10 minute hack to get the launchpad to give me sexy feedback

gistfile1.c

//
//  main.c
//  lpfeedback
//
//  Created by John Heaton on 3/23/13.
//  Copyright (c) 2013 John Heaton. All rights reserved.
//

#include <CoreFoundation/CoreFoundation.h>
#include <CoreMIDI/CoreMIDI.h>


#define BG_COLOR_VELOCITY 13 // dark red
#define NOTE_COLOR_VELOCITY 127 // bright amber

// ************ NOTE **************
//
// this doesn't play with with DAW's yet because it doesn't properly check
// the message type incoming from the LP
//
// therefore it's impossible to switch modes. easy fix though if you want to do it
// ********************************


static struct {
    MIDIClientRef client;
    MIDIDeviceRef launchpad;
    MIDIPortRef input_port, output_port;
    MIDIEndpointRef dest, source;
} midi_ctx;

void lp_send_msg(unsigned char msg[3]) {
    unsigned char buf[1024];
    bzero(buf, 1024);
    
    MIDIPacketList *list = (MIDIPacketList *)buf;
    MIDIPacket *p = MIDIPacketListInit(list);
    p = MIDIPacketListAdd(list, 1024, p, 0, 3, msg);
    
    printf("x\n");
    MIDISend(midi_ctx.output_port, midi_ctx.dest, list);
}

void lp_input_msg(const MIDIPacketList *pktlist, void *readProcRefCon, void *srcConnRefCon) {
    printf("msg\n");
//    @textblock
//    MIDIPacket *packet = &packetList->packet[0];
//    for (int i = 0; i < packetList->numPackets; ++i) {
//        ...
//        packet = MIDIPacketNext(packet);
//    }
    
    MIDIPacket *p = &pktlist->packet[0];
    for(int i=0;i<pktlist->numPackets;++i) {
        unsigned char msg[3];
        msg[1] = p->data[1];
        msg[2] = (p->data[0] == 0x90 && p->data[2] > 0 ? 127 : 13);
        msg[0] = p->data[0];
        lp_send_msg(msg);
        
        p = MIDIPacketNext(p);
    }
}


int is_launchpad(MIDIDeviceRef device) {
    CFStringRef name;
    
    MIDIObjectGetStringProperty(device, kMIDIPropertyName, &name);
    if(CFStringCompare(name, CFSTR("Launchpad"), kCFCompareCaseInsensitive) != 0)
        return 0;
    
    return 1;
}

int launchpad_init() {
    int c = MIDIGetNumberOfDevices();
    int ret_found = 0;
    
    for(int i=0;i<c;++i) {
        MIDIDeviceRef d = MIDIGetDevice(i);
        
        if(!is_launchpad(d))
            continue;
        else
            ret_found = 1;
        
        MIDIEntityRef e = MIDIDeviceGetEntity(d, 0);
        midi_ctx.source = MIDIEntityGetSource(e, 0);
        midi_ctx.dest = MIDIEntityGetDestination(e, 0);
        
        MIDIClientCreate(CFSTR("lpfeedback"), NULL/*change this*/, NULL, &midi_ctx.client);
        MIDIInputPortCreate(midi_ctx.client, CFSTR("lpfeedback-in"), lp_input_msg, NULL, &midi_ctx.input_port);
        MIDIOutputPortCreate(midi_ctx.client, CFSTR("lpfeedback-out"), &midi_ctx.output_port);
        
        MIDIPortConnectSource(midi_ctx.input_port, midi_ctx.source, NULL);
    }
    
    return ret_found;
}

void set_lp_grid_color(int velocity) {
    for(int i=35;i<108;++i) {
        unsigned char msg[3] = { 0x90, i, velocity };
        lp_send_msg(msg);
    }
}

int main(int argc, const char * argv[])
{
    if(!launchpad_init()) {
        fprintf(stderr, "fuck\n");
        return 1;
    }
    
    printf("got lp\n");
    set_lp_grid_color(13);
    
    CFRunLoopRun();
    
    return 0;
}