/*
 *   SIDDEMO.C, ÖERSION 2
 *
 *   ÆOR THE Ã-64 AND Ã-ÐOWER. 
 *
 *   BY: ÓTEVE ÒEISMAN
 *       50 ÄAVID ÃOURT
 *       ÄAYTON, ÎÊ 08810
 *       ATTMAIL!SREISMAN
 *
 *   ÐROGRAM IS BASED ON:
 *       "ÍÕÓÉÃ2"
 *       ÁÈÏÙ ÍAGAZINE, ÊUNE 1986
 *
 *   ÕNLIKE VERSION 1, THIS DEMO CONSISTANTLY
 *   PLAYS FULL, CRISP NOTES.
 *   
 *   ÐROGRAM DEMONSTRATES SEVERAL DISCRETE 
 *   CONCEPTS WHILE HARNESSING A POWERFUL
 *   FEATURE OF THE Ã-64; SOUND GENERATION.
 *   
 *   1.  ÆROM Ã, THE Ã64'S NORMAL INTERRUPT PROCESSING
 *       IS DYNAMICALLY ALTERED TO PERFORM AN INDEPENDENT
 *       MACHINE LANGUAGE BASED ROUTINE.  ÉN THIS CASE,
 *       A TIGHT 6502 ROUTINE TIMES EACH NOTE'S PLAY
 *       WITHOUT REGARD TO ANYTHING ELSE GOING ON.
 *   
 *   2.  ÔHE KEYBOARD IS ACCESSED DIRECTLY AND WITHOUT
 *       ANY COSTLY OVERHEAD.  ÇRANTED THAT THE KEY'S SCAN
 *       CODE ONLY IS RETURNED, BUT THE METHOD HAS MANY
 *       PRACTICAL APPLICATIONS FOR OTHER SOFTWARE.
 *   
 *   3.  ÔHE EMPLOYED ÍÌ ROUTINES, UNLIKE THE EARLIER VERSION
 *       OF THIS PROGRAM, ARE STATIONARY.  ÔHEY ARE NO LONGER
 *       POKED ELSEWHERE IN ÒÁÍ.  ÔHEIR ADDRESSES ARE CULLED
 *       FOR SYS() CALLS USING POINTERS AND INDIRECTION.
 *   
 *   4.  ÌASTLY, THE PROGRAM EMPLOYS THE GOOD SENSE OF
 *       CLEANING-UP AFTER ITSELF (THOUGH ONE LAST BUG
 *       LINGERS ON HERE; YOU'LL SEE IT WHEN YOU END
 *       PRACTICING YOUR TUNES).
 *   
 *   ÙOUR COMMENTS WILL BE APPRECIATED.  ÄROP ME A LINE AT
 *   MY ADDRESS (LISTED ABOVE), OR THROUGH THE ÐÒÏ-ÌÉÎÅ BBS.
 *   
 *   ÈAVE FUN!
 */

#INCLUDE <STDIO.H>

#DEFINE PEEK(X) *((CHAR *)X)
#DEFINE POKE(X,Y) *((CHAR *)X)=Y

#DEFINE ÓÆÄØ   0XÃÂ     /* ËEYBOARD SCAN CODE TAKEN */
                        /* FROM HERE.               */

#DEFINE ÔÉÍÅÒ  0XÆÂ     /* ZERO-PAGE VARIABLE/FIELD */

#DEFINE ÕÓÒÁÄ1 0X311
#DEFINE ÕÓÒÁÄ2 0X312
#DEFINE ÃÉÎÖ1  0X314
#DEFINE ÃÉÎÖ2  0X315

#DEFINE ÓÉÄ    0XÄ400
#DEFINE ÆÒÅÌÏ1 0XÄ400
#DEFINE ÆÒÅÈÉ1 0XÄ401
#DEFINE Ð×ÌÏ1  0XÄ402
#DEFINE Ð×ÈÉ1  0XÄ403
#DEFINE ÖÃÒÅÇ1 0XÄ404
#DEFINE ÁÔÄÃÙ1 0XÄ405
#DEFINE ÓÕÒÅÌ1 0XÄ406
#DEFINE ÓÉÇÖÏÌ 0XÄ418

/* ËEYBOARD SCAN CODES FOR PROGRAM'S VALID KEYS.
 */
STATIC  CHAR MATRIX[] =
         Û62,10, 9,13,18,17,21,22,26,29,30,
          34,33,37,38,42,45,46,50,49,53 Ý;

/* ÆREQUENCY TABLES FOR PIANO NOTES USED HEREIN
 * Æ/Ù/É - THE SID CHIP USED A 12-BIT VALUE FOR
 *         A DESIRED FREQUENCY.  ÔHE HIFREQ VALUES
 *         ARE PLACED INTO THE REQUIRED NYBBLE,
 *         AND THE LOFREQ'S ARE PLACED AS WHOLE
 *         BYTES.
 */
STATIC  CHAR HIFREQ[] =
         Û13,14,14,15,16,17,18,19,21,22,23,25,
          26,28,29,31,33,35,37,39,42 Ý;

STATIC  CHAR LOFREQ[] =
         Û 78,24,239,210,195,195,209,239,31,96,181,
           30,156,49,223,165,135,134,162,223,62 Ý;

/* ÔHIS ÍÌ IS USED TO TIME NOTE DURATION.
 */
STATIC  CHAR ML[] =
         Û
          0XÁ6,0XÆÂ,      /* ×ÁÉÔ  LDX ÔÉÍÅÒ      */
          0XÃÁ,           /*       DEX            */
          0XÄ0,0X07,      /*       BNE ÒÔÒÎ       */
          0XÁ9,0X40,      /*       LDA #64        */
          0X8Ä,0X04,0XÄ4, /*       STA ÖÃÒÅÇ1     */
          0XÁ2,0X00,      /*       LDX #0         */
          0X86,0XÆÂ,      /* ÒÔÒÎ  STX ÔÉÍÅÒ      */
          0X6Ã,0X11,0X03, /* ÊÍÐ   JMP (ÕÓÒÁÄ1/2) */
          0X00            /*       BRK            */
         Ý;

/* ÆOLLOWING ARE TWO EXTREMELY SHORT ML ROUTINES
 * CALLED WITH SYS() TO DISABLE AND THEN RE-ENABLE
 * THE 64'S INTERRUPT MACHINE.
 * ÔHE POINTER FIELDS ARE USED TO SYS() TO THE ML.
 */

STATIC  CHAR SEI[] =Û 0X78,0X60 Ý;
STATIC  CHAR CLI[] =Û 0X58,0X60 Ý;
        CHAR *SEIRTN, *CLIRTN, *MLRTN;

MAIN()
Û
REGISTER INT   I;
STATIC   CHAR  C;
STATIC   CHAR  CC;
         CHAR  DMY;
UNSIGNED INT   ML¤ADR, ML¤LO, ML¤HI;
         
         /* ÓET UP INTERRUPT VECTOR.
          *
          * ÆIRST, GET CURRENT ÉÒÑ VECTOR BYTE
          * AND INSERT INTO ÕÓÅÒ VECTOR. 
          */
         C = PEEK(ÃÉÎÖ1);
         POKE(ÕÓÒÁÄ1, C);

         C = PEEK(ÃÉÎÖ2);
         POKE(ÕÓÒÁÄ2, C);

         /* ÒETRIEVE AND CONVERT ADDRESS
          * FOR ARITHMETIC OPERATIONS.
          * ÒESULTS ARE USED FOR SETTING
          * A NEW ÃÉÎÖ VECTOR.
          */
         SEIRTN = &SEI[0];
         CLIRTN = &CLI[0];
         MLRTN  = &ML[0];
         ML¤ADR = MLRTN;
         ML¤HI  = ML¤ADR / 256;
         ML¤LO  = ML¤ADR - (ML¤HI * 256);

         /* ÒESET ÃÉÎÖ FOR NEW VECTOR.
          */
         SYS(SEIRTN, &DMY, &DMY, &DMY);
         POKE(ÃÉÎÖ1, ML¤LO);
         POKE(ÃÉÎÖ2, ML¤HI);
         SYS(CLIRTN, &DMY, &DMY, &DMY);

         /* ÉNITIALIZE AND LOAD SID FOR DEMO.
          */
         POKE(ÔÉÍÅÒ, 60);
         CLSID();
         POKE( ÓÉÇÖÏÌ, 15 );
         POKE( ÁÔÄÃÙ1,  9 );
         POKE( ÓÕÒÅÌ1,  0 );
         POKE( Ð×ÈÉ1,   0 );
         POKE( Ð×ÌÏ1, 255 );
         POKE( ÖÃÒÅÇ1, 64 );

         MAPOUT();         /* DISPLAY INSTRUCTIONS      */
         CC = 0X00;        /* INITIALIZE ÌAST-ËEY-ÈIT   */

         /* ÍAINLINE ROUTINE; PLAY THE KEYS.
          * ÅSCAPE BY PRESSING 'X';
          */
ÌÏÏÐ:
         C = PEEK(ÓÆÄØ);   /* GET SCAN CODE             */
         IF(C == 0X40)Û    /* 0X40 = 'ÎO ËEY ÐRESSED    */
             CC = 0X00;    /* UPDATE ÌAST-ËEY-ÈIT       */
             GOTO ÌÏÏÐ;
         Ý
         IF(C == 0X17)Û    /* 0X17 IS SCAN CODE FOR 'X' */
             MOPUP();
             EXIT(0);
         Ý
         IF(C == CC)                   /* KEY MUST BE LIFTED ..  */
             GOTO ÌÏÏÐ;                /* .. TO PLAY IT AGAIN    */
         FOR(I=0; I<21; I++)Û          /* SEARCH FOR A VALID KEY */
             IF(C == MATRIX[I])Û       /* GOT ONE; PLAY IT       */
                 CC = C;               /* UPDATE ÌAST-ËEY-ÈIT    */
                 POKE(ÔÉÍÅÒ,  60);
                 POKE(ÖÃÒÅÇ1, 64);          /* TURN ÖOICE-1 OFF  */
                 POKE(ÆÒÅÈÉ1, HIFREQ[I]);   /* ÓET FREQUENCY     */
                 POKE(ÆÒÅÌÏ1, LOFREQ[I]);
                 POKE(ÖÃÒÅÇ1, 65);          /* TURN ÖOICE-1 ON   */
                 GOTO ÌÏÏÐ;
             Ý
         Ý
         GOTO ÌÏÏÐ;
Ý

CLSID()
Û
REGISTER INT I;
  
         FOR(I = 0; I < 24; I++)
             POKE(ÓÉÄ + I, 0);
Ý

MAPOUT()
Û
         PUTCHAR(147);
         PUTCHAR('\N');
         PUTCHAR('\N');
         PUTS(" ÓÉÄÄÅÍÏ.Ã -- Á DEMO PIANO PLAYER");
         PUTCHAR('\N');
         PUTCHAR('\N');
         PUTCHAR('\N');
         PUTS("          ÕSE INDICATED KEYS.");
         PUTCHAR('\N');
         PUTCHAR('\N');
         PUTS("ÂÌÁÃË ËÅÙÓ Ñ× ÒÔ ÕÉÏ @*");
         PUTS("  NOTES -> GA CD FGA CD");
         PUTS("           ## ## ### ##");
         PUTCHAR('\N');                   
         PUTS("×ÈÉÔÅ ËÅÙÓ  ÁÓÄÆÇÈÊËÌ:;=");
         PUTS("  NOTES ->  ABCDEFGABCDE");  
         PUTCHAR('\N');
         PUTCHAR('\N');
         PUTS("          ÂEGIN NOW.  ÅNJOY!");
         PUTCHAR('\N');
         PUTS("          ÐRESS <X> TO EXIT."); 
Ý

MOPUP()
Û
CHAR C, DMY;

         SYS(SEIRTN, &DMY, &DMY, &DMY);     /* DISABLE INTERUPTS       */
         C = PEEK(ÕÓÒÁÄ1);                  /* RESTORES                */
         POKE(ÃÉÎÖ1, C);                    /*        TO               */
         C = PEEK(ÕÓÒÁÄ2);                  /*         ORIGINAL        */
         POKE(ÃÉÎÖ2, C);                    /*                VECTORS  */
         SYS(CLIRTN, &DMY, &DMY, &DMY);     /* ENABLE INTERRUPTS       */
         CLSID();                           /* ZAP ÓÉÄ'S REGISTERS     */
Ý
/* END */