// memhandler.h

#ifndef MEMHANDLER_H
#define MEMHANDLER_H

int allocMemory(int handle, int numElements);
int getUpdatedMemory(int handle, unsigned char* outputBuffer,
                     int numElements, int timeout);

#endif

// memhandler.c

#include "memhandler.h"
#include "atcore.h"

struct buffer {
    unsigned char* data;
    int len;
    struct buffer* next;
};

haveInitialized = 0;
struct buffer* firstBuffer;
struct buffer* lastBuffer;

int allocMemory(int handle, int numElements) {
    struct buffer* newBuffer = (struct buffer*) malloc(sizeof(struct buffer));
    newBuffer->data = malloc(numElements * sizeof(unsigned char));
    newBuffer->len = numElements;
    newBuffer->next = 0;
    if (haveInitialized) {
        lastBuffer->next = newBuffer;
    }
    else {
        firstBuffer = newBuffer;
        lastBuffer = newBuffer;
        haveInitialized = 1;
    }
    return AT_QueueBuffer(handle, newBuffer->data, numElements);
}

int getUpdatedMemory(int handle, unsigned char* outputBuffer,
                     int numElements, int timeout) {
    char* result;
    int resultSize;
    error = AT_WaitBuffer(handle, &result, &resultSize, timeout);
    if (error) {
        return error;
    }
    curBuffer = firstBuffer;
    while (curBuffer->data != result) {
        if (!curBuffer->next) {
            return 32767; // Random bogus error code.
        }
        curBuffer = firstBuffer->next;
    }

    int i;
    // NB what if resultSize < numElements?
    for (i = 0; i < numElements; ++i) {
        outputBuffer[i] = curBuffer->data[i];
    }
    return 0;
}