Re: Classpath build process and VM-specific issues

[Steven Augart]

Etienne Gagnon wrote:
> Can JNI actually be implemented on a 16-bit per byte system?
> Anybody has a reasonable answer?

Such a system, to implement JNI, will have to have a compiler-defined 
extension for a signed 8-bit byte type, a bit like the GNU "long long" 
extension.  ANSI C allows a compiler to add additional types, as long 
as it implements the standard ones.

It will also need an unsigned 8 bit quantity (jboolean), signed and 
unsigned 16 bit ones (jshort, jchar), signed 32 and 64 bit quantities 
(jint, jlong), and (the stinger) 32 bit and 64 bit floating point 
values (jfloat, jdouble).

Now, I'm not sure how many people who use JNI are going to actually 
depend upon a jfloat being exactly 32 bits long (and not one bit 
more!) or a jdouble being exactly 64 bits long, but according to table 
3-1 in the JNI spec they are indeed entitled to make that assumption. 
 So, any C compiler that you want to write JNI code with had better 
have a way to specify floating point types with those lengths.


--
Steven Augart

Jikes RVM, a free, open source, Virtual Machine:
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