Communicator e3000 MPE/iX Release 6.5 (Non-Platform Software Release C.65.00 (30216-90291)

82 Chapter3

Growth Solution

C/iX Supports 64-bit Integers

by Walter Murray

Support Technology Lab

In response to a number of customer requests, we have enhanced the C/iX compiler, the

C/iX Library, and the MPE/iX Millicode library to provide full support for a 64-bit integer

data type. This article provides the information you need in order to declare, operate on,

and perform input/output operations on 64-bit integers in C.

All of the changes have been made in such a way as to ensure forward compatibility to

MPE/iX 6.5 from pre-6.5 systems. All existing C/iX applications should work the same on

6.5 as they did on earlier systems, whether you recompile and relink on 6.5, or whether

you bring your executable programs and libraries forward to 6.5 without recompilation.

However, there are some backward compatibility issues to be aware of if you compile C

code on MPE/iX 6.5 and want to move it to a pre-6.5 system. Please see the article

“Compatibility Considerations for COBOL and C", elsewhere in this Communicator.

The 64-bit integral type is referred to in C/iX as "long long". The long long data type is an

extension to ANSI C. If you compile with the CCXL command and want to use 64-bit

integers in ANSI mode, you must enable ANSI extensions by using the compiler option

"+e" or "–Ae". If you compile with the c89 command, enable ANSI extensions by specifying

"–Wc,+e".

To declare a signed 64-bit integer, use the type speciﬁer "signed long long int", where

"signed" and "int" are optional. To declare an unsigned 64-bit integer, use the type speciﬁer

"unsigned long long int", where "int" is optional. Note that, for compatibility reasons, the

type "long int" remains 32 bits, the same as type "int".

A 64-bit integer is stored in 8 bytes, 8-byte aligned, with higher-order bits stored in

lower-addressed bytes. (The high-order 32 bits are stored in the "left" word.)

A signed long long int can represent integers in the range -9223372036854775808 to

9223372036854775807. An unsigned long long int can represent integers in the range 0 to

18446744073709551615.

To write a signed long long integer constant, whether decimal, octal, or hexadecimal, you

must use a sufﬁx of "LL". Likewise, an unsigned long long integer constant must be

written with a sufﬁx of "ULL". (Sufﬁxes may be written in upper, lower, or mixed case.)

Within your C code you may use variables of type long long the same as you would use

variables of any other integral type. For example, a variable of type long long can be used

as an operand in an arithmetic or relational expression, as a function argument,

parameter, or return, as a subscript, etc. You can declare arrays, structure members, and

bit-ﬁelds of type long long. You can take the address of a long long, use a cast between long

long and other types, and initialize a long long at the point where it is declared.

For converting to and from 64-bit integers, the scanf() and printf() families of functions

have been enhanced to permit "ll" (ell ell) as a modiﬁer to a conversion speciﬁer of "d", "i",

"o", "u", "x", or "X". There are also two new functions, strtoll() and strtoull(), which are the

64-bit equivalents of strtol() and strtoul().