Allow arbitrary numbers of columns for VNC server screen resolution.

The prior code only allowed multiples of 32 for the
numbers of columns. Remove this restriction to allow
a forthcoming UEFI firmware update to allow arbitrary
x,y resolutions.

(the code for handling rows already supported non mult-32 values)

Reviewed by:	Leon Dang (original author)
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D15274

usr.sbin/bhyve/rfb.c

@@ -541,16 +541,21 @@ rfb_send_screen(struct rfb_softc *rc, int cfd, int all)
 		}
 
 		for (x = 0; x < xcells; x++) {
+			if (x == (xcells - 1) && rem_x > 0)
+				cellwidth = rem_x;
+			else
+				cellwidth = PIX_PER_CELL;
+
 			if (rc->hw_crc)
 				crc_p[x] = fast_crc32(p,
-				             PIX_PER_CELL * sizeof(uint32_t),
+				             cellwidth * sizeof(uint32_t),
 				             crc_p[x]);
 			else
 				crc_p[x] = (uint32_t)crc32(crc_p[x],
 				             (Bytef *)p,
-				             PIX_PER_CELL * sizeof(uint32_t));
+				             cellwidth * sizeof(uint32_t));
 
-			p += PIX_PER_CELL;
+			p += cellwidth;
 
 			/* check for crc delta if last row in cell */
 			if ((y & PIXCELL_MASK) == PIXCELL_MASK || y == (h-1)) {
@@ -563,28 +568,6 @@ rfb_send_screen(struct rfb_softc *rc, int cfd, int all)
 				}
 			}
 		}
-
-		if (rem_x) {
-			if (rc->hw_crc)
-				crc_p[x] = fast_crc32(p,
-				                    rem_x * sizeof(uint32_t),
-				                    crc_p[x]);
-			else
-				crc_p[x] = (uint32_t)crc32(crc_p[x],
-				                    (Bytef *)p,
-				                    rem_x * sizeof(uint32_t));
-			p += rem_x;
-
-			if ((y & PIXCELL_MASK) == PIXCELL_MASK || y == (h-1)) {
-				if (orig_crc[x] != crc_p[x]) {
-					orig_crc[x] = crc_p[x];
-					crc_p[x] = 1;
-					changes++;
-				} else {
-					crc_p[x] = 0;
-				}
-			}
-		}
 	}
 
 	/* If number of changes is > THRESH percent, send the whole screen */