ref: 49ff67154a0150cade077dcd040d68bc6a200b17
dir: /h/line.h/
typedef struct { SPFLOAT a, dur, b; SPFLOAT val, incr; uint32_t sdur, stime; int init; } sp_line; int sp_line_create(sp_line **p); int sp_line_destroy(sp_line **p); int sp_line_init(sp_data *sp, sp_line *p); int sp_line_compute(sp_data *sp, sp_line *p, SPFLOAT *in, SPFLOAT *out);