ref: 9211d95a76975169ee7b71fc74582e5707e3fa04
dir: /h/buthp.h/
typedef struct { SPFLOAT freq; SPFLOAT lfreq; SPFLOAT a[7]; SPFLOAT pidsr; } sp_buthp; int sp_buthp_create(sp_buthp **p); int sp_buthp_destroy(sp_buthp **p); int sp_buthp_init(sp_data *sp, sp_buthp *p); int sp_buthp_compute(sp_data *sp, sp_buthp *p, SPFLOAT *in, SPFLOAT *out);