CODEWITHSUNDEEP
iphoneobjective-cexc-bad-access
coder
coder

Reputation: 10520

weird EXC_BAD_ACCESS

I have a for loop in my Objective-C code that keeps throwing a EXC_BAD_ACCESS error. Here is the code:

double (*X)[2];

for (int bufferCount=0; bufferCount < audioBufferList.mNumberBuffers; bufferCount++) {
    SInt16* samples = (SInt16 *)audioBufferList.mBuffers[bufferCount].mData;
    for (int i=0; i < 1024; i+=2){//numSamplesInBuffer / 2; i+=2) {
        X[i][0] = samples[i];
        X[i][1] = samples[i + 1];

        NSLog(@"left: %f", X[i][0]);
        NSLog(@"right: %f", X[i][1]);
        NSLog(@"i: %d", i);
    }
}

When i = 385, I get a EXC_BAD_ACCESS at the line NSLog(@"left: %f:", X[i][0]);.

Thinking it may be a memory issue with X being declared locally, I changed X to a property which caused a EXC_BAD_ACCESS at the first line of the for loop on the first time through.

Anyone know why this may be happening?

Upvotes: 0

Views: 228

Answers (2)

coder
coder

Reputation: 10520

As HotLicks pointed out, the problem was that I wasn't allocating any space for the array. The solution was to initialize the array like this: 

double (*X)[2] = malloc(2 * 1024 * sizeof(double));

Upvotes: 0

Jason Coco
Jason Coco

Reputation: 78353

double X[512][2];

for (int bufferCount=0; bufferCount < audioBufferList.mNumberBuffers; bufferCount++) {
    SInt16* samples = (SInt16 *)audioBufferList.mBuffers[bufferCount].mData;
    for (int i=0; i < 512; i++) {
        int sample_offset = i * 2;
        X[i][0] = samples[sample_offset];
        X[i][1] = samples[sample_offset + 1];

        NSLog(@"left: %f", X[i][0]);
        NSLog(@"right: %f", X[i][1]);
        NSLog(@"i: %d", i);
    }
}

Upvotes: 2

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