UpdateScreen.C

// Old UpdateScreen with bad CGA snow
/* extern void UpdateScreen(void);
#pragma aux UpdateScreen =  \
    "mov si, ScreenBuff"    \
    "mov di, 00h"           \
    "mov ax, [ScreenSeg]"   \
    "mov es, ax"            \
    "mov cx, SCREEN_SIZE"   \
    "rep movsw"             \
    modify [ax cx si di es]; */

// This one should reduce CGA snow
extern void UpdateScreen(void);
#pragma aux UpdateScreen =  \
    "mov si, ScreenBuff"    \
    "mov di, 00h"           \
    "mov ax, [ScreenSeg]"   \
    "mov es, ax"            \
    "mov cx, SCREEN_SIZE"   \
    "mov dx, 03DAh"         \
    "_blk:"                 \
    "in al, dx"             \
    "test al, 9"            \
    "jz _blk"               \
    "movsw"                 \
    "movsw"                 \
    "movsw"                 \
    "movsw"                 \
    "sub cx, 4"             \
    "jnz _blk"              \
    modify [ax cx dx si di es];