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116 lines
3.5 KiB
C
116 lines
3.5 KiB
C
/**
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* \file
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* <!--
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* This file is part of BeRTOS.
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*
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* Bertos is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* As a special exception, you may use this file as part of a free software
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* library without restriction. Specifically, if other files instantiate
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* templates or use macros or inline functions from this file, or you compile
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* this file and link it with other files to produce an executable, this
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* file does not by itself cause the resulting executable to be covered by
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* the GNU General Public License. This exception does not however
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* invalidate any other reasons why the executable file might be covered by
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* the GNU General Public License.
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*
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* Copyright 2009 Develer S.r.l. (http://www.develer.com/)
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*
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* -->
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*
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* \brief I2S driver functions.
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*
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* This driver uses a double buffering technique to keep i2s bus busy. First fill in the two buffers
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* using i2s_getBuffer(), then start audio playing with i2s_start(). Then call i2s_getFreeBuffer()
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* until you have finished your samples. The reproduction will automatically stop if you don't
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* call i2s_getFreeBuffer() frequently enough.
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*
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* Example:
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* \code
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* // fill in the buffers before start
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* buf = i2s_getBuffer(I2S_FIRST_BUF);
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* // ...
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* buf = i2s_getBuffer(I2S_SECOND_BUF);
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* // ...
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* // here the driver will play only the first two buffers...
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* i2s_start();
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* // ...call getFreeBuffer() to continue playing.
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* while (!(buf = i2s_getFreeBuffer()))
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* ;
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* // now fill the buffer again
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* \endcode
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*
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* \author Luca Ottaviano <lottaviano@develer.com>
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*
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* $WIZ$ module_name = "i2s"
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* $WIZ$ module_configuration = "bertos/cfg/cfg_i2s.h"
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* $WIZ$ module_supports = "at91"
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*/
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#ifndef DRV_I2S_AT91_H
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#define DRV_I2S_AT91_H
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#include <cfg/compiler.h>
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#include <cfg/macros.h>
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#include <io/arm.h>
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/**
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* First buffer.
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*/
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#define I2S_FIRST_BUF 0
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/**
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* Second buffer.
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*/
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#define I2S_SECOND_BUF 1
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/**
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* Initializes the module and sets current buffer to I2S_FIRST_BUF.
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*/
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void i2s_init(void);
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/**
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* Returns one of the two buffers or NULL if none is available.
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*
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* You can't call this function if you have already started the player.
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* \param buf_num The number of the buffer, ie I2S_FIRST_BUF or I2S_SECOND_BUF.
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* \return A pointer to the buffer if the buffer is available (not full), 0 on errors
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*/
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uint8_t *i2s_getBuffer(unsigned buf_num);
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/**
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* Returns a buffer that will be played after the current one.
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*
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* You should fill it faster than your reproduction time. You can't call this function
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* if the player is not running
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* \return The next buffer to be played, 0 if both are busy.
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*/
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uint8_t *i2s_getFreeBuffer(void);
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/**
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* Starts playing from I2S_FIRST_BUFFER.
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*
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* You must have filled both buffers before calling this function. Does nothing if already playing.
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* \return false on errors, true otherwise.
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*/
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bool i2s_start(void);
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INLINE bool i2s_isPlaying(void)
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{
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return !(SSC_SR & BV(SSC_TXEMPTY));
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}
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#endif /* DRV_I2S_AT91_H */
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