Convert BSC to Character (CVTBC)

Op Code (Hex)	Extender	Operand 1	Operand 2	Operand 3	Operand [4-6]
CVTBC 10AF		Receiver	Controls	Source

CVTBCB 1CAF	Branch options	Receiver	Controls	Source	Branch targets

CVTBCI 18AF	Indicator options	Receiver	Controls	Source	Indicator targets

Operand 1: Character variable scalar.

Operand 2: Character(3) variable scalar.

Operand 3: Character scalar.

Operand 4-6:

Branch Form-Branch point, instruction pointer, relative instruction number, or absolute instruction number.
Indicator Form-Numeric variable scalar or character variable scalar.

Bound program access

Built-in number for CVTBC is 130.
CVTBC (
       receiver          : address
       receiver_length   : unsigned binary(4)
       controls          : address
       source            : address
       source_length     : unsigned binary(4)
       return_code       : address of signed binary(4)
)

The return_code will be set as follows:

Return code	Meaning
`-1`	Completed Record.
`0`	Source Exhausted.
`1`	Truncated Record.

The receiver, controls and source parameters correspond to operands 1, 2 and 3 on the CVTBC operation.

The receiver_length and source_length parameters contain the length, in bytes, of the receiver and source strings. They are expected to contain values between 1 and 32,767.

The return_code parameter is used to provide support for the branch and indicator forms of the CVTBC operation. The user must specify code to process the return_code and perform the desired branching or indicator setting.

Description

This instruction converts a string value from the BSC (binary synchronous communications) compressed format to a character string. The operation converts the source (operand 3) from the BSC compressed format to character under control of the controls (operand 2) and places the result into the receiver (operand 1).

The source and receiver operands must both be character strings.

The controls operand must be a character scalar that specifies additional information to be used to control the conversion operation. It must be at least 3 bytes in length and have the following format:

Offset
Dec	Hex	Field Name		Data Type and Length
0	0	Controls operand		Char(3)
0	0		Source offset		Bin(2)
2	2		Record separator		Char(1)
3	3	--- End ---

The source offset specifies the offset where bytes are to be accessed from the source operand. If the source offset is equal to or greater than the length specified for the source operand (it identifies a byte beyond the end of the source operand), a template value invalid (hex 3801) exception is signaled. As output from the instruction, the source offset is set to specify the offset that indicates how much of the source is processed when the instruction ends.

The record separator, if specified with a value other than hex 01, contains the value used to separate converted records in the source operand. A value of hex 01 specifies that record separators do not occur in the converted records in the source.

Only the first 3 bytes of the controls operand are used. Any excess bytes are ignored.

The operation begins by accessing the bytes of the source operand located at the offset specified in the source offset. This is assumed to be the start of a record. The bytes of the record in the source operand are converted into the receiver record according to the following algorithm.

The strings to be built in the receiver are contained in the source as blank compression entries and strings of consecutive nonblank characters.

The format of the blank compression entries occurring in the source are as follows:

Offset
Dec	Hex	Field Name		Data Type and Length
0	0	Blank compression entry		Char(2)
0	0		Interchange group separator		Char(1)
1	1		Count of compressed blanks		Char(1)
2	2	--- End ---

The interchange group separator has a fixed value of hex 1D.

The count of compressed blanks provides for describing up to 63 compressed blanks. The count of the number of blanks (up to 63) to be decompressed is formed by subtracting hex 40 from the value of the count field. The count field can vary from a value of hex 41 to hex 7F. If the count field contains a value outside of this range, a conversion (hex 0C01) exception is signaled.

Strings of blanks described by blank compression entries in the source are repeated in the receiver the number of times specified by the blank compression count.

Nonblank strings in the source are copied into the receiver intact with no alteration.

If the receiver record is filled with converted data without encountering the end of the source operand, the instruction ends with a resultant condition of completed record. This can occur in two ways. If a record separator was not specified, the instruction ends when enough bytes have been converted from the source to fill the receiver. If a record separator was specified, the instruction ends when a source byte is encountered with that value prior to or just after filling the receiver record. The source offset value locates the byte following the last source record (including the record separator) for which conversion was completed. When the record separator value is encountered, any remaining bytes in the receiver are padded with blanks.

If the end of the source operand is encountered (whether or not in conjunction with a record separator or the filling of the receiver), the instruction ends with a resultant condition of source exhausted. The source offset value locates the byte following the last byte of the source operand. The remaining bytes in the receiver after the converted record are padded with blanks.

If the converted form of a record cannot be completely contained in the receiver, the instruction ends with a resultant condition of truncated record. The offset value for the source locates the byte following the last source byte for which conversion was performed, unless a blank compression entry was being processed. In this case, the source offset is set to locate the byte after the blank compression entry. If the source does not contain record separators, this condition can only occur for the case in which a blank compression entry was being converted when the receiver record became full.

Any form of overlap between the operands on this instruction yields unpredictable results in the receiver operand.

Resultant Conditions

Completed record-The receiver record has been completely filled with converted data from a source record.
Source exhausted-All of the bytes in the source operand have been converted into the receiver operand.
Truncated record-The receiver record cannot contain all of the converted data from the source record.

Authorization Required

None

Lock Enforcement

None

Exceptions

06 Addressing

0601 Space Addressing Violation
0602 Boundary Alignment
0603 Range

08 Argument/Parameter

0801 Parameter Reference Violation

0C Computation

0C01 Conversion

10 Damage Encountered

1004 System Object Damage State
1044 Partial System Object Damage

1C Machine-Dependent

1C03 Machine Storage Limit Exceeded

20 Machine Support

2002 Machine Check
2003 Function Check

22 Object Access

2201 Object Not Found
2202 Object Destroyed
2203 Object Suspended
2208 Object Compressed
220B Object Not Available

24 Pointer Specification

2401 Pointer Does Not Exist
2402 Pointer Type Invalid

2C Program Execution

2C04 Branch Target Invalid

2E Resource Control Limit

2E01 User Profile Storage Limit Exceeded

32 Scalar Specification

3201 Scalar Type Invalid

36 Space Management

3601 Space Extension/Truncation

38 Template Specification

3801 Template Value Invalid

44 Protection Violation

4401 Object Domain or Hardware Storage Protection Violation
4402 Literal Values Cannot Be Changed