Decrement Time (DECT)


Op Code (Hex) Operand 1 Operand 2 Operand 3 Operand 4
0444 Result time Source time Duration Instruction template
Operand 1: Character variable scalar.

Operand 2: Character scalar.

Operand 3: Packed decimal scalar.

Operand 4: Space pointer.

Bound program access
Built-in number for DECT is 98.
DECT (
      result_time            : address
      source_time            : address
      duration               : address of packed decimal
      instruction_template   : address
)

Description

The time specified by operand 2 is decremented by the time duration specified by operand 3. The resulting time is placed in operand 1. Operand 4 defines the data definitional attributes for operands 1 through 3.

The following describes the instruction template.

Offset
Dec Hex
Field Name
Data Type and Length
0 0
Instruction template
Char(*)
0 0
Instruction template size
Bin(4)
4 4
Operand 1 data definitional attribute template number
UBin(2)
6 6
Operand 2 data definitional attribute template number
UBin(2)
8 8
Operand 3 data definitional attribute template number
UBin(2)
10 A
Operand 1 length
UBin(2)
12 C
Operand 2 length
UBin(2)
14 E
Operand 3 length
UBin(2)
14 E
Fractional number of digits
Char(1)
15 F
Total number of digits
Char(1)
16 10
Input indicators
Char(2)
16 10
Reserved (binary 0)
Bit 0
16 10
Tolerate data decimal errors
Bit 1



0 = No toleration
1 = Tolerate



16 10
Reserved (binary 0)
Bits 2-15
18 12
Reserved (binary 0)
Char(24)
42 2A
Data definitional attribute template list
Char(*)
42 2A
Size of the DDAT list
UBin(4)
46 2E
Number of DDATs
UBin(2)
48 30
Reserved (binary 0)
Char(10)
58 3A
DDAT offset
[*] UBin(4)
* *
Data definitional attribute template
[*] Char(*)
* *
--- End ---

A data definitional attribute template (DDAT) number is a number that corresponds to the relative position of a template in the data definitional attribute template list. For example, the number 1 references the first template. The valid values for this field are 1, 2, and 3.

The DDATs for operands 1 and 2 must be valid for a time and must be identical. The DDAT for operand 3 must be valid for a time duration. Otherwise, a template value invalid  (hex 3801) exception will be issued.

Operand 1 length, operand 2 length, and operand 3 length are specified in number of bytes.

The input indicator, tolerate data decimal errors, is used to determine whether errors found in the packed data for the duration will generate exceptions or will be ignored. When the errors are to be tolerated, the following rules will apply:

  1. An invalid sign nibble found in the packed data value will be changed to a hex F.

  2. Any invalid decimal digits found in the packed data value will be forced to zero.

  3. If all digits of a packed data value become zero, and no decimal overflow condition exists, the sign will be set to hex F. If all digits are zero and a decimal overflow condition exists, then the sign will not be changed, but its representation will be changed to the preferred sign code.

The size of the DDAT list is specified in bytes.

The number of DDATs is the count of DDATs specified for this instruction template. The maximum number of DDATs that can be specified is 3.

The DDAT offset is the number of bytes from the start of the DDAT list to the start of the specific DDAT. There should be as many DDAT offsets as there are DDATs specified.

A data definitional attribute template defines the presentation of the data. Each template describes the definitional attributes of the operands. The length of the time and time duration character operands will be defined by the templates. For a further description of the data definitional attribute template, see Data Definitional Attribute Template.

Authorization Required

Lock Enforcement

Exceptions

06 Addressing

08 Argument/Parameter

0C Computation

10 Damage Encountered

20 Machine Support

22 Object Access

24 Pointer Specification

2E Resource Control Limit

32 Scalar Specification

36 Space Management

38 Template Specification

44 Protection Violation