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Text File | 2004-01-01 | 6.0 KB | 260 lines

u S I D P L A Y E R P L U S SIDPlayer by Craig Chamberlain Plus by Dave Moorman Adding music to a program is not all that hard. Craig Chamberlain created SIDPlayer way back in the earliest days of the C-64. The code (in a file called SID.OBJ.64) is solid and has never failed me. The only problem I have had is remembering how to turn the bloody thing ON! The BASIC code is not that hard, just hard to remember. I often have to fine a BASIC program where SIDPlayer was used and dig out the code. I have now put it on the Encyclopedia Commodorea (on this issue), so you (and I) can easily find it. But my goodness! We are in the 21st Century. We shouldn't have to work that hard. Wouldn't it be neat to have a SIDPlayer Starter, where all you have to do is SYSaddr,loc? Well, I did it -- and the code is now a modulette in the MARM library. I will tell you about MARM later. For now, I have included M1.SID.ML on this issue. And it is truly sweet! You need to bload SID.OBJ.64 (to page 192) and your .MUS music file, of course. The bload M1.SID.ML to [any] safe open memory. The module is self-relocating, so you don't have to worry about using ML MOVE. In the accompanying demo, I moved the Top of BASIC down to page 128, then bloaded SID.OBJ.64 (to page 192), ZUKE1.MUS (to page 128), and M1.SID.ML (to page 140). M1.SID.ML must be initialized with SYS 140*256 This SYS literally finds where the code is in memory, and creates a jump table beginning at 832. You can see a list of available commands with SYS 140*256+3 Yep! The module is self-documented. That is the beauty of MARM. You will see +0 GETINT: LO>.A HI>.X +3 GETSTR: LEN>.A LO>.X HI>.Y +6 PUTINT: .A<LO .X<HI 251/2<VAR +9 PUTFLP: 251/2<.VAR ACCUM<VAL +12 PUTSTR:251/2<.VAR .A<LEN .X<LO .Y<HI +15 TIMES40:.A<LO .A>LO .X>HI These are ML routines to be used by any and all modulettes included in the package -- and not important unless you are creating a modulette. Then comes +18 STSID,LOC +21 ENDSIDONLY +24 KILLIRQ +27 FTSRE,PG These are the commands available to BASIC in this module. Note that each includes parameters, if any. To call the command, add the offset (+xx) to 832. Start SID --------- SYS 832+18,LOC where LOC is the location of the .MUS music data. In our demo, the music is at page 128, so the command to start the music is simply SYS832+18,128*256 And [voila!] the music starts. End SID Only ------------ SYS 832+21 When you use STARTSID, the current IRQ vector is tucked away in memory (828/829) and a flag is put at 830 -- before the SID is started. When you call this command, it checks for the flag, the replaces the previous vector. This will be useful if you are using SIDPlayer with another IRQ-driven routine (such as Mr.Mouse), and want to stop the music without killing the mouse. KILLIRQ ------- SYS 832+24 Then again, you might want to kill the mouse, and everything being driven by the IRQ. This will do it rather unceremoniously. Particularly good when the program is ended. FTSRE ----- SYS 832+27,PAGE where PAGE is the page where an FTS screen image file has been loaded. This is kind of a freebee. If you are using an FTS screen image file (created by Mr.MICK or SCRN2FONT), this call will put it on the screen exactly the way you designed it, including background and border color and text font and mode. This command assumes that you are using the default screen at page 4, and that your font is at page 8. MARM Moorman's --------- Adaptable Relocatable Module --------- ----------- ------ As mentioned often on this issue, the C-64 does not do relocatable ML code very easily. So, of course, my challenge was to make a module system where the code could be loaded to any open memory location and used immediately. We [can] write relocatable code in ML. The only restriction is that the coder must remember that the routine might be anywhere in memory. Therefore, we cannot use any JMP, JSR, Load, or Store to locations within the routine. These are all absolute addresses. But we can use relative branches and indirect addressing. And it is quite permissable to JMP or JSR to addresses outside the routine -- such as a JSR to the SIDPlayer. I wanted to use relocatable code to allow a programmer -- even a BASIC programmer -- to build a module containing only those command routines that would benefit the particular project at hand. The idea was to have a MARM Maker that would allow the programmer to custom build a module. That is the Adaptable part of the name. And, since each such module would have its own commands, it needed a way to display which commands are available and their places on the jump table. That is the Self-Documenting feature. The trick was to get the resulting module to figure out for itself where it was in memory, and create the jump table in a nice, fairly safe place. I chose the cassette buffer, beginning at 832 for the table. To ascertain the module's location, the initialization code puts an RTS (96) at a Zero Page address, the does a JSR to that address. The processor stack holds the location from which the JSR jumped -- and can be found and massaged to find the beginning address of the module. From that, the jump table is created. [I] think it is clever. For the Self-Documenting feature, the writer of the modulette must use a particular protocol: BEGIN CLC BCC CODE BYTE"NAME,P,A,R,A,M,S",0 CODE The PRINT DOC routine finds the documentation (jump address + 3) and prints until the 0 is encountered. You can get a print-out with: OPEN4,4,7:CMD4:SYSaddr+3 PRINT#4:CLOSE4 All you really have to remember is to SYS the load address, then SYS addr+3 (to see the documentation -- not necessary in your program). All the commands are at 832+offset. You can get MARModule, with Maker and a full list of modulettes and protocol documentation at http://c64.eloadstar.com/ssocc/ DMM