prime/include/Kyoto/Audio/g721.h

#ifndef _G721
#define _G721

struct g72x_state {
  long yl;   /* Locked or steady state step size multiplier. */
  short yu;  /* Unlocked or non-steady state step size multiplier. */
  short dms; /* Short term energy estimate. */
  short dml; /* Long term energy estimate. */
  short ap;  /* Linear weighting coefficient of 'yl' and 'yu'. */

  short a[2];  /* Coefficients of pole portion of prediction filter. */
  short b[6];  /* Coefficients of zero portion of prediction filter. */
  short pk[2]; /*
                * Signs of previous two samples of a partially
                * reconstructed signal.
                */
  short dq[6]; /*
                * Previous 6 samples of the quantized difference
                * signal represented in an internal floating point
                * format.
                */
  short sr[2]; /*
                * Previous 2 samples of the quantized difference
                * signal represented in an internal floating point
                * format.
                */
  char td;     /* delayed tone detect, new in 1988 version */
};

void g72x_init_state(struct g72x_state* state_ptr);

int g721_decoder(int i, struct g72x_state* state_ptr);

#endif // _G721