someone explain this code? (directx)

Code:

#define AXIS_THRESHOLD  20

void HandleAction(UINT nAction, DWORD dwData)
{
    int nAxisPos = (int)dwData;

    switch (nAction)
    {
    case ACTIONS_LEFTRIGHT:
        if (nAxisPos < -AXIS_THRESHOLD)
        {
            g_bLeft = true;
            g_bRight = false;
        }
        else if (nAxisPos > AXIS_THRESHOLD)
        {
            g_bRight = true;
            g_bLeft = false;
        }
        else
        {
            g_bLeft = g_bRight = false;
        }
        break;
    
    case ACTIONS_LEFT:
        g_bLeft = (dwData != 0);
        break;

    case ACTIONS_RIGHT:
        g_bRight = (dwData != 0);
        break;

    case ACTIONS_QUIT:
        g_bQuit = true;
        break;
    
    default:
        break;
    }
}

could someone explain how "g_bRight = (dwData !=0)" works, and the part about the axis threshold? (from sunlight's tutorials)
oh and if this helps:

Code:

// Check each device for actions
void CheckInput()
{
    DIDEVICEOBJECTDATA  pdidod[INPUT_DATA_LIMIT];
    DWORD               dwObjCount;

    if (g_pDeviceArray == NULL)
        return;

    for (int iDevice = 0; iDevice < g_nDevices; iDevice++)
    {
        // Poll the device for data. 
        g_pDeviceArray[iDevice]->Poll(); 
 
        // Retrieve the data.
        dwObjCount = INPUT_DATA_LIMIT;
        g_pDeviceArray[iDevice]->GetDeviceData(sizeof(DIDEVICEOBJECTDATA),
                                               pdidod,
                                               &dwObjCount, 0);
        for (DWORD i = 0; i < dwObjCount; i++)
            // Handle the actions regardless of what device returned them.
            HandleAction(pdidod[i].uAppData, pdidod[i].dwData);
    }
}

>g_bRight = (dwData !=0)"
g_bRight is assigned the boolean value of dwData != 0, so g_bRight will have either 1 or 0. The expression can be broken down like this, assuming dwData is 0:

g_bRight = (dwData !=0)
g_bRight = (0 !=0) // False
g_bRight = 0

Bebop