#include <u.h>#include <libc.h>#include <libg.h> #define	CHUNK	4096 voidwrbitmapfile(int fd, Bitmap *b){	char hdr[5*12+1];	uchar *data;	long dy, px;	ulong l, t, n;	long miny, maxy; 	sprint(hdr, "%11d %11d %11d %11d %11d ",		b->ldepth, b->r.min.x, b->r.min.y, b->r.max.x, b->r.max.y);	if(write(fd, hdr, 5*12) != 5*12)		berror("wrbitmapfile write"); 	px = 1<<(3-b->ldepth);	/* pixels per byte */	/* set l to number of bytes of data per scan line */	if(b->r.min.x >= 0)		l = (b->r.max.x+px-1)/px - b->r.min.x/px;	else{	/* make positive before divide */		t = (-b->r.min.x)+px-1;		t = (t/px)*px;		l = (t+b->r.max.x+px-1)/px;	}	miny = b->r.min.y;	maxy = b->r.max.y;	data = malloc(CHUNK);	if(data == 0)		berror("wrbitmapfile malloc");	while(maxy > miny){		dy = maxy - miny;		if(dy*l > CHUNK)			dy = CHUNK/l;		rdbitmap(b, miny, miny+dy, data);		n = dy*l;		if(write(fd, data, n) != n){			free(data);			berror("wrbitmapfile write");		}		miny += dy;	}	free(data);}