4. JAM api description


Now we have to learn how to talk with loaded plugin. Here are the enums for different commands:

Jam commands
enum _JamMsg{
  JAM_INFO=1,
  JAM_INIT=2,
  JAM_ACTIVATE=3,
  JAM_SONGSELECT=4,
  JAM_SONGINFO=5,
  JAM_PLAY=6,
  JAM_STOP=7,
  JAM_DEACTIVATE=8,
  JAM_DEINIT=9,
  JAM_SONG_NEXT_HOOK=0xA,
  JAM_LOG_HOOK=0xB,
  JAM_ALERT_HOOK=0xC
} eJamMsg;


We send them with following function:

C function declaration (jam.h)
extern void *sendJamCmd(void *par0,void *par1,long msg,long val);
extern void *activePlugin;  /*pointer to our loaded plugin defined in m68k module below */


M68k implementation:

jam_m68k.s
XDEF _sendJamCmd
           XREF _activePlugin
           
_sendJamCmd:
          
          move.l        4(sp),a0  ;data pointer 
          move.l        8(sp),a1  ;data pointer 
          
          move.l        12(sp),d1  ;MSG
          move.l        16(sp),d0 ;parameter
          
          move.l        _activePlugin,a2        
          jsr           (a2)
          move.l        a0,d0    ;return value to d0
          
          rts
          
          BSS
    
_activePlugin:    ds.l  1



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