fixed potentially reading out of bounds when doing banked blit to framebuffer

[retrobench] / src / dos / gfx.c

diff --git a/src/dos/gfx.c b/src/dos/gfx.c
index f7276af..939a679 100644 (file)
--- a/src/dos/gfx.c
+++ b/src/dos/gfx.c
@@ -247,7 +247,7 @@ void *set_video_mode(int idx, int nbuf)
                        vm->win_64k_step = 1 << vm->win_gran_shift;
                }
 
-               printf("  granularity: %dk (step: %d)\n", vm->win_gran, vm->win_64k_step);
+               printf("granularity: %dk (step: %d)\n", vm->win_gran, vm->win_64k_step);
        }
 
        /* allocate main memory framebuffer */
@@ -298,8 +298,7 @@ static void blit_frame_lfb(void *pixels, int vsync)
 
 static void blit_frame_banked(void *pixels, int vsync)
 {
-       int offs;
-       unsigned int pending;
+       int sz, offs, pending;
        unsigned char *pptr = pixels;
 
        if(vsync) wait_vsync();
@@ -308,10 +307,11 @@ static void blit_frame_banked(void *pixels, int vsync)
        offs = 0;
        pending = pgsize;
        while(pending > 0) {
-               //memcpy64((void*)0xa0000, pptr, 16384);
-               memcpy((void*)0xa0000, pptr, 65536);
-               pptr += 65536;
-               pending -= 65536;
+               sz = pending > 65536 ? 65536 : pending;
+               //memcpy64((void*)0xa0000, pptr, sz >> 3);
+               memcpy((void*)0xa0000, pptr, sz);
+               pptr += sz;
+               pending -= sz;
                offs += curmode->win_64k_step;
                vbe_setwin(0, offs);
        }