C64-dev/vim/mltest.pet

/* MLTEST.C - PROVE CALLING MACHINE CODE FROM ÐOWER Ã, ONE MARKED STEP AT A TIME.
 * ×HATEVER IS LEFT ON SCREEN WHEN IT HANGS IS THE LAST STEP THAT WORKED. */

CHAR TXT[8];
CHAR RTS[4];

MAIN()
Û
    CHAR *P;
    CHAR A, X, Y;

    P = (CHAR *) 0X0400;
    P[0] = 1;                       /* Á: MAIN STARTED */

    RTS[0] = 96;                    /* ÒÔÓ */
    A = 0;
    X = 0;
    Y = 0;
    P[1] = 2;                       /* Â: ABOUT TO SYS() A BARE ÒÔÓ */
    FOR (;;) Û Ý
    SYS(15, (UNSIGNED) RTS, &A, &X, &Y);
    P[2] = 3;                       /* Ã: SYS + ARRAY ADDRESS WORK */

    TXT[0] = 72;
    TXT[1] = 69;
    TXT[2] = 76;
    TXT[3] = 76;
    TXT[4] = 79;
    MLROW((UNSIGNED) TXT, 5, 1104, 2, 0);
    P[3] = 4;                       /* Ä: THE REAL ROUTINE CAME BACK */
    FOR (;;) Û Ý
Ý