HP 3000 Manuals HP 3000 Manuals
Conversion of Data Types
The convert3 utility converts COMPUTATIONAL,
COMPUTATIONAL-3, COMPUTATIONAL-6 and DISPLAY data from RM/COBOL format to
the formats used by this system. The following sections describe how
these types of data are converted.
COMP/COMPUTATIONAL Data
The RM/COBOL system represents COMP (or COMPUTATIONAL) data in packed
decimal format with one character per byte stored in each least
significant four-bits. The most significant half-byte always contains
zero. If the picture string specifies a signed representation, an
additional byte is added to the least significant end of the string: a
negative value is represented by the hexadecimal value 0D, and a positive
value is represented by the hexadecimal value 0B.
Consider the following examples:
------------------------------------------------------------
| | | |
| Value | Picture Clause | RM Representation |
| | | (Hexadecimal) |
| | | |
------------------------------------------------------------
| | | |
| 1234 | PIC 9(5) COMP | 00 01 02 03 04 |
| | | |
| 1234 | PIC S9(5) COMP | 00 01 02 03 04 0B |
| | | |
| -1234 | PIC S9(5) COMP | 00 01 02 03 04 0D |
| | | |
------------------------------------------------------------
The conversion program produced by convert3 converts COMP data fields
into DISPLAY format, with sign trailing separate. This is compatible
with this COBOL system's treatment of RM/COBOL COMP fields in the source
program when the RM directive is set. See Chapter 3 for details. If
the data item is signed, the sign byte has the most significant half-byte
set to hexadecimal value 2.
After conversion, the examples above are represented as follows:
------------------------------------------------------------
| | | |
| Value | Picture Clause | This COBOL's |
| | | Representation |
| | | (Hexadecimal) |
| | | |
------------------------------------------------------------
| | | |
| 1234 | PIC 9(5) DISPLAY | 30 31 32 33 34 |
| | | |
| 1234 | PIC S9(5) DISPLAY | 30 31 32 33 34 2B |
| | | |
| -1234 | PIC S9(5) DISPLAY | 30 31 32 33 34 2D |
| | | |
------------------------------------------------------------
COMP-3/COMPUTATIONAL-3 Data
The RM/COBOL system represents COMP-3 data in packed decimal format with
the least significant half-byte holding the sign.
This sign half-byte contains the following values:
---------------------------------------------------------
| | |
| Field | RM Sign half-byte value (Hexadecimal) |
| | |
---------------------------------------------------------
| | |
| Unsigned | F |
| | |
| Signed, | B or F |
| Positive | |
| | |
| Signed, | D |
| Negative | |
| | |
---------------------------------------------------------
Consider the following examples:
------------------------------------------------------------
| | | |
| Value | Picture Clause | RM Representation |
| | | (Hexadecimal) |
| | | |
------------------------------------------------------------
| | | |
| 1234 | PIC 9(5) COMP-3 | 00 23 4F |
| | | |
| 1234 | PIC S9(5) COMP-3 | 00 23 4F |
| | | |
| -1234 | PIC S9(5) COMP-3 | 00 23 4D |
| | | |
------------------------------------------------------------
The only requirement for conversion is that the sign half-byte has to be
changed for signed positive fields to hexadecimal value C. After
conversion, the examples above are represented as follows:
------------------------------------------------------------
| | | |
| Value | Picture Clause | This COBOL's |
| | | Representation |
| | | (Hexadecimal) |
| | | |
------------------------------------------------------------
| | | |
| 1234 | PIC 9(5) COMP-3 | 00 23 4F |
| | | |
| 1234 | PIC S9(5) COMP-3 | 00 23 4C |
| | | |
| -1234 | PIC S9(5) COMP-3 | 00 23 4D |
| | | |
------------------------------------------------------------
COMP-6/COMPUTATIONAL-6 Data
The RM/COBOL system holds COMP-6 data in a similar format to COMP-3 data,
except there is no sign half-byte. If a sign is indicated in the picture
clause it is ignored and has no effect. The value held is always
positive.
Consider the following examples:
------------------------------------------------------------
| | | |
| Value | Picture Clause | RM Representation |
| | | (Hexadecimal) |
| | | |
------------------------------------------------------------
| | | |
| 1234 | PIC 9(5) COMP-6 | 00 12 34 |
| | | |
| 123456 | PIC S9(6) COMP-6 | 12 34 56 |
| | | |
------------------------------------------------------------
In order to maintain the size and capacity of the data items, this COBOL
system treats COMP-6 data items as this COBOL's COMP format fields, and
pads the field with binary zeros where necessary. After conversion, the
examples above are represented as follows:
------------------------------------------------------------
| | | |
| Value | Picture Clause | This COBOL's |
| | | Representation |
| | | (Hexadecimal) |
| | | |
------------------------------------------------------------
| | | |
| 1234 | PIC 9(5) COMP-6 | 00 04 D2 |
| | | |
| 123456 | PIC S9(6) COMP-6 | 01 E2 40 |
| | | |
------------------------------------------------------------
Note that the 9(5) COMP field is extended by one byte containing binary
zero in order to maintain the size of the original item. See
COMPUTATIONAL-6 (COMP-6) Data Types in Chapter 6 for details.
DISPLAY Data
You should be aware of the following differences between the
representation of numeric DISPLAY format data items, with sign INCLUDED,
under the RM/COBOL system and this COBOL system:
* This COBOL system does not encode a sign on the data if the data
is positive, whereas the RM/COBOL system increments the value of
the most significant half-byte by one to denote a positive value.
* This COBOL system increments the value of the most significant
half-byte by four to denote a negative value. The RM/COBOL system
increments the value of the byte by twenty-five (that is,
hexadecimal 19).
When the RM directive is set, a DISPLAY format data item with no sign
clause associated is treated by this system as though you had specified
the SIGN TRAILING IS SEPARATE clause. However, when the ANSI parameter
is set with the RM directive, a DISPLAY format data item with no
associated sign clause is treated as though you had specified the SIGN
TRAILING IS INCLUDED clause, which is the default state for such data
items in this COBOL system. The convert3 utility also allows you to
specify the type of sign used for DISPLAY format data items. See Chapter
9 for details on how you can do this.
Consider the following examples:
------------------------------------------------------------------
| | | |
| | | RM Representation |
| Value | Picture Clause | (Hexadecimal) |
| | | |
------------------------------------------------------------------
| | | | |
| | | Leading | Trailing |
| | | | |
| 123 | PIC 9(3) DISPLAY | 31 32 33 | 31 32 33 |
| | | | |
| 123 | PIC S9(3) DISPLAY | 41 32 33 | 31 32 43 |
| | | | |
| -123 | PIC S9(3) DISPLAY | 4A 32 33 | 31 32 4C |
| | | | |
------------------------------------------------------------------
After conversion, these examples are represented as follows:
------------------------------------------------------------------
| | | |
| | | This COBOL's |
| Value | Picture Clause | Representation |
| | | (Hexadecimal) |
| | | |
------------------------------------------------------------------
| | | | |
| | | Leading | Trailing |
| | | | |
| 123 | PIC 9(3) DISPLAY | 31 32 33 | 31 32 33 |
| | | | |
| 123 | PIC S9(3) DISPLAY | 31 32 33 | 31 32 33 |
| | | | |
| -123 | PIC S9(3) DISPLAY | 71 32 33 | 31 32 73 |
| | | | |
------------------------------------------------------------------