/*
 * This is an encapsulation of a National Instruments DIO port.
 *
 * It presents a simple device abstraction.
 *
 * The device can be read and returns a 32-bit unsigned value.
 */
#ifndef _HWARE_H_
#define _HWARE_H_

#ifdef __cplusplus
#else
#include <stdbool.h>
#endif

struct device_private_t;
typedef struct device_private_t* pHWARE;
typedef unsigned int HWARE_VALUE;

/**
 * Create a device
 *
 * \param card_name the name of the device (e.g. "dev1/port0")
 * \param ptr address of pointer to opaque private data structure
 *
 * \return
 *   0 OK
 *  !0 Error
 */
int hware_ctor(const char* card_name, pHWARE* ptr);

/**
 * Read the value of the device
 *
 * \param hware pointer to opaque private data structure
 * \param value address of value to receive the output
 *
 * \return
 *   0 OK
 *  !0 Error
 */
int hware_read(pHWARE hware, HWARE_VALUE* value);

/**
 * Write the value of the device
 *
 * \param hware pointer to opaque private data structure
 * \param value to be written to the device
 *
 * \return
 *   0 OK
 *  !0 Error
 */
int hware_write(pHWARE hware, HWARE_VALUE value);

/**
 * Destroy the device
 *
 * \param ptr address of pointer to opaque private data structure
 *
 * \return
 *   0 OK
 *  !0 Error
 */
int hware_dtor(pHWARE* hware);

/**
 * Tests returned error value to see if it represents failure
 *
 * \param error a value returned from another hware function
 *
 * \return
 *   true the error was a failure
 *   false the error was not a failure (warning)
 */
bool hware_failed(int error);

/**
 * Retrieves a textual representation of the most recent error
 *
 * \param buff a pointer to the buffer to receive the text
 * \param len the length of the provided buffer
 */
void hware_errmsg(char* buff, int len);

#endif