/*
 * System Interface Library for games
 * Copyright (c) 2007-2020 Andrew Church <achurch@achurch.org>
 * Released under the GNU GPL version 3 or later; NO WARRANTY is provided.
 * See the file COPYING.txt for details.
 *
 * src/test/sound/wavegen.h: Header for wave generators.
 */

#ifndef SIL_SRC_TEST_SOUND_WAVEGEN_H
#define SIL_SRC_TEST_SOUND_WAVEGEN_H

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/* State buffer for square_gen() */
typedef struct SquareState SquareState;
struct SquareState {
    int period;       // Length of one cycle, in samples.
    int num_cycles;   // Number of cycles to generate.
    int samples_out;  // Number of samples generated so far.
};

/*-----------------------------------------------------------------------*/

/**
 * square_gen:  Generate a square wave at a given period and length.
 * The square wave has output +10000 for the first half of its cycle,
 * output -10000 for the second half.  (If the period is an odd number,
 * the midpoint sample will have value -10000.)
 *
 * [Parameters]
 *     handle: Audio data handle (SquareState pointer).
 *     pcm_buffer: Output buffer for PCM samples.
 *     pcm_len: Number of samples to retrieve.
 * [Return value]
 *     True on success, false on end of stream or error.
 */
extern int square_gen(void *handle, void *pcm_buffer, int pcm_len);

/**
 * stereo_square_gen:  Generate a stereo pair of square waves, with the
 * left channel at a given period and the right channel at twice that
 * period (half the frequency).
 *
 * [Parameters]
 *     handle: Audio data handle (SquareState pointer).
 *     pcm_buffer: Output buffer for PCM samples.
 *     pcm_len: Number of samples to retrieve.
 * [Return value]
 *     True on success, false on end of stream or error.
 */
extern int stereo_square_gen(void *handle, void *pcm_buffer, int pcm_len);

/**
 * sawtooth_gen:  Generate a sawtooth wave that cycles through all 16-bit
 * sample values: 0,1,...,32767,-32768,...,1,0,1,...
 *
 * [Parameters]
 *     handle: Audio data handle (pointer to int16_t: next sample value).
 *     pcm_buffer: Output buffer for PCM samples.
 *     pcm_len: Number of samples to retrieve.
 * [Return value]
 *     True on success, false on end of stream or error.
 */
extern int sawtooth_gen(void *handle, void *pcm_buffer, int pcm_len);

/**
 * sawtooth_gen:  Generate a stereo sawtooth wave whose PCM data is
 * identical to that generated by sawtooth_gen().  Consequently, the left
 * channel will have even values (0,2,4,..). and the right channel will
 * have odd values (1,3,5,...).
 *
 * [Parameters]
 *     handle: Audio data handle (pointer to int16_t: next sample value).
 *     pcm_buffer: Output buffer for PCM samples.
 *     pcm_len: Number of samples to retrieve.
 * [Return value]
 *     True on success, false on end of stream or error.
 */
extern int sawtooth_stereo_gen(void *handle, void *pcm_buffer, int pcm_len);

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#endif  // SIL_SRC_TEST_SOUND_WAVEGEN_H