#include <u.h>#include <libc.h>#include <draw.h> /* * XOVFL protects the unitsperline() calculation, and its * limit is based on: * 	-2³¹ ≤	r.max.x*32 + r.min.x*32	< 2³¹ * 	-2²⁶ ≤	r.max.x + r.min.x	< 2²⁶ * 	-2²⁵ ≤	r.min.x, r.max.x	< 2²⁵ * for the worst case scenario where the depth is 32 and one of * the values is negative. * * YOVFL is meant to protect against overflow when * calculating the Memimage.zero and byteaddr(2) offsets.  Its * limit is derived from: * 	-2³¹ ≤	p.y*4*wpl + p.x*depth/8	< 2³¹ * 	-2³⁰ ≤	p.y*4*wpl		< 2³⁰ *	-2²⁸ ≤	p.y*wpl			< 2²⁸ * for the worst case scenario where both coordinates have the * same sign and wpl = Dx(r). */#define XOVFL(p)	((p).x < -(1<<25) || (p).x >= (1<<25))#define YOVFL(y)	((y) < -(1<<28) || (y) >= (1<<28)) /* * check for zero, negative size or insanely huge rectangle. */intbadrect(Rectangle r){	int x, y, zy0, zy1;	uint z; 	x = Dx(r);	y = Dy(r);	if(x > 0 && y > 0){		if(XOVFL(r.min) || XOVFL(r.max))			return 1;		z = x*y;		zy0 = x*r.min.y;		zy1 = x*r.max.y;		if(z/x == y		&& zy0/x == r.min.y && !YOVFL(zy0)		&& zy1/x == r.max.y && !YOVFL(zy1))			return 0;	}	return 1;}