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1 ---- How to write your own audio driver for ft2play ----
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2
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3 1) Include the header "../../pmp_mix.h"
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4
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5 2) Implement the following functions using your audio API of choice:
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6
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7 void lockMixer(void); // waits for the current mixing block to finish and disables further mixing
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8 void unlockMixer(void); // enables mixing again
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9 bool openMixer(int32_t mixingFrequency, int32_t mixingBufferSize); // 8000..96000, 256..8192 (true if ok, false if fail)
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10 void closeMixer(void);
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11
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12 3) When the audio API is requesting samples, make a call to mix_UpdateBuffer(), f.ex.:
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13
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14 mix_UpdateBuffer((int16_t *)stream, len / 4);
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15
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16 4) Make your own preprocessor define (f.ex. AUDIODRIVER_ALSA) and pass it to the compiler during compilation
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17 (also remember to add the correct driver .c file to the compilation script)
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18
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19 5) In "pmplay.h", insert your preprocessor define and include in the "AUDIO DRIVERS" #ifdef chain and
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20 include your audio driver header in there.
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21
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22 NOTE:
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23 lockMixer() should be implemented in a way where you wait until the mix_UpdateBuffer() call has finished (important),
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24 then you block further calls to mix_UpdateBuffer() until the mixer is unlocked again.
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25 You should not send zeroes to the audio device while it's locked, as the lock/unlock pairs are usually called within
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26 a very short time frame anyway.
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27
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28 -------------------------------------------------------
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29
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30 You can look at audiodrivers/sdl/sdldriver.c if you need some references...
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