/* Reduced from linuxdoom-1.10's p_maputl.c (GPLv2).  */

typedef int fixed_t;

enum
{
    BOXTOP,
    BOXBOTTOM,
    BOXLEFT,
    BOXRIGHT
};

typedef struct
{
    fixed_t x;
    fixed_t y;
} vertex_t;

typedef enum
{
    ST_HORIZONTAL,
    ST_VERTICAL,
    ST_POSITIVE,
    ST_NEGATIVE
} slopetype_t;

typedef struct line_s
{
    vertex_t* v1;
    /* [...snip...] */

    fixed_t dx;
    fixed_t dy;

    /* [...snip...] */
    slopetype_t slopetype;
    /* [...snip...] */
} line_t;

int P_PointOnLineSide (fixed_t x, fixed_t y, line_t* line);

int
P_BoxOnLineSide
( fixed_t*	tmbox,
  line_t*	ld )
{
    int		p1;
    int		p2;
	
    switch (ld->slopetype)
    {
      case ST_HORIZONTAL:
	p1 = tmbox[BOXTOP] > ld->v1->y;
	p2 = tmbox[BOXBOTTOM] > ld->v1->y;
	if (ld->dx < 0)
	{
	    p1 ^= 1;
	    p2 ^= 1;
	}
	break;
	
      case ST_VERTICAL:
	p1 = tmbox[BOXRIGHT] < ld->v1->x;
	p2 = tmbox[BOXLEFT] < ld->v1->x;
	if (ld->dy < 0)
	{
	    p1 ^= 1;
	    p2 ^= 1;
	}
	break;
	
      case ST_POSITIVE:
	p1 = P_PointOnLineSide (tmbox[BOXLEFT], tmbox[BOXTOP], ld);
	p2 = P_PointOnLineSide (tmbox[BOXRIGHT], tmbox[BOXBOTTOM], ld);
	break;
	
      case ST_NEGATIVE:
	p1 = P_PointOnLineSide (tmbox[BOXRIGHT], tmbox[BOXTOP], ld);
	p2 = P_PointOnLineSide (tmbox[BOXLEFT], tmbox[BOXBOTTOM], ld);
	break;
    }

    if (p1 == p2) /* { dg-bogus "use of uninitialized value" } */
	return p1; /* { dg-bogus "use of uninitialized value" } */
    return -1;
}