iX Computer Systems - Edition 1 (32715-90001)

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overhead associated with them becomes noticeable. The Replace GOSUBs

screen can, with certain restrictions, be used to replace a GOSUB with

the body of the referenced subroutine. This is possible when there are

enough available line numbers after the GOSUB to insert the entire

subroutine before the next line, and the subroutine does not contain and

GOTO statements or any lines that are targets of branches.

The Replace GOSUBs screen prompts you for a line range to use to search

for eligible GOSUBs. It also asks for the maximum number of lines to be

inserted for each GOSUB. The Program Analyst then creates an ASCII file

containing a copy of the referenced subroutine. If you choose to replace

the GOSUB with the subroutine, the GOSUB statement is deleted and the

copy of the subroutine is inserted in its place. If the subroutine

contains consecutive assignment statements, the Program Analyst combines

them into fewer lines if possible.

The existence of this screen should not suggest that all GOSUBs should be

eliminated. Only those that are used very frequently should be

considered for replacement.

The Replace GOSUBs screen is useful in conjunction with the Extract

Subunit screen described later. Replace GOSUBs can help to resolve

subroutine references that might otherwise prevent a successful

extraction.

The Optimize PACKFMTs Screen. The purpose of this screen is to generate

SKIP clauses for PACKFMT statement to minimize packing and unpacking of

variables.

Often a subunit needs to access only a few items specified in a PACKFMT

statement. In a PACK or UNPACK statement, the entire record will be

transferred between the string buffer and the variable, even if the

PACKFMT statement has information for many more items than the subunit

is using.

To improve efficiency, the PACKFMT specification can contain one or more

SKIP clauses. A SKIP specifies that a certain number of bytes in the

string buffer are to be ignored during an UNPACK and skipped over during

a PACK.

The Optimize PACKFMTs screen determines which items can be skipped,

calculates the number of bytes to skip, and then modifies a PACKFMT

accordingly.

When you enter this screen, you are prompted for the line number of a

PACKFMT statement. You can enter a line number or use a softkey to list

the line numbers of all of the PACKFMT statements in your program. If

the correct line number of a PACKFMT is entered, each item in the PACKFMT

statement is examined. If the PACKFMT statement is used anywhere else in

the subunit, or if it is in common or is a parameter to the subunit, the

Program Analyst assumes that it is needed and cannot be skipped.

Otherwise, the Program Analyst determines the number of bytes in that