FILTER.C

/************************************************************************** 
 * 
 *  THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY 
 *  KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE 
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR 
 *  PURPOSE. 
 * 
 *  Copyright 1993 - 1998 Microsoft Corporation.  All Rights Reserved. 
 *  
 **************************************************************************/ 
 
/* 
 * filter.c - Routines to filter MIDI events. 
 */ 
 
#include <windows.h> 
#include "midimon.h" 
#include "display.h" 
#include "filter.h" 
 
/* CheckEventFilter - Checks the given EVENT against the given FILTER. 
 *       
 * Params:  lpEvent - Points to an EVENT. 
 *          lpFilter - Points to a FILTER structure. 
 * 
 * Return:  Returns 1 if the event is filtered, 0 if it is not filtered. 
 */ 
BOOL CheckEventFilter(LPEVENT lpEvent, LPFILTER lpFilter) 
{ 
    BYTE bStatus, bStatusRaw, bChannel, bData1, bData2; 
 
    /* Get the essential info from the EVENT. 
     */ 
    bStatusRaw = LOBYTE(LOWORD(lpEvent->data)); 
    bStatus = bStatusRaw & (BYTE) 0xf0; 
    bChannel = LOBYTE(LOWORD(lpEvent->data)) & (BYTE) 0x0f; 
    bData1 = HIBYTE(LOWORD(lpEvent->data)); 
    bData2 = LOBYTE(HIWORD(lpEvent->data)); 
 
    /* Do channel filtering for all but system events. 
     */ 
    if(bStatus != SYSTEMMESSAGE){ 
        if(lpFilter->channel[bChannel]) 
            return 1; 
    } 
 
    /* Do event-type filtering. 
     */ 
    switch(bStatus){ 
        case NOTEOFF: 
            if(lpFilter->event.noteOff) 
                return 1; 
            break; 
 
        case NOTEON: 
            /* A note on with a velocity of 0 is a note off. 
             */ 
            if(bData2 == 0){ 
                if(lpFilter->event.noteOff) 
                    return 1; 
                break; 
            } 
             
            if(lpFilter->event.noteOn) 
                return 1; 
            break; 
 
        case KEYAFTERTOUCH: 
            if(lpFilter->event.keyAftertouch) 
                return 1; 
            break; 
 
        case CONTROLCHANGE: 
            if(lpFilter->event.controller) 
                return 1; 
             
            /* Channel mode messages can be filtered. 
             */ 
            if((bData1 >= 121) && lpFilter->event.channelMode) 
                return 1; 
            break; 
 
        case PROGRAMCHANGE: 
            if(lpFilter->event.progChange) 
                return 1; 
            break; 
 
        case CHANAFTERTOUCH: 
            if(lpFilter->event.chanAftertouch) 
                return 1; 
            break; 
 
        case PITCHBEND: 
            if(lpFilter->event.pitchBend) 
                return 1; 
            break; 
 
        case SYSTEMMESSAGE: 
            /* System common messages. 
             */ 
            if((bStatusRaw < 0xf8) && (lpFilter->event.sysCommon)) 
                return 1; 
 
            /* Active sensing messages. 
             */ 
            if((bStatusRaw == 0xfe) && (lpFilter->event.activeSense)) 
                return 1; 
 
            /* System real time messages. 
             */ 
            if((bStatusRaw >= 0xf8) && lpFilter->event.sysRealTime) 
                return 1; 
            break; 
 
        default: 
            break; 
    } 
 
    return 0; 
}