userdelfx.h

/*
    BSD 3-Clause License

    Copyright (c) 2018, KORG INC.
    All rights reserved.

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    modification, are permitted provided that the following conditions are met:

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      list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.

    * Neither the name of the copyright holder nor the names of its
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      this software without specific prior written permission.

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    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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//*/

/**
 * @file    userdelfx.h
 * @brief   C interface header for user delay fx.
 *
 * @addtogroup fx Effects
 * @{
 *
 * @addtogroup delfx_inst Delay Effect Instance (delfx)
 * @{
 */

#ifndef __userdelfx_h
#define __userdelfx_h

#include <stdint.h>

#include "fx_api.h"
#include "userprg.h"

#ifdef __cplusplus
extern "C" {
#endif

  /**
   * This macro can be used to declare a memory buffer in SDRAM space.
   *
   * E.g.: float g_my_buffer[1024] __sdram;
   */
#define __sdram __attribute__((section(".sdram")))

  /**
   * User facing parameters
   */
  typedef enum {
    /** Time parameter */
    k_user_delfx_param_time = 0,
    /** Depth parameter */
    k_user_delfx_param_depth,
    k_user_delfx_param_reserved0,
    /** Alternative depth parameter, usually accessible via shift function */
    k_user_delfx_param_shift_depth,
    k_num_user_delfx_param_id
  } user_delfx_param_id_t;

  /** @private */
  typedef void (*UserDelFXFuncEntry)(uint32_t platform, uint32_t api);
  /** @private */
  typedef void (*UserDelFXFuncInit)(uint32_t platform, uint32_t api);
  /** @private */
  typedef void (*UserDelFXFuncProcess)(float *xn, uint32_t frames);
  /** @private */
  typedef void (*UserDelFXSuspend)(void);
  /** @private */
  typedef void (*UserDelFXResume)(void);
  /** @private */
  typedef void (*UserDelFXFuncParam)(uint8_t index, int32_t value);
  /** @private */
  typedef void (*UserDelFXFuncDummy)(void);

  /** @private */
#pragma pack(push, 1)
  typedef struct user_delfx_hook_table {
    uint8_t              magic[4];
    uint32_t             api;
    uint8_t              platform;
    uint8_t              reserved0[7];
    
    UserDelFXFuncEntry   func_entry;
    UserDelFXFuncProcess func_process;
    UserDelFXSuspend     func_suspend;
    UserDelFXResume      func_resume;
    UserDelFXFuncParam   func_param;
    UserDelFXFuncDummy   reserved1[7];
  } user_delfx_hook_table_t;
#pragma pack(pop)

  /** @private */
#pragma pack(push, 1)
  typedef struct user_delfx_data {
    user_prg_header_t       header;
    user_delfx_hook_table_t hooks;
    // code bytes following
  } user_delfx_data_t;
#pragma pack(pop)

  /**
   * @name    Core API
   * @{
   */

#define DELFX_INIT    __attribute__((used)) _hook_init 
#define DELFX_PROCESS __attribute__((used)) _hook_process
#define DELFX_SUSPEND __attribute__((used)) _hook_suspend
#define DELFX_RESUME  __attribute__((used)) _hook_resume
#define DELFX_PARAM   __attribute__((used)) _hook_param

  /** @private */
  void _entry(uint32_t platform, uint32_t api);

  /**
   * Initialization callback. Must be implemented by your custom effect.
   *
   * @param platform Current target platform/module. See userprg.h
   * @param api Current API version. See userprg.h
   */
  void _hook_init(uint32_t platform, uint32_t api);

  /**
   * Processing callback. Must be implemented by your custom effect.
   *
   * Delay effects must write back their result to the input buffer and are responsible for wet/dry mix balance.
   * Typically wet/dry balance should be controllable via the shift-depth parameter.
   *
   * @param xn Input/output sample buffer. 
   * @param frames Size of buffer in frames. (2 samples per frames)
   *
   * @note Implementation must support at least up to 64 frames.
   * @note Optimize for powers of two.
   */  
  void _hook_process(float *xn, uint32_t frames);

  /**
   * Suspend callback. Must be implemented by your custom effect.
   *
   * Called before effect gets suspended. While suspended the processing callback will not be called.
   */    
  void _hook_suspend(void);

  /**
   * Resume callback. Must be implemented by your custom effect.
   *
   * Called before calls to processing callback resume after being suspended.
   */    
  void _hook_resume(void);

  /**
   * Parameter change callback. Must be implemented by your custom effect.
   *
   * @param index Parameter ID. See user_delfx_param_id_t.
   * @param index Parameter value. 
   *
   * @note All parameters have 10 bit resolution.
   */
  void _hook_param(uint8_t index, int32_t value);

  /** @} */
  
#ifdef __cplusplus
} // extern "C"
#endif
  
#endif // __userdelfx_h

/** @} @} */