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//------------------------------------------------------------------------------
/// \unit
///
/// !!!Purpose
/// 
/// This module provides definitions and functions for using the AC'97
/// controller (AC97C).
/// 
/// !!!Usage
/// 
/// -# Enable the AC'97 interface pins (see pio & board.h).
/// -# Configure the AC'97 controller using AC97C_Configure
/// -# Assign the input and output slots to channels, and the data size used to
///    transfer AC97 data stream.
///    - Three functions can be used:
///       - AC97C_AssignInputSlots: set slots for AC'97 data in, recording.
///       - AC97C_AssignOutputSlots: set slots for AC'97 data out, playing.
///       - AC97C_SetChannelSize: set data sizes in bits for AC'97 data stream.
///    - Three different channels can be configured:
///       - AC97C_CHANNEL_CODEC: AC'97 register access channel, its size is
///         fixed and #must not# change by AC97C_SetChannelSize
///       - AC97C_CHANNEL_A: AC'97 stream channel, with PDC support.
///       - AC97C_CHANNEL_B: AC'97 data channel, without PDC support.
/// -# Configure the used AC97 channel with AC97C_ConfigureChannel, to enable
///    the channel.
/// -# Then you can operate the connected AC'97 codec:
///    - AC97C_ReadCodec / AC97C_WriteCodec: Read / Write codec register.
///    - AC97C_Transfer: Transfer through AC97C channels to setup codec register
///     or transfer %audio data stream.
///       - AC97C_CODEC_TRANSFER: access the codec register.
///       - AC97C_CHANNEL_A_RECEIVE, AC97C_CHANNEL_B_RECEIVE: start reading.
///       - AC97C_CHANNEL_A_TRANSMIT, AC97C_CHANNEL_B_TRANSMIT: start writing.
///    Normally you can initialize a set of AC'97 codec registers to initialize
///    the codec for %audio playing and recording.
/// -# Example code for playing & recording:
///    - General process:
///       -# Configure the codec registers for the %audio settings and formats;
///       -# Setup the channel size if necessery;
///       -# Start %audio stream transfer.
///    - Audio playing sample:
/// \code
///    // Configure sample rate of codec
///    AC97C_WriteCodec(AD1981B_PMC_DAC, expectedSampleRate);
///    // Set channel size
///    AC97C_SetChannelSize(AC97C_CHANNEL_A, bitsPerSample);
///    // Start channel A transfer
///    AC97C_Transfer(AC97C_CHANNEL_A_TRANSMIT, 
///                   (unsigned char *) (pointerToAudioDataBuffer),
///                   numberOfSamplesToSend,
///                   (Ac97Callback) PlayingFinished, 
///                   0);
/// \endcode
///    - Audio recording sample:
/// \code
///    // Enable recording
///    AC97C_WriteCodec(AD1981B_REC_SEL, 0);
///    // Set sample rate
///    AC97C_WriteCodec(AD1981B_PMC_ADC, 7000);
///    // Always use 16-bits recording
///    AC97C_SetChannelSize(AC97C_CHANNEL_A, 16);
///    // Start recording
///    AC97C_Transfer(AC97C_CHANNEL_A_RECEIVE, 
///                   (unsigned char *) RECORD_ADDRESS,
///                   MAX_RECORD_SIZE,
///                   (Ac97Callback) RecordFinished,
///                   0);
/// \endcode
//------------------------------------------------------------------------------

#ifndef AC97C_H
#define AC97C_H

//------------------------------------------------------------------------------
//         Constants
//------------------------------------------------------------------------------

/// The channel is already busy with a transfer.
#define AC97C_ERROR_BUSY            1
/// The transfer has been stopped by the user.
#define AC97C_ERROR_STOPPED         2

/// Codec channel index.
#define AC97C_CHANNEL_CODEC         0
/// Channel A index.
#define AC97C_CHANNEL_A             1
/// Channel B index.
#define AC97C_CHANNEL_B             2

/// Codec transmit/receive transfer index.
#define AC97C_CODEC_TRANSFER        0
/// Channel A receive transfer index.
#define AC97C_CHANNEL_A_RECEIVE     1
/// Channel A transmit transfer index.
#define AC97C_CHANNEL_A_TRANSMIT    2
/// Channel B receive transfer index.
#define AC97C_CHANNEL_B_RECEIVE     3
/// Channel B transmit transfer index.
#define AC97C_CHANNEL_B_TRANSMIT    4

//------------------------------------------------------------------------------
//         Types
//------------------------------------------------------------------------------

/// AC97C transfer callback function.
typedef void (*Ac97Callback)(void *pArg,
                             unsigned char status,
                             unsigned int remaining);

//------------------------------------------------------------------------------
//         Exported functions
//------------------------------------------------------------------------------

extern void AC97C_Configure();

extern void AC97C_ConfigureChannel(unsigned char channel, unsigned int cfg);

extern void AC97C_AssignInputSlots(unsigned char channel, unsigned int slots);

extern void AC97C_AssignOutputSlots(unsigned char channel, unsigned int slots);

extern unsigned char AC97C_Transfer(
                unsigned char channel,
                unsigned char *pBuffer,
                unsigned int numSamples,
                Ac97Callback callback,
                void *pArg);

extern unsigned char AC97C_IsFinished(unsigned char channel);

extern void AC97C_WriteCodec(unsigned char address, unsigned short data);

extern unsigned short AC97C_ReadCodec(unsigned char address);

extern void AC97C_SetChannelSize(unsigned char channel, unsigned char size);

extern void AC97C_CancelTransfer(unsigned char channel);

#endif //#ifndef AC97C_H