kRPC fixes for Arduino Due

communication.cpp

#include <krpc/communication.h>

#include <krpc/error.h>

#if defined(KRPC_COMMUNICATION_POSIX)

#include <fcntl.h>
#include <stdint.h>
#include <unistd.h>

krpc_error_t krpc_open(krpc_connection_t * connection, const krpc_connection_config_t * arg) {
  const char * port = arg;
  int fd = open(port, O_RDWR | O_NOCTTY);
  if (fd < 0)
    KRPC_RETURN_ERROR(IO, "failed to open serial port");
  *connection = fd;
  return KRPC_OK;
}

krpc_error_t krpc_close(krpc_connection_t connection) {
  close(connection);
  return KRPC_OK;
}

krpc_error_t krpc_read(krpc_connection_t connection, uint8_t * buf, size_t count) {
  size_t total = 0;
  while (total < count) {
    int result = read(connection, buf, count);
    if (result == -1) {
      KRPC_RETURN_ERROR(IO, "read failed");
    } else if (result == 0) {
      KRPC_RETURN_ERROR(EOF, "eof received");
    } else {
      total += result;
    }
  }
  return KRPC_OK;
}

krpc_error_t krpc_write(krpc_connection_t connection, const uint8_t * buf, size_t count) {
  if (count != write(connection, buf, count))
    KRPC_RETURN_ERROR(IO, "write failed");
  return KRPC_OK;
}

#endif

#if defined(KRPC_COMMUNICATION_ARDUINO)

krpc_error_t krpc_open(krpc_connection_t * connection, const krpc_connection_config_t * arg) {
  if (arg)
    (*connection)->begin(arg->speed);
  else
    (*connection)->begin(9600);
  while (!*connection) {
  }
  return KRPC_OK;
}

krpc_error_t krpc_close(krpc_connection_t connection) {
  connection->end();
  return KRPC_OK;
}

krpc_error_t krpc_read(krpc_connection_t connection, uint8_t * buf, size_t count) {
  size_t read = 0;
  while (true) {
    read += connection->readBytes(buf+read, count-read);
    if (read == count)
      return KRPC_OK;
  }
}

krpc_error_t krpc_write(krpc_connection_t connection, const uint8_t * buf, size_t count) {
  if (count != connection->write(buf, count))
    KRPC_RETURN_ERROR(IO, "write failed");
  return KRPC_OK;
}

#endif  // KRPC_PLATFORM_ARDUINO

communication.h

#pragma once

#include <USB/USBAPI.h>
#include <krpc/error.h>

#include <stddef.h>
#include <stdint.h>

#if !defined(KRPC_COMMS_CUSTOM)
  #if defined(ARDUINO)
    #define KRPC_COMMUNICATION_ARDUINO
    #ifndef __cplusplus
    #error "Require a C++ compiler to build kRPC for Arduino"
    #endif
    #include <HardwareSerial.h>
  #elif !defined(KRPC_COMMS_CUSTOM)
    #define KRPC_COMMUNICATION_POSIX
  #endif
#endif

#ifdef __cplusplus
extern "C" {
#endif

#ifdef KRPC_COMMUNICATION_POSIX
typedef int krpc_connection_t;
typedef char krpc_connection_config_t;
#endif

#ifdef KRPC_COMMUNICATION_ARDUINO
typedef Serial_ * krpc_connection_t;

typedef struct {
  uint32_t speed;
  uint8_t config;
} krpc_connection_config_t;
#endif

/* Open a connection */
krpc_error_t krpc_open(krpc_connection_t * connection, const krpc_connection_config_t * config);
/* Close a connection */
krpc_error_t krpc_close(krpc_connection_t connection);
/* Read count bytes of data from the connection into buf */
krpc_error_t krpc_read(krpc_connection_t connection, uint8_t * buf, size_t count);
/* Write count bytes of data from into buf to the connection */
krpc_error_t krpc_write(krpc_connection_t connection, const uint8_t * buf, size_t count);

#ifdef __cplusplus
}  // extern "C"
#endif

example.ino

#include <krpc.h>
#include <krpc/services/krpc.h>
#include <krpc/services/space_center.h>

Serial_ * conn;  // <- weirdly the type for SerialUSB is "Serial_"

void setup() {
  conn = &SerialUSB;
  // Open the serial port connection
  krpc_open(&conn, NULL);
  // Set up communication with the server
  krpc_connect(conn, "Arduino Example");

  ...
}

void loop() {
  ...
}