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Subject: Re: [ub] [c++std-ext-14592] Re: Re: Sized integer types and char bits
From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2013-10-26 15:31:44


El 25/10/2013 1:38, Richard Smith escribió:
> On Thu, Oct 24, 2013 at 4:23 PM, <keld_at_[hidden]
> <mailto:keld_at_[hidden]>> wrote:
>
> I used to program some of these beast a while ago.
> There were C compilers and some UNIX port for them.
>
>
> Did their C compilers expose non-twos-complement integers, or did they
> emulate twos-complement?

In case you missed my previous message:

"According to ClearPath C compiler's manual:

http://public.support.unisys.com/2200/docs/cp14.0/pdf/78310422-011.pdf

//////////////////////////////////
//////////////////////////////////

Integer Type Conversions

UCS C represents an integer in 36-bit ones complement form (or 72-bit
ones complement form, if the long long type attribute is specified).
Unless the CONFORMANCE/ TWOSARITH keyword is used, there is no
representation change when converting a signed int value to unsigned int
or when converting an unsigned int value to signed int. For more
information on the CONFORMANCE keyword, see the C Compiler Programming
Reference Manual Volume 2.

Now if you read the Java documentation:

"Virtual Machine for the Java™ Platform on ClearPath OS 2200 JProcessor
[http://public.support.unisys.com/2200/docs/cp14.0/pdf/78310430-016.pdf]

//////////////////////////////////
//////////////////////////////////

8.5. JNI Transition Data Conversions

The Java language explicitly defines its numerical data types to very
specific formats and sizes:

- 8-bit 2’s complement signed byte
- 16-bit 2’s complement signed short
- 32-bit 2’s complement signed integer
- 64-bit 2’s complement signed long

Unfortunately, the Java data type definitions do not match or blend very
well with the UCS C data types:

- 9-bit 1’s complement signed char
- 18-bit 1’s complement short
- 36-bit 1’s complement integer and long
- 72-bit 1’s complement long long (signed only)

[...] When Java code calls native C code, the parameters are converted
from Java format to OS 2200 native format. When native C code calls Java
methods, the JProcessor JVM converts the parameters from native format
to Java format. The JProcessor JVM also performs the appropriate
conversions when the native C code calls JNI functions to get or set
object data items or arrays."

Best,

Ion


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