ref: d6185567e2757c9bd74defdfe7f227e59f2d6cd2
dir: /src/adpcms.h/
typedef struct adpcm_struct { int last_output; int step_index; int max_step_index; int const * steps; int mask; } * adpcm_t; int adpcm_decode(int code, adpcm_t state); /* 4-bit -> 16-bit */ int adpcm_encode(int sample, adpcm_t state); /* 16-bit -> 4-bit */ void adpcm_init(adpcm_t state, int type /* 0:IMA, 1:OKI */);