Random number initialization
    RAND();

    sChannel = 0;
    sChannelBitmap = 0;
    sChannelBusyRatio = MAX_RATIO + 1;

    result = state_in_measure_channel(1);       // Check in order from channel 1

    if (result == ERRCODE_NOMORE_CHANNEL)
    {
        // There are not any channels available
        callback_ready(MBM_MEASURE_ERROR_NO_ALLOWED_CHANNEL);
        return;
    }

    if (result == ERRCODE_API_ERR)
    {
        // Error complete
        callback_ready(MBM_MEASURE_ERROR_MEASURECHANNEL_API);
        return;
    }

    // Begin measuring the radio usage rate
    change_mbm_state(MBM_STATE_MEASURING);
}


/*---------------------------------------------------------------------------*
  Name:         state_in_measure_channel

  Arguments:    channel: The channel number to start the search at

  Returns:      ERRCODE_SUCCESS        - Searching
                ERRCODE_NOMORE_CHANNEL - There are no more channels to search
                ERRCODE_API_ERR        - WM_MeasureChannel API callback error
 *---------------------------------------------------------------------------*/
static u16 state_in_measure_channel(u16 channel)
{
    u16     allowedCannel;

    allowedCannel = WM_GetAllowedChannel();

    while (((1 << (channel - 1)) & allowedCannel) == 0)
    {
        channel++;
        if (channel > 16)
        {
            /* When finished searching all allowed channels */
            return ERRCODE_NOMORE_CHANNEL;
        }
    }

    if (wmi_measure_channel(wm_callback, channel) != WM_ERRCODE_OPERATING)
    {
        return ERRCODE_API_ERR;
    }
    return ERRCODE_SUCCESS;
}


static void state_out_measure_channel(void *arg)
{
    u16     result;
    u16     channel;
    WMMeasureChannelCallback *cb = (WMMeasureChannelCallback *)arg;

    if (cb->errcode != WM_ERRCODE_SUCCESS)
    {
        callback_ready(MBM_MEASURE_ERROR_MEASURECHANNEL_CALLBACK);
        return;
    }

    channel = cb->channel;
    PRINTF("CH%d = %d\n", cb->channel, cb->ccaBusyRatio);

    if (cb->ccaBusyRatio < sChannelBusyRatio)
    {
        sChannelBusyRatio = cb->ccaBusyRatio;
        sChannelBitmap = (u16)(1 << (channel - 1));
    }
    else if (cb->ccaBusyRatio == sChannelBusyRatio)
    {
        sChannelBitmap |= (u16)(1 << (channel - 1));
    }

    result = state_in_measure_channel(++channel);

    if (result == ERRCODE_NOMORE_CHANNEL)
    {
        // The channel search ends
        callback_ready(select_channel(sChannelBitmap));
        return;
    }

    if (result == ERRCODE_API_ERR)
    {
        // Error complete
        callback_ready(MBM_MEASURE_ERROR_MEASURECHANNEL_API);
        return;
    }

    // Do nothing if ERRCODE_SUCCESS

}


/* ----------------------------------------------------------------------
  Turn off wireless before the callback
  ---------------------------------------------------------------------- */
static void callback_ready(s16 result)
{
    sChannel = result;
    if (sUseInIdle)
    {
        change_mbm_state(MBM_STATE_END);
        user_callback(result);
    }
    else
    {
        state_in_wm_end();
        change_mbm_state(MBM_STATE_END_MEASURE);
    }
}

/* ----------------------------------------------------------------------
  End WM
  ---------------------------------------------------------------------- */
static void state_in_wm_end(void)
{
    if (WM_End(wm_callback) != WM_ERRCODE_OPERATING)
    {
        OS_TPanic("fail WM_End");
    }
}


/* ----------------------------------------------------------------------
  Change the MBM internal state
  ---------------------------------------------------------------------- */
static void change_mbm_state(u16 state)
{
#ifdef MBM_DEBUG
    static const char *STATE_STR[] = {
        "INIT",
        "MEASURING",                   // Start state
        "END_MEASURE",                 // End measuring
        "END",                         // State with wireless communications off
        "ERR"                          // Error
    };
#endif

    PRINTF("%s -> ", STATE_STR[mbm_measure_state]);
    mbm_measure_state = state;
    PRINTF("%s\n", STATE_STR[mbm_measure_state]);
}

/* ----------------------------------------------------------------------
  Determine the channel
  ---------------------------------------------------------------------- */
static s16 select_channel(u16 bitmap)
{
    s16     i;
    s16     channel = 0;
    u16     num = 0;
    u16     select;

    for (i = 0; i < 16; i++)
    {
        if (bitmap & (1 << i))
        {
            channel = (s16)(i + 1);
            num++;
        }
    }

    if (num <= 1)
    {
        return channel;
    }

    // If there are multiple channels of the same signal usage rate
    select = (u16)(((RAND() & 0xFF) * num) / 0x100);

    channel = 1;

    for (i = 0; i < 16; i++)
    {
        if (bitmap & 1)
        {
            if (select == 0)
            {
                return (s16)(i + 1);
            }
            select--;
        }
        bitmap >>= 1;
    }

    return 0;
}

/* ----------------------------------------------------------------------
  Call the user callback
  ---------------------------------------------------------------------- */
static void user_callback(s16 type)
{
    MBMCallback arg;

    if (!sUserCallbackFunc)
    {
        return;
    }

    if (type > 0)
    {
        arg.errcode = MBM_MEASURE_SUCCESS;
        arg.channel = (u16)type;
    }
    else
    {
        arg.errcode = type;
        arg.channel = 0;
    }
    sUserCallbackFunc(&arg);
}