[Not a bug] PLY_CFG_UseTranspositions + looping bug?

[tulinmola]

Hi there! First of all, thank you very very much for this software. It’s amazing!

I’ve been playing with exporting songs. My target is SDCC compiler. Following the guides, I ended compiling AKG player with this configuration:

compile_akg.asm
`
;What hardware? Uncomment the right one.
PLY_AKG_HARDWARE_CPC = 1
;PLY_AKG_HARDWARE_MSX = 1
;PLY_AKG_HARDWARE_SPECTRUM = 1
;PLY_AKG_HARDWARE_PENTAGON = 1

; Comment/delete this line if not using sound effects.
PLY_AKG_MANAGE_SOUND_EFFECTS = 1

; Configuration
PLY_CFG_ConfigurationIsPresent = 1
PLY_CFG_UseSpeedTracks = 1
; PLY_CFG_UseTranspositions = 1
PLY_CFG_UseEventTracks = 1
PLY_CFG_UseEffects = 1
PLY_CFG_UseInstrumentLoopTo = 1
PLY_CFG_NoSoftNoHard = 1
PLY_CFG_SoftOnly = 1
PLY_CFG_SoftOnly_ForcedSoftwarePeriod = 1
PLY_CFG_SoftOnly_SoftwareArpeggio = 1
PLY_CFG_SoftOnly_SoftwarePitch = 1
PLY_CFG_UseEffect_PitchDown = 1
PLY_CFG_UseEffect_SetVolume = 1

include “PlayerAkg.asm”
`

The configuration there is a merge of all my song configurations. To adapt the player to work with all of them.

Then, I use the usual rasm/Disark commands to generate SDCC compatible file:

`
$ rasm compile_akg.asm -o tmp/akg -s -sl -sq
$ Disark tmp/akg.bin src/akg.s –symbolFile tmp/akg.sym –sourceProfile sdcc
`

I convert my songs to binary with something like:

`
$ SongToAkg song.aks song.akg -bin -adr 0x8000 -smd –exportPlayerConfig
`

And play it with:

`
#include <cpctelera.h>

extern void PLY_AKG_INIT(void* songdata, u8 subSong) __z88dk_callee;
extern void PLY_AKG_PLAY();
extern const u8* song_akg;

void main(void) {
cpct_disableFirmware();

PLY_AKG_INIT(&song_akg, 0);

while (1) {
// play
PLY_AKG_PLAY();

// wait until next frame
cpct_waitHalts(2);
cpct_waitVSYNC();
}
}
`

Notes:
– cpct_disableFirmware just overwrites interrupt handler address with EI, RET
– cpct_waitHalts waits for halts
– cpct_waitVSYNC… wel… waits for vsync

So it simply calls AKG_PLAY 50 times per second and there is no other code that could cause side effects. And, in fact, it works great!

The issue comes when uncommenting PLY_CFG_UseTranspositions = 1 line in player compilation configuration (and recompiling everything). Then, the first time it plays the song everything goes OK. But, when looping, the second time –after a couple of frames– music slows down a lot. But the code still executes 50 times per second.

I’m not sure if it is a bug or I am doing something wrong. My inclination is towards the latter. But, what do you think?

And, of course, some of my songs uses transpositions… So keeping it uncommented is not a workaround, hehe.

It happens with all the songs I tested. So if you need the songs, the generated code, the project, or whatever else, just tell me and I will be happy to prepare it!

Thanks in advance!

Cheers,
Tulo

[Targhan]

Hi,

Just to be sure, before I delve any further, if you uncomment the Transpose flag, are you sure that:
– No transposition is actually present in the song, else some unexpected data will be present!
– You fully recompile your player.

If this is OK, I’ll whether it’s a bug or not :).

[Targhan]

Ok, re-reading the post better, I can see that you recompile the player BUT the songs have transpositions! This is a problem, because the player will not TRY to read the transposition bytes, and thus, will not skip them. So this WILL bug.

[tulinmola]

Hello. Such a quick response!

I have songs with and without transpositions. The slow down after the fist play loop happens when playing both type of songs.

When having the player compiled without transpositions and playing a song with them, it plays. And it looks like it simply does not apply the transpositions. Maybe it’s bugging more things internally. But I couldn’t notice. As you can see, the test environment is as small as possible.

[tulinmola]

As expected, the issue was on my side. Even having so few lines of code… It was a problem with calling the play function without saving all needed registers and ensuring interrupts couldn’t occur while playing. And it is clearly described in the documentation!

void main(void) {
  cpct_disableFirmware();

  // Init song
  __asm
    ld hl, #_songs_akg
    ld a, #0
    call _PLY_AKG_INIT
  __endasm;

  ; loop forever
  while (1) {
    // do play
    __asm
        di
        ex af,af'
        exx
          ; Only a few registers needs to be saved as the system requires them.
          push af
          push bc
          push ix
          push iy
            call _PLY_AKG_PLAY;
          pop iy
          pop ix
          pop bc
          pop af
        ex af,af'
        exx
        ei
    __endasm;

    // wait until next frame
    cpct_waitHalts(2);
    cpct_waitVSYNC();
  }
}

At least I hope this post serves as a complementary guide for running on SDCC.

Sorry for being such a mess. Thank you very much Julien!
Tulo

[Targhan]

Glad it’s working now :). I’ll add one item in the FAQ about the auxiliary registers, just in case.

[tulinmola]

Yes, I think it’ll be very valuable knowing which exact functions use alternate registers.

Thanks a lot!
Tulo

[Author]

Posts