mboot.c32: fix the video mode selection algorithm

Make the video mode selection algorithm do what was intended...

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/com32/mboot/initvesa.c b/com32/mboot/initvesa.c
index 5452648..cf2707d 100644 (file)
--- a/com32/mboot/initvesa.c
+++ b/com32/mboot/initvesa.c
@@ -129,7 +129,6 @@ void set_graphics_mode(const struct multiboot_header *mbh,
 
        /* Must either be a packed-pixel mode or a direct color mode
           (depending on VESA version ); must be a supported pixel format */
-       pxf = 0;                /* Not usable */
 
        if (mi->bpp == 32 &&
            (mi->memory_layout == 4 ||
@@ -151,17 +150,25 @@ void set_graphics_mode(const struct multiboot_header *mbh,
                  (mi->memory_layout == 6 && mi->rpos == 10 && mi->gpos == 5 &&
                   mi->bpos == 0)))
            pxf = 15;
+       else
+           continue;
 
        better = false;
-
        err = abs(mi->h_res - wantx) + abs(mi->v_res - wanty);
 
+#define IS_GOOD(mi, bestx, besty) \
+       ((mi)->h_res >= (bestx) && (mi)->v_res >= (besty))
+
        if (!bestpxf)
            better = true;
-       else if ((vesa_info.mi.h_res < wantx || vesa_info.mi.v_res < wantx) &&
-                mi->h_res >= wantx && mi->v_res >= wanty)
+       else if (!IS_GOOD(&vesa_info.mi, wantx, wanty) &&
+                IS_GOOD(mi, wantx, wanty))
            /* This matches criteria, which the previous one didn't */
            better = true;
+       else if (IS_GOOD(&vesa_info.mi, wantx, wanty) &&
+                !IS_GOOD(mi, wantx, wanty))
+           /* This doesn't match criteria, and the previous one did */
+           better = false;
        else if (err < besterr)
            better = true;
        else if (err == besterr && (pxf == (int)mbh->depth || pxf > bestpxf))