Kaffe Data Structure

jmutex: systems/unix-jthreads/jthread.h

 A mutex is represented by a two-word structure (_jthread), holder and waiting

jcondvar: systems/unix-jthreads/jthread.h

A condition variable is simply expressed as a list of threads waiting to be notified

callMethodInfo: support.h

The structure describes the information necessary to invoke a native or just-in-time compiled method.
 
  • It is the task of the sysdepCallMethod macro, usually defined in config/$arch/common.h, to generate a procedure call that conforms to the calling convention of a particular architecture or set of build tools.
  • The sysdepCallMethod macro takes a single argument of type callMethodInfo that describes where the parameters are, where the return value should go and what the signature of the method is.
  • `jvalue' is a union defined in include/jtypes.h.  It corresponds to an entry on the Java stack.
  • The suffixes i,j,b,c,s,l,f,d access the corresponding element of (Java) type int, long, boolean, char, short, ref, float, and double.
  • `args' is an array containing the arguments passed to the function. It corresponds to the Java stack and has `nrargs' valid entries with  the following property:
    1. If two adjacent slots on the Java stack are combined to a 64bit value, it will also use two array entries, and not one.  However, the first entry will contain the 64bit value (in j or d, depending on the type), and the second entry will be undefined.  This allows for easier access, while preserving indexing.  Thus, some array entries will have 0, some 32 and some 64 bits of valid data in them.  The callsize array says which one it is.
  • callsize[i] may be 0, 1, or 2, depending on the number of valid bits in args[i].  Similarly, calltype[i] contains the signature type of theargument in args[i] ('J', 'F', etc.).
  • Porters note that "callsize[i] == 2 iff callsize[i+1] == 0" -- this property is exploited by some sysdepCallMethod macros (sparc). `function' is a pointer to the method to be invoked.
  • `retsize' and `rettype' have the same value ranges as callsize[i] and calltype[i],  except they correspond to the return value.  The sysdepCallMethod must store the return value in the proper type at *ret.

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