.. _BUILD:

Building GHDL from Sources
##########################

.. rubric :: Download

GHDL can be downloaded as a `zip-file <https://github.com/ghdl/ghdl/archive/master.zip>`_/`tar-file <https://github.com/ghdl/ghdl/archive/master.tar.gz>`_
(latest 'master' branch) or cloned with ``git clone`` from GitHub. GitHub
offers HTTPS and SSH as transfer protocols. See the :ref:`RELEASE:Sources`
page for further details.

.. IMPORTANT::
   Since GHDL is written in `Ada`, independently of the code generator you use,
   the a compiler is required. Most GNU/Linux package managers provide a package
   named ``gcc-ada`` or ``gcc-gnat``. Alternatively, `GNU Ada compiler`, `GNAT GPL`,
   can be downloaded anonymously from `libre.adacore.com <http://libre.adacore.com/tools/gnat-gpl-edition/>`_ (2014, or later; for x86, 32 or 64 bits).
   Then, untar and run the doinstall script.

.. ATTENTION::
   Since ``v0.37``, GHDL's synthesis features require GCC >=8.1, due to some new GNAT features which
   are not available in previous releases. Users with older versions (who don't need synthesis)
   can configure GHDL with option ``--disable-synth``.

.. rubric :: Available back-ends

GHDL currently supports three different back-ends (code generators):

* mcode - built-in x86 (or x86_64) code generator
* GCC - Gnu Compiler Collection (`gcc.gnu.org <http://gcc.gnu.org/>`_)
* LLVM - Low-Level Virtual Machine (`llvm.org <http://llvm.org/>`_)

Here is a short comparison, so that you can choose the one you want to use:

+----------------------------+----------------------------------------------------------------------------+---------------------------------------------------------+
| Back-end                   | Pros                                                                       | Cons                                                    |
+============================+============================================================================+=========================================================+
| :ref:`mcode <BUILD:mcode>` | * Very easy to build                                                       | * Simulation is slower                                  |
|                            | * Very quick analysis                                                      | * x86_64/i386 only                                      |
|                            | * Can handle very large designs                                            |                                                         |
+----------------------------+----------------------------------------------------------------------------+---------------------------------------------------------+
| :ref:`LLVM <BUILD:llvm>`   | * Generated code is faster                                                 | * Build is more complex than mcode                      |
|                            | * Generated code can be debugged (with ``-g``)                             |                                                         |
|                            | * Easier to build than GCC                                                 |                                                         |
|                            | * Ported to many platforms (x86, x86_64, armv7/aarch64)                    |                                                         |
+----------------------------+----------------------------------------------------------------------------+---------------------------------------------------------+
| :ref:`GCC <BUILD:gcc>`     | * Generated code is faster (particularly with ``-O`` or ``-O2``)           | * Build is even more complex                            |
|                            | * Generated code can be debugged (with ``-g``)                             | * Analysis can take time (particularly for large units) |
|                            | * Ported to many platforms (x86, x86_64, PowerPC, SPARC)                   | * Code coverage collection (``gcov``) is unique to GCC  |
+----------------------------+---------
/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                 2011,2012,2013 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file    hal_queues.c
 * @brief   I/O Queues code.
 *
 * @addtogroup io_queues
 * @details Queues are mostly used in serial-like device drivers.
 *          Serial device drivers are usually designed to have a lower side
 *          (lower driver, it is usually an interrupt service routine) and an
 *          upper side (upper driver, accessed by the application threads).<br>
 *          There are several kind of queues:<br>
 *          - <b>Input queue</b>, unidirectional queue where the writer is the
 *            lower side and the reader is the upper side.
 *          - <b>Output queue</b>, unidirectional queue where the writer is the
 *            upper side and the reader is the lower side.
 *          - <b>Full duplex queue</b>, bidirectional queue. Full duplex queues
 *            are implemented by pairing an input queue and an output queue
 *            together.
 *          .
 * @{
 */

#include "hal.h"

#if !defined(_CHIBIOS_RT_) || !CH_CFG_USE_QUEUES || defined(__DOXYGEN__)

/**
 * @brief   Initializes an input queue.
 * @details A Semaphore is internally initialized and works as a counter of
 *          the bytes contained in the queue.
 * @note    The callback is invoked from within the S-Locked system state,
 *          see @ref system_states.
 *
 * @param[out] iqp      pointer to an @p input_queue_t structure
 * @param[in] bp        pointer to a memory area allocated as queue buffer
 * @param[in] size      size of the queue buffer
 * @param[in] infy      pointer to a callback function that is invoked when
 *                      data is read from the queue. The value can be @p NULL.
 * @param[in] link      application defined pointer
 *
 * @init
 */
void iqObjectInit(input_queue_t *iqp, uint8_t *bp, size_t size,
                  qnotify_t infy, void *link) {

  osalThreadQueueObjectInit(&iqp->q_waiting);
  iqp->q_counter = 0;
  iqp->q_buffer  = iqp->q_rdptr = iqp->q_wrptr = bp;
  iqp->q_top     = bp + size;
  iqp->q_notify  = infy;
  iqp->q_link    = link;
}

/**
 * @brief   Resets an input queue.
 * @details All the data in the input queue is erased and lost, any waiting
 *          thread is resumed with status @p Q_RESET.
 * @note    A reset operation can be used by a low level driver in order to
 *          obtain immediate attention from the high level layers.
 *
 * @param[in] iqp       pointer to an @p input_queue_t structure
 *
 * @iclass
 */
void iqResetI(input_queue_t *iqp) {

  osalDbgCheckClassI();

  iqp->q_rdptr = iqp->q_wrptr = iqp->q_buffer;
  iqp->q_counter = 0;
  osalThreadDequeueAllI(&iqp->q_waiting, Q_RESET);
}

/**
 * @brief   Input queue write.
 * @details A byte value is written into the low end of an input queue.
 *
 * @param[in] iqp       pointer to an @p input_queue_t structure
 * @param[in] b         the byte value to be written in the queue
 * @return              The operation status.
 * @retval Q_OK         if the operation has been completed with success.
 * @retval Q_FULL       if the queue is full and the operation cannot be
 *                      completed.
 *
 * @iclass
 */
msg_t iqPutI(input_queue_t *iqp, uint8_t b) {

  osalDbgCheckClassI();

  if (iqIsFullI(iqp))
    return Q_FULL;

  iqp->q_counter++;
  *iqp->q_wrptr++ = b;
  if (iqp->q_wrptr >= iqp->q_top)
    iqp->q_wrptr = iqp->q_buffer;

  osalThreadDequeueNextI(&iqp->q_waiting, Q_OK);

  return Q_OK;
}

/**
 * @brief   Input queue read with timeout.
 * @details This function reads a byte value from an input queue. If the queue
 *          is empty then the calling thread is suspended until a byte arrives
 *          in the queue or a timeout occurs.
 * @note    The callback is invoked before reading the character from the
 *          buffer or before entering the state @p THD_STATE_WTQUEUE.
 *
 * @param[in] iqp       pointer to an @p input_queue_t structure
 * @param[in] time      the number of ticks before the operation timeouts,
 *                      the following special values are allowed:
 *                      - @a TIME_IMMEDIATE immediate timeout.
 *                      - @a TIME_INFINITE no timeout.
 *                      .
 * @return              A byte value from the queue.
 * @retval Q_TIMEOUT    if the specified time expired.
 * @retval Q_RESET      if the queue has been reset.
 *
 * @api
 */
msg_t iqGetTimeout(input_queue_t *iqp, systime_t time) {
  uint8_t b;

  osalSysLock();
  if (iqp->q_notify)
    iqp->q_notify(iqp);

  while (iqIsEmptyI(iqp)) {
    msg_t msg;
    if ((msg = osalThreadEnqueueTimeoutS(&iqp->q_waiting, time)) < Q_OK) {
      osalSysUnlock();
      return msg;
    }
  }

  iqp->q_counter--;
  b = *iqp->q_rdptr++;
  if (iqp->q_rdptr >= iqp->q_top)
    iqp->q_rdptr = iqp->q_buffer;

  osalSysUnlock();
  return b;
}

/**
 * @brief   Input queue read with timeout.
 * @details The function reads data from an input queue into a buffer. The
 *          operation completes when the specified amount of data has been
 *          transferred or after the specified timeout or if the queue has
 *          been reset.
 * @note    The function is not atomic, if you need atomicity it is suggested
 *          to use a semaphore or a mutex for mutual exclusion.
 * @note    The callback is invoked before reading each character from the
 *          buffer or before entering the state @p THD_STATE_WTQUEUE.
 *
 * @param[in] iqp       pointer to an @p input_queue_t structure
 * @param[out] bp       pointer to the data buffer
 * @param[in] n         the maximum amount of data to be transferred, the
 *                      value 0 is reserved
 * @param[in] time      the number of ticks before the operation timeouts,
 *                      the following special values are allowed:
 *                      - @a TIME_IMMEDIATE immediate timeout.
 *                      - @a TIME_INFINITE no timeout.
 *                      .
 * @return              The number of bytes effectively transferred.
 *
 * @api
 */
size_t iqReadTimeout(input_queue_t *iqp, uint8_t *bp,
                     size_t n, systime_t time) {
  qnotify_t nfy = iqp->q_notify;
  size_t r = 0;

  osalDbgCheck(n > 0);

  osalSysLock();
  while (TRUE) {
    if (nfy)
      nfy(iqp);

    while (iqIsEmptyI(iqp)) {
      if (osalThreadEnqueueTimeoutS(&iqp->q_waiting, time) != Q_OK) {
        osalSysUnlock();
        return r;
      }
    }

    iqp->q_counter--;
    *bp++ = *iqp->q_rdptr++;
    if (iqp->q_rdptr >= iqp->q_top)
      iqp->q_rdptr = iqp->q_buffer;

    osalSysUnlock(); /* Gives a preemption chance in a controlled point.*/
    r++;
    if (--n == 0)
      return r;

    osalSysLock();
  }
}

/**
 * @brief   Initializes an output queue.
 * @details A Semaphore is internally initialized and works as a counter of
 *          the free bytes in the queue.
 * @note    The callback is invoked from within the S-Locked system state,
 *          see @ref system_states.
 *
 * @param[out] oqp      pointer to an @p output_queue_t structure
 * @param[in] bp        pointer to a memory area allocated as queue buffer
 * @param[in] size      size of the queue buffer
 * @param[in] onfy      pointer to a callback function that is invoked when
 *                      data is written to the queue. The value can be @p NULL.
 * @param[in] link      application defined pointer
 *
 * @init
 */
void oqObjectInit(output_queue_t *oqp, uint8_t *bp, size_t size,
                  qnotify_t onfy, void *link) {

  osalThreadQueueObjectInit(&oqp->q_waiting);
  oqp->q_counter = size;
  oqp->q_buffer  = oqp->q_rdptr = oqp->q_wrptr = bp;
  oqp->q_top     = bp + size;
  oqp->q_notify  = onfy;
  oqp->q_link    = link;
}

/**
 * @brief   Resets an output queue.
 * @details All the data in the output queue is erased and lost, any waiting
 *          thread is resumed with status @p Q_RESET.
 * @note    A reset operation can be used by a low level driver in order to
 *          obtain immediate attention from the high level layers.
 *
 * @param[in] oqp       pointer to an @p output_queue_t structure
 *
 * @iclass
 */
void oqResetI(output_queue_t *oqp) {

  osalDbgCheckClassI();

  oqp->q_rdptr = oqp->q_wrptr = oqp->q_buffer;
  oqp->q_counter = qSizeI(oqp);
  osalThreadDequeueAllI(&oqp->q_waiting, Q_RESET);
}

/**
 * @brief   Output queue write with timeout.
 * @details This function writes a byte value to an output queue. If the queue
 *          is full then the calling thread is suspended until there is space
 *          in the queue or a timeout occurs.
 * @note    The callback is invoked after writing the character into the
 *          buffer.
 *
 * @param[in] oqp       pointer to an @p output_queue_t structure
 * @param[in] b         the byte value to be written in the queue
 * @param[in] time      the number of ticks before the operation timeouts,
 *                      the following special values are allowed:
 *                      - @a TIME_IMMEDIATE immediate timeout.
 *                      - @a TIME_INFINITE no timeout.
 *                      .
 * @return              The operation status.
 * @retval Q_OK         if the operation succeeded.
 * @retval Q_TIMEOUT    if the specified time expired.
 * @retval Q_RESET      if the queue has been reset.
 *
 * @api
 */
msg_t oqPutTimeout(output_queue_t *oqp, uint8_t b, systime_t time) {

  osalSysLock();
  while (oqIsFullI(oqp)) {
    msg_t msg;

    if ((msg = osalThreadEnqueueTimeoutS(&oqp->q_waiting, time)) < Q_OK) {
      osalSysUnlock();
      return msg;
    }
  }

  oqp->q_counter--;
  *oqp->q_wrptr++ = b;
  if (oqp->q_wrptr >= oqp->q_top)
    oqp->q_wrptr = oqp->q_buffer;

  if (oqp->q_notify)
    oqp->q_notify(oqp);

  osalSysUnlock();
  return Q_OK;
}

/**
 * @brief   Output queue read.
 * @details A byte value is read from the low end of an output queue.
 *
 * @param[in] oqp       pointer to an @p output_queue_t structure
 * @return              The byte value from the queue.
 * @retval Q_EMPTY      if the queue is empty.
 *
 * @iclass
 */
msg_t oqGetI(output_queue_t *oqp) {
  uint8_t b;

  osalDbgCheckClassI();

  if (oqIsEmptyI(oqp))
    return Q_EMPTY;

  oqp->q_counter++;
  b = *oqp->q_rdptr++;
  if (oqp->q_rdptr >= oqp->q_top)
    oqp->q_rdptr = oqp->q_buffer;

  osalThreadDequeueNextI(&oqp->q_waiting, Q_OK);

  return b;
}

/**
 * @brief   Output queue write with timeout.
 * @details The function writes data from a buffer to an output queue. The
 *          operation completes when the specified amount of data has been
 *          transferred or after the specified timeout or if the queue has
 *          been reset.
 * @note    The function is not atomic, if you need atomicity it is suggested
 *          to use a semaphore or a mutex for mutual exclusion.
 * @note    The callback is invoked after writing each character into the
 *          buffer.
 *
 * @param[in] oqp       pointer to an @p output_queue_t structure
 * @param[out] bp       pointer to the data buffer
 * @param[in] n         the maximum amount of data to be transferred, the
 *                      value 0 is reserved
 * @param[in] time      the number of ticks before the operation timeouts,
 *                      the following special values are allowed:
 *                      - @a TIME_IMMEDIATE immediate timeout.
 *                      - @a TIME_INFINITE no timeout.
 *                      .
 * @return              The number of bytes effectively transferred.
 *
 * @api
 */
size_t oqWriteTimeout(output_queue_t *oqp, const uint8_t *bp,
                      size_t n, systime_t time) {
  qnotify_t nfy = oqp->q_notify;
  size_t w = 0;

  osalDbgCheck(n > 0);

  osalSysLock();
  while (TRUE) {
    while (oqIsFullI(oqp)) {
      if (osalThreadEnqueueTimeoutS(&oqp->q_waiting, time) != Q_OK) {
        osalSysUnlock();
        return w;
      }
    }
    oqp->q_counter--;
    *oqp->q_wrptr++ = *bp++;
    if (oqp->q_wrptr >= oqp->q_top)
      oqp->q_wrptr = oqp->q_buffer;

    if (nfy)
      nfy(oqp);

    osalSysUnlock(); /* Gives a preemption chance in a controlled point.*/
    w++;
    if (--n == 0)
      return w;
    osalSysLock();
  }
}

#endif /* !defined(_CHIBIOS_RT_) || !CH_USE_QUEUES */

/** @} */